Buprenorphine (buprenorphine)

Dosage of buprenorphine and buprenorphine hydrochloride usually is expressed in terms of buprenorphine. Dosage of buprenorphine hydrochloride subdermal implants may be expressed as either the salt or the base.

Not all formulations, strengths, or dose combinations of oral transmucosal buprenorphine/naloxone preparations are bioequivalent.

Patients who currently are receiving generic buprenorphine or buprenorphine/naloxone sublingual tablets (i.e., generic equivalents of Subutex(R) or Suboxone(R) sublingual tablets) and are switching to buprenorphine/naloxone sublingually dissolving strips (Suboxone(R)), or vice versa, should continue to receive the same drug dosage. However, not all strengths and dose combinations of the strips and sublingual tablets are bioequivalent. Because of potentially greater bioavailability with the strips relative to the tablets, patients should be monitored for underdosage (e.g., manifestations of withdrawal) or overdosage when switching between sublingual dosage forms and the dosage should be adjusted when indicated.

The 4 strengths of Suboxone(R) sublingually dissolving strips differ in size and buprenorphine and naloxone concentrations (on a % (w/w) basis). Switching between various combinations of lower- and higher-strength strips to obtain the same total dose may result in changes in systemic exposure to buprenorphine and naloxone and require that the patient be monitored for underdosage or overdosage. Therefore, substitution of one or more strip strengths for another without the prescriber's approval is not recommended. Because systemic exposure to naloxone is somewhat higher after buccal compared with sublingual administration of the strips, sublingual administration is recommended during induction to minimize the risk of precipitated withdrawal. However, exposure to buprenorphine is similar following either buccal or sublingual administration, and once induction is complete, patients can switch between buccal and sublingual administration without substantial risk of underdosage or overdosage.

Bunavail(R) and Zubsolv(R) have different bioavailabilities than Suboxone(R) (or generic equivalent) sublingual tablets. Patients switching between these preparations should receive a different dosage strength (see Table 1 and Table 2) and should be monitored for underdosage or overdosage. Dosage adjustments may be necessary. Systemic buprenorphine exposure following administration of one Suboxone(R) sublingual tablet containing buprenorphine 8 mg and naloxone 2 mg is equivalent to that achieved following administration of one Bunavail(R) buccally dissolving strip containing buprenorphine 4.2 mg and naloxone 0.7 mg or one Zubsolv(R) sublingual tablet containing buprenorphine 5.7 mg and naloxone 1.4 mg.

Table 1. Corresponding Doses and Strengths of Suboxone(R) Sublingual Tablets and Bunavail(R) Buccally Dissolving Strips

Suboxone(R) Sublingual Dose or Corresponding Bunavail(R) Strip Tablet Strength Strength Buprenorphine 4 mg and naloxone 1 mg Buprenorphine 2.1 mg and naloxone 0.3 mg Buprenorphine 8 mg and naloxone 2 mg Buprenorphine 4.2 mg and naloxone 0.7 mg Buprenorphine 12 mg and naloxone 3 Buprenorphine 6.3 mg and naloxone 1 mg mg

Table 2. Corresponding Dosage Strengths of Suboxone(R) Sublingual Tablets (or Generic Equivalent) and Zubsolv(R) Sublingual Tablets

Suboxone(R) (or Generic Equivalent) Corresponding Zubsolv(R) Sublingual Sublingual Dose (Tablet Strength) Tablet Strength Buprenorphine 2 mg and naloxone 0.5 One 1.4-mg/0.36-mg tablet mg (as one 2-mg/0.5-mg tablet) Buprenorphine 4 mg and naloxone 1 mg One 2.9-mg/0.71-mg tablet (as two 2-mg/0.5-mg tablets) Buprenorphine 8 mg and naloxone 2 mg One 5.7-mg/1.4-mg tablet (as one 8-mg/2-mg tablet) Buprenorphine 12 mg and naloxone 3 One 8.6-mg/2.1-mg tablet mg (as one 8-mg/2-mg tablet and two 2-mg/0.5-mg tablets) Buprenorphine 16 mg and naloxone 4 One 11.4-mg/2.9-mg tablet mg (as two 8-mg/2-mg tablets)

Transdermal buprenorphine has not been studied in patients with severe hepatic impairment; use of an alternative analgesic regimen that allows for greater dosage flexibility should be considered in these patients.

When buprenorphine buccally dissolving strips (Belbuca(R)) are used for analgesia in patients with severe hepatic impairment (i.e., Child-Pugh class C), the usual initial dosage should be reduced and each incremental change in dosage during titration should be reduced by one-half (i.e., from 150 mcg to 75 mcg). No dosage adjustment is required in patients with moderate hepatic impairment, but patients with either moderate or severe hepatic impairment should be monitored for overdosage and toxicity.

When buprenorphine or buprenorphine/naloxone is used sublingually or buccally for the management of opiate dependence in patients with mild hepatic impairment, plasma concentrations and half-lives of the drugs are not substantially altered. However, in individuals with moderate or severe hepatic impairment, plasma concentrations of both buprenorphine and naloxone are increased and half-lives of the drugs are prolonged. Naloxone is affected to a greater degree than buprenorphine, and the magnitude of the difference in effect is greater in individuals with severe hepatic impairment than in those with moderate hepatic impairment. (See Pharmacokinetics: Elimination.) This may result in an increased risk of precipitated withdrawal during induction and interference with buprenorphine's efficacy throughout treatment. Buprenorphine/naloxone should be avoided in patients with severe hepatic impairment and may not be appropriate for those with moderate hepatic impairment. In patients with moderate hepatic impairment, buprenorphine/naloxone is not recommended for induction therapy but may be used with caution and careful monitoring for maintenance treatment following induction therapy with buprenorphine alone. The manufacturer states that the initial dose and titration increments of buprenorphine administered as the single-entity sublingual tablets should be reduced by one-half in patients with severe hepatic impairment and recommends that patients with either moderate or severe hepatic impairment be monitored for buprenorphine overdosage or toxicity.

Use of buprenorphine extended-release subcutaneous injection or buprenorphine subdermal implants is not recommended in patients with preexisting moderate to severe hepatic impairment since the extended-release injection does not allow for rapid adjustment of plasma buprenorphine concentrations and the implant dosage cannot be titrated.

When generic buprenorphine sublingual tablets (i.e., generic equivalents of Subutex(R) sublingual tablets), generic buprenorphine/naloxone sublingual tablets (i.e., generic equivalents of Suboxone(R) sublingual tablets), or buprenorphine/naloxone sublingually dissolving strips (Suboxone(R)) are used for induction therapy, the recommended induction dosage of buprenorphine on day 1 is up to 8 mg (alone or in fixed combination with up to 2 mg of naloxone). Induction should be initiated on day 1 with a buprenorphine dose of 2 or 4 mg (alone or in fixed combination with naloxone 0.5 or 1 mg, respectively), with additional doses of 2 or 4 mg administered at approximately 2-hour intervals if there are continued withdrawal symptoms and sedation is not observed. Use of an opiate withdrawal scale (e.g., COWS) during induction can be helpful in assessing the effects of administered doses. On day 2, a single dose of up to 16 mg of buprenorphine (alone or in fixed combination with up to 4 mg of naloxone) is given. Other induction dosages that also employ a low initial dose with rapid titration to an effective maintenance dosage have been used.

For oral transmucosal maintenance treatment, buprenorphine/naloxone is preferred over buprenorphine alone. (See initial paragraphs of Opiate Dependence under Dosage and Administration: Dosage.) From day 3 onward, buprenorphine/naloxone dosage should be adjusted in increments or decrements of 2 or 4 mg of buprenorphine in fixed combination with 0.5 or 1 mg, respectively, of naloxone daily to a dosage that suppresses opiate withdrawal symptoms and ensures that the patient continues buprenorphine treatment. The maintenance buprenorphine/naloxone dosage generally ranges from 4-24 mg of buprenorphine in fixed combination with 1-6 mg of naloxone daily. The recommended buprenorphine/naloxone target dosage during maintenance treatment is 16 mg of buprenorphine and 4 mg of naloxone as a single daily dose. Dosages exceeding 24 mg of buprenorphine in fixed combination with 6 mg of naloxone daily have not been shown to provide any additional clinical advantage.

No dosing information is available for this tab.

Drug interactions that reportedly occur with other opiate agonists may also potentially occur during administration of buprenorphine.

Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

Opioid Analgesics/Opioid Antagonists

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Naltrexone, nalmefene, and samidorphan are opioid antagonists and thus inhibit the effects of opioid analgesics.(1-3)

CLINICAL EFFECTS: Concurrent administration or the administration of naltrexone within 7-10 days of opioids may induce acute abstinence syndrome or exacerbate a pre-existing subclinical abstinence syndrome.(1,4) Patients taking naltrexone may not experience beneficial effects of opioid-containing medications.(4) Samidorphan can precipitate opioid withdrawal in patients who are dependent on opioids. In patients who use opioids, delay initiation of samidorphan for a minimum of 7 days after last use of short-acting opioids and 14 days after last use of long-acting opioids.(3) Concurrent use of nalmefene tablets with opioid agonists may prevent the beneficial effects of the opioid.(2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of naltrexone states that the administration of naltrexone concurrently with opioids or to patients dependent on opioids is contraindicated.(1,4) Patients previously dependent on short-acting opioids should be opioid-free for a minimum of seven to ten days before beginning naltrexone therapy. Patients previously on buprenorphine or methadone may be vulnerable to withdrawal symptoms for as long as 2 weeks.(1,4) The manufacturer of naltrexone states that the naloxone challenge test, described in the naltrexone prescribing information, can be administered to determine if patients are opioid free.(1) The manufacturer of samidorphan states the concurrent use of samidorphan in patients using opioids or undergoing acute opioid withdrawal is contraindicated. Prior to initiating samidorphan, there should be at least a 7-day opioid free interval from the last use of short-acting opioids, and at least a 14-day opioid free interval from the last use of long-acting opioids.(3) The UK manufacturer of nalmefene tablets (for reduction of alcohol consumption) states the concurrent use of opioid analgesics is contraindicated.(2) Suspend the use of nalmefene tablets for 7 days prior to the anticipated use of opioids (e.g., elective surgery).(2)

DISCUSSION: A double-blind, randomized, placebo-control study evaluated pain relief and side effects of 35 opioid-naive patients undergoing cesarean section. All patients received spinal anesthesia (bupivacaine and morphine) and were randomized to also receive placebo, naltrexone 3 mg, or naltrexone 6 mg. Patients treated with naltrexone experienced shorter duration of pain relief (not statistically significant), however incidence of opioid-induced side effects was reduced. Patients in the naltrexone 6 mg group had lower rates of pruritus, vomiting, and somnolence (all statistically significant) compared to the placebo group.(5) In a double-blind, randomized, placebo-control trial ten recreational opioid users were studied to determine the effects of hydromorphone (4 mg and 16 mg), tramadol (87.5 mg, 175 mg, and 350 mg), and placebo after pretreatment with naltrexone (50 mg) or placebo. Results show that lower doses of hydromorphone and tramadol acted similar to placebo. Hydromorphone 16 mg alone caused euphoria and miosis which were blocked by naltrexone. Tramadol 350 mg produced a lower magnitude of euphoria and miosis compared to hydromorphone. Naltrexone partially diminished the euphoria caused by tramadol, while it enhanced some of the unpleasant monoaminergic effects (flushing, malaise, vomiting).(6) A case report describes a 28 year-old ex-heroin addict who was stable on methadone 100 mg daily and simultaneously stopped using heroin and began drinking alcohol. He was admitted to the hospital for alcohol detoxification and, by mistake, was given naltrexone 100 mg instead of methadone 100 mg. The patient experienced withdrawal symptoms including chills, agitation, muscle and abdominal pain, generalized piloerection, and dilated pupils. Treatment of withdrawal was titrated to treat symptoms and required administration 78 mg of parenteral hydromorphone, after which the patient experienced relief for the following six hours.(8) Intentional administration of an opioid antagonist, naloxone, with opioid analgesics has been performed with close monitoring to lower required opioid dose by inducing withdrawal. Three case reports describe patients who had improved pain relief on significantly reduced doses of opioid analgesics.(8) In a double-blind controlled trial, 267 trauma patients were randomized to receive 0.05 mg/kg intravenous morphine either alone or in combination with 5 mg naltrexone oral suspension. Evaluated endpoints include reduction of pain and incidence of side effects. Results indicate that ultra-low dose naltrexone does not alter opioid requirements for pain control, but does lower incidence of nausea [2 (1.16%) vs 16 (11.6%), p<0.001].(9)

Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

Agents That May Cause Respiratory Depression/Sodium Oxybate

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Oxybate by itself may be associated with severe somnolence or respiratory depression. Concurrent use with other CNS depressants may further increase the risk for respiratory depression or loss of consciousness.(1-3)

CLINICAL EFFECTS: Concurrent use of sodium oxybate and sedative hypnotics or alcohol may further increase the risk for profound sedation, respiratory depression, coma, and/or death.(1,2) Fatalities have been reported.(3)

PREDISPOSING FACTORS: Based upon FDA evaluation of deaths in patients taking sodium oxybate, risk factors may include: use of multiple drugs which depress the CNS, more rapid than recommended oxybate dose titration, exceeding the maximum recommended oxybate dose, and prescribing for unapproved uses such as fibromyalgia, insomnia or migraine. Note that in oxybate clinical trials for narcolepsy 78% - 85% of patients were also receiving concomitant CNS stimulants.(1-3)

PATIENT MANAGEMENT: Avoid use of concomitant opioids, benzodiazepines, sedating antidepressants, sedating antipsychotics, general anesthetics, or muscle relaxants, particularly when predisposing risk factors are present. If combination use is required, dose reduction or discontinuation of one or more CNS depressants should be considered. If short term use of an opioid or general anesthetic is required, consider interruption of sodium oxybate treatment.(1,2) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. The risk of opioid-related overdose or overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. Consider these risks when using concurrently with other agents that may cause CNS depression.(4) Discuss opioid reversal agents (e.g., naloxone, nalmefene) with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing an opioid reversal agent (e.g., naloxone, nalmefene) to patients prescribed medicines to treat OUD or opioid analgesics who are at increased risk of opioid overdose (such as those taking CNS depressants) and when a patient has household members/close contacts at risk for accidental overdose. Discuss the options for obtaining an opioid reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).(5)

DISCUSSION: The FDA evaluated sodium oxybate postmarket fatal adverse event reports from the FDA Adverse Event Reporting System(AERS)and from the manufacturer. Although report documentation was not always optimal or complete, useful information was obtained. Factors which may have contributed to fatal outcome: concomitant use of one or more drugs which depress the CNS, more rapid than recommended oxybate dose titration, exceeding the maximum recommended oxybate dose, and prescribing for unapproved uses such as fibromyalgia, insomnia or migraine. Many deaths occurred in patients with serious psychiatric disorders such as depression and substance abuse. Other concomitant diseases may have also contributed to respiratory and CNS depressant effects of oxybate.(3)

Anticholinergics; Opioids/Eluxadoline

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Eluxadoline is a mixed mu-opioid and kappa-opioid agonist and delta-opioid antagonist and may alter or slow down gastrointestinal transit.(1)

CLINICAL EFFECTS: Constipation related adverse events that sometimes required hospitalization have been reported, including the development of intestinal obstruction, intestinal perforation, and fecal impaction.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid use with other drugs that may cause constipation. If concurrent use is necessary, evaluate the patient's bowel function regularly. Monitor for symptoms of constipation and GI hypomotility, including having bowel movements less than three times weekly or less than usual, difficulty having a bowel movement or passing gas, nausea, vomiting, and abdominal pain or distention.(1) Instruct patients to stop eluxadoline and immediately contact their healthcare provider if they experience severe constipation. Loperamide may be used occasionally for acute management of severe diarrhea, but must be discontinued if constipation develops.(1)

DISCUSSION: In phase 3 clinical trials, constipation was the most commonly reported adverse reaction (8%). Approximately 50% of constipation events occurred within the first 2 weeks of treatment while the majority occurred within the first 3 months of therapy. Rates of severe constipation were less than 1% in patients receiving eluxadoline doses of 75 mg and 100 mg.(1)

Buprenorphine; Pentazocine/Chronic Opioids

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Buprenorphine antagonizes mu-opiate receptors.(1) Pentazocine is a mixed agonist-antagonist at opiate receptors.(2) Other opioids agonize mu-opiate receptors.

CLINICAL EFFECTS: Concurrent use of buprenorphine or pentazocine with other opioids in opioid dependent patients may result in withdrawal symptoms. Concurrent use in other patients may result in additive or decreased analgesia, decreased opioid side effects, and/or renarcotization.

PREDISPOSING FACTORS: Patients dependent on opioids or taking higher doses of opioids may be more likely to experience withdrawal symptoms with concurrent use.

PATIENT MANAGEMENT: Use buprenorphine and pentazocine with caution in patients maintained or dependent on other opioids and monitor for signs of withdrawal. In other patients, also monitor for changes in analgesic effects. The manufacturer of Sublocade states buprenorphine may precipitate opioid withdrawal in patients who are currently physically dependent on full opioid agonists. The risk of withdrawal may be increased if buprenorphine is given less than 6 hours after short-acting opioids (such as heroin, morphine) and less than 24 hours after long-acting opioids (such as methadone).(3)

DISCUSSION: In clinical trials, administration of buprenorphine injection produced withdrawal symptoms in patients maintained on methadone (30 mg daily) when administered 2 hours post-methadone,(4) but not when administered 20 hours post-methadone.(5) In another study, sublingual buprenorphine produced withdrawal symptoms in patients maintained on methadone. Symptoms were more pronounced in patients maintained on 60 mg daily doses than in patients maintained on 30 mg daily doses.(6) In a study of 10 patients maintained on methadone (100 mg daily), only three were able to tolerate escalating sublingual doses of buprenorphine/naloxone up to 32/8 mg. Split doses produced less withdrawal symptoms than full doses.(7) In a case report, a heroin-user maintained in a buprenorphine-maintenance program began stockpiling his buprenorphine instead of ingesting it and began using heroin. He then decided to re-initiate treatment on his own and ingested between 80 and 88 mg of buprenorphine over a two day period and experienced extreme withdrawal symptoms, despite restarting heroin during these symptoms. Methadone relieved his withdrawal symptoms.(8)

Moderate Interaction: Assess the risk to the patient and take action as needed.

Agents With Hyponatremia Risk/Desmopressin

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Carbamazepine, chlorpromazine, lamotrigine, NSAIDs, opioids, SSRIs, thiazide diuretics, and/or tricyclic antidepressants increase the risk of hyponatremia.(1-3)

CLINICAL EFFECTS: Concurrent use may increase the risk of hyponatremia with desmopressin.(1-3)

PREDISPOSING FACTORS: Predisposing factors for hyponatremia include: polydipsia, renal impairment (eGFR < 50 ml/min/1.73m2), illnesses that can cause fluid/electrolyte imbalances, age >=65, medications that cause water retention and/or increase the risk of hyponatremia (glucocorticoids, loop diuretics).

PATIENT MANAGEMENT: The concurrent use of agents with a risk of hyponatremia with desmopressin may increase the risk of hyponatremia. If concurrent use is deemed medically necessary, make sure serum sodium levels are normal before beginning therapy and consider using the desmopressin nasal 0.83 mcg dose. Consider measuring serum sodium levels more frequently than the recommended intervals of: within 7 days of concurrent therapy initiation, one month after concurrent therapy initiation and periodically during treatment. Counsel patients to report symptoms of hyponatremia, which may include: headache, nausea/vomiting, feeling restless, fatigue, drowsiness, dizziness, muscle cramps, changes in mental state (confusion, decreased awareness/alertness), seizures, coma, and trouble breathing. Counsel patients to limit the amount of fluids they drink in the evening and night-time and to stop taking desmopressin if they develop a stomach/intestinal virus with nausea/vomiting or any nose problems (blockage, stuffy/runny nose, drainage).(1)

DISCUSSION: In clinical trials of desmopressin for the treatment of nocturia, 4 of 5 patients who developed severe hyponatremia (serum sodium <= 125 mmol/L) were taking systemic or inhaled glucocorticoids. Three of these patients were also taking NSAIDs and one was receiving a thiazide diuretic.(2) Drugs associated with hyponatremia may increase the risk, including loop diuretics, carbamazepine, chlorpromazine, glucocorticoids, lamotrigine, NSAIDs, opioids, SSRIs, thiazide diuretics, and/or tricyclic antidepressants.(1,3-4)

Buprenorphine/Benzodiazepines

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Buprenorphine is a partial agonist at mu-opioid receptors leading to ceiling effects which limit agonist activity, including respiratory depression, at high doses. However, concomitant benzodiazepine use (e.g. taken shortly after buprenorphine dose) or high doses of benzodiazepines may lead to potentiation of respiratory depression, counteracting the ceiling effect.(1,2) Concurrent use of buprenorphine and benzodiazepines may result in additive CNS depression.(3)

CLINICAL EFFECTS: Concurrent use may result in profound sedation, respiratory depression, coma, and/or death. Fatal respiratory depression has occurred with the combination of buprenorphine and a benzodiazepine.(1-2,4-7) High benzodiazepine levels have been identified in 80% or more of buprenorphine fatalities.(6)

PREDISPOSING FACTORS: Patients with a history of alcohol or benzodiazepine abuse may be at risk for relapse and overuse or abuse of prescribed benzodiazepines.(1,2,4,6) Individuals with significant obstructive pulmonary disease (COPD), sleep apnea, the elderly, and debilitated patients are at greater risk for respiratory depression from either agent.(1,2,8)

PATIENT MANAGEMENT: Limit prescribing opioid analgesics with CNS depressants such as benzodiazepines to patients for whom alternatives are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management.(3) Medication assisted therapy (MAT) with buprenorphine is not contraindicated in patients taking CNS depressants; however discontinuation of CNS depressants is preferred in most cases. In some cases, monitoring at a higher level of care for tapering may be appropriate. In others gradual tapering or decreasing to the lowest effective dose of the CNS depressant is appropriate. For buprenorphine patients newly starting a benzodiazepine, consider beginning the benzodiazepine at a lower than usual dose, especially if predisposing factors (e.g. COPD, sleep apnea, debilitation, elderly) are present. High doses of benzodiazepines are associated with a greater risk for respiratory depression. Use the lowest effective dose and monitor for excessive sedation or respiratory depression, particularly in patients with predisposing risk factors for respiratory compromise.(1,2) Buprenorphine-naloxone combination products are used for maintenance treatment of opioid dependence. Patients with comorbid benzodiazepine dependence, on high doses of benzodiazepines, or a history of benzodiazepine abuse may require benzodiazepine detoxification prior to initiation of office-based buprenorphine treatment.(3) For patients receiving opioid maintenance treatment, it would be prudent to assure all controlled substance prescriptions are approved or written by the buprenorphine-naloxone provider.(5) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. The risk of opioid-related overdose or overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. Consider these risks when using concurrently with other agents that may cause CNS depression.(9) Monitor patients receiving concurrent therapy for unusual dizziness or lightheadedness, extreme sleepiness, slowed or difficult breathing, or unresponsiveness.(3) Discuss opioid reversal agents (e.g., naloxone or nalmefene) with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing opioid reversal agents (e.g., naloxone, nalmefene) to patients prescribed medicines to treat OUD or opioid analgesics who are at increased risk of opioid overdose (such as those taking CNS depressants) and when a patient has household members/close contacts at risk for accidental overdose. Discuss the options for obtaining an opioid reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).(10)

DISCUSSION: Buprenorphine is a partial agonist at mu-opioid receptors leading to ceiling effects which limits agonist activity, including respiratory depression, at high doses. However, concomitant benzodiazepine use (e.g. taking shortly after buprenorphine dose) or high doses of benzodiazepines may counteract the ceiling effect leading to potentiation of respiratory depression or sedative effects. High benzodiazepine levels have identified in 80% or more of buprenorphine fatalities.(6) Between 2002 and 2014, the number of patients receiving an opioid analgesic increased 8%, from 75 million to 81 million patients, and the number of patients receiving a benzodiazepine increased 31%, from 23 million to 30 million patients. During this time, the proportion of patients receiving concurrent therapy increased 31%, from 23 million to 30 million patients.(11) From 2004 to 2011, the rate of nonmedical use-related emergency room visits involving both opioids and benzodiazepines increased from 11 to 34.2 per 100,000 and drug overdose deaths involving both opioids and benzodiazepines increased from 0.6 to 1.7 per 100,000. The proportion of prescription opioid analgesic deaths which also involved benzodiazepines increased from 18% to 31% during this time.(12) A prospective observational cohort study in North Carolina found that the rates of overdose death among patients co-dispensed opioid analgesics and benzodiazepines were 10 times higher than patients receiving opioid analgesics alone.(13) A case-cohort study of VA data from 2004-2009 found that the risk of death from overdose increased with concomitant opioid analgesics and benzodiazepines. Compared to patients with no history of benzodiazepines, patients with a history of benzodiazepine use (hazard ratio [HR] = 2.33) and patients with a current benzodiazepine prescription (HR=3.86) had an increased risk of fatal overdose.(14) A study found that opioid analgesics contributed to 77% of deaths in which benzodiazepines were determined to be a cause of death and that benzodiazepines contributed to 30% of deaths in which opioid analgesics were determined to be a cause of death. This study also found that other CNS depressants (including barbiturates, antipsychotic and neuroleptic drugs, antiepileptic and antiparkinsonian drugs, anesthetics, autonomic nervous system drugs, and muscle relaxants) were contributory to death in many cases where opioid analgesics were also implicated.(15) A study found that alcohol was involved in 18.5% of opioid analgesic abuse-related ED visits and 22.1 percent of opioid analgesic-related deaths.(16) A study of 315,428 privately insured patients who filled at least one prescription for an opioid from 2001 to 2013 were enrolled in a retrospective study. Concurrent use of a benzodiazepine was recorded as having at least one day of overlap in a given calendar year. Baseline characteristics among opioid users with concurrent use of a benzodiazepine were older (44.5 v. 42.4, p<0.001), less likely to be men (35% v. 43%, p<0.001), and had a higher prevalence rate of every comorbidity examined (p<0.001). The proportion of opioid users with concurrent benzodiazepine use nearly doubled from 9% in 2001 to 17% in 2013. The primary outcome was an emergency room visit or inpatient admission for opioid overdose within a calendar year. Among all opioid users, the annual adjusted incidence for the primary outcome was 1.16% without concurrent benzodiazepine use compared to 2.42% with concurrent benzodiazepine use (OR 2.14; 95% CI 2.05-2.24; p<0.001). Intermittent opioid users (1.45% v. 1.02%; OR 1.42; 95% CI 1.33-1.51; p<0.001) and chronic opioid users (5.36% v. 3.13%; OR 1.81; 95% CI 1.67-1.96; p<0.001) also experienced a higher adjusted incidence of the primary outcome with concurrent benzodiazepine use compared to without concurrent benzodiazepine use, respectively.(17)

Buprenorphine; Pentazocine/Opioids

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Buprenorphine is a partial agonist at mu-opiate receptors, exhibiting a ceiling effect at which higher doses produce no further effect. Pentazocine is a mixed agonist-antagonist at opiate receptors.(1) Full mu-opioid agonists (e.g., morphine, methadone) continue to have increased effects at higher doses without ceiling effects.(2)

CLINICAL EFFECTS: Concurrent use of buprenorphine or pentazocine with other opioids in opioid dependent patients may result in withdrawal symptoms. Concurrent use in other patients may result in additive or decreased analgesia and decreased opioid side effects.

PREDISPOSING FACTORS: Patients dependent on opioids or who take higher dosages of opioids may be more likely to experience withdrawal symptoms with concurrent use.

PATIENT MANAGEMENT: Use buprenorphine and pentazocine with caution in patients maintained or dependent on other opioids and monitor for signs of withdrawal. In other patients, also monitor for changes in analgesic effects. The manufacturer of Sublocade states buprenorphine may precipitate opioid withdrawal in patients who are currently physically dependent on full opioid agonists. The risk of withdrawal may be increased if buprenorphine is given less than 6 hours after short-acting opioids (such as heroin, morphine) and less than 24 hours after long-acting opioids (such as methadone).(3)

DISCUSSION: Concurrent use of buprenorphine with other opioids in opioid dependent patients could result in withdrawal symptoms. Concurrent use in other patients may result in additive or decreased analgesia, decreased opioid side effects, and/or renarcotization.(2) In clinical trials, administration of buprenorphine injection produced withdrawal symptoms in patients maintained on methadone (30 mg daily) when administered 2 hours post-methadone,(4) but not when administered 20 hours post-methadone.(5) In another study, sublingual buprenorphine produced withdrawal symptoms in patients maintained on methadone. Symptoms were more pronounced in patients maintained on 60 mg daily doses than in patients maintained on 30 mg daily doses.(6) In a study of 10 patients maintained on methadone (100 mg daily), only three were able to tolerate escalating sublingual doses of buprenorphine/naloxone up to 32/8 mg. Split doses produced less withdrawal symptoms than full doses.(7) In a case report, a heroin-user maintained in a buprenorphine-maintenance program began stockpiling his buprenorphine instead of ingesting it and began using heroin. He then decided to re-initiate treatment on his own and ingested between 80 and 88 mg of buprenorphine over a two day period and experienced extreme withdrawal symptoms, despite restarting heroin during these symptoms. Methadone relieved his withdrawal symptoms.(8)

Opioids (Extended Release)/Antipsychotics; Phenothiazines

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Concurrent use of opioids and antipsychotics, including phenothiazine derivatives, may result in additive CNS depression.(1)

CLINICAL EFFECTS: Concurrent use of opioids and other CNS depressants, such as antipsychotics, including phenothiazine derivatives, may result in profound sedation, respiratory depression, coma, and/or death.(1)

PREDISPOSING FACTORS: Concurrent use of alcohol or other CNS depressants may increase the risk of adverse effects.

PATIENT MANAGEMENT: Limit prescribing opioid analgesics with CNS depressants such as antipsychotics, including phenothiazine derivatives, to patients for whom alternatives are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain.(1) If concurrent use is necessary, limit the dosages and duration of each drug to the minimum possible while achieving the desired clinical effect. If starting a CNS depressant (for an indication other than epilepsy) with an opioid analgesic, prescribe a lower initial dose of the CNS depressant than indicated in the absence of an opioid and titrate based upon clinical response. If an opioid analgesic is indicated in a patient already taking a CNS depressant, prescribe a lower dose of the opioid and titrate based upon clinical response.(1) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. The risk of opioid-related overdose or overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. Consider these risks when using concurrently with other agents that may cause CNS depression.(2) Monitor patients receiving concurrent therapy for unusual dizziness or lightheadedness, extreme sleepiness, slowed or difficult breathing, or unresponsiveness.(1) Discuss opioid reversal agents (e.g., naloxone, nalmefene) with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing an opioid reversal agent (e.g., naloxone, nalmefene) to patients prescribed medicines to treat OUD or opioid analgesics who are at increased risk of opioid overdose (such as those taking CNS depressants) and when a patient has household members/close contacts at risk for accidental overdose. Discuss the options for obtaining an opioid reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).(3)

DISCUSSION: A nested case-control study looked at the relationship between antipsychotic use and risk of acute respiratory failure. Current use of antipsychotics was associated with a 2.33-fold increase in risk of respiratory failure compared to no use of antipsychotics. The risk was also significantly increased in patients with recent use of antipsychotics (within the past 15-30 days, OR = 1.79) and recent past use (within 31-90 days OR = 1.41). The risk increased with higher doses and longer duration of use.(4) Between 2002 and 2014, the number of patients receiving an opioid analgesic increased 8%, from 75 million to 81 million patients, and the number of patients receiving a benzodiazepine increased 31%, from 23 million to 30 million patients. During this time, the proportion of patients receiving concurrent therapy increased 31%, from 23 million to 30 million patients.(5) From 2004 to 2011, the rate of nonmedical use-related emergency room visits involving both opioids and benzodiazepines increased from 11 to 34.2 per 100,000 and drug overdose deaths involving both opioids and benzodiazepines increased from 0.6 to 1.7 per 100,000. The proportion of prescription opioid analgesic deaths which also involved benzodiazepines increased from 18% to 31% during this time.(6) A prospective observational cohort study in North Carolina found that the rates of overdose death among patients co-dispensed opioid analgesics and benzodiazepines were 10 times higher than patients receiving opioid analgesics alone.(7) A case-cohort study of VA data from 2004-2009 found that the risk of death from overdose increased with concomitant opioid analgesics and benzodiazepines. Compared to patients with no history of benzodiazepines, patients with a history of benzodiazepine use (hazard ratio [HR] = 2.33) and patients with a current benzodiazepine prescription (HR=3.86) had an increased risk of fatal overdose.(8) A study found that opioid analgesics contributed to 77% of deaths in which benzodiazepines were determined to be a cause of death and that benzodiazepines contributed to 30% of deaths in which opioid analgesics were determined to be a cause of death. This study also found that other CNS depressants (including barbiturates, antipsychotic and neuroleptic drugs, antiepileptic and antiparkinsonian drugs, anesthetics, autonomic nervous system drugs, and muscle relaxants) were contributory to death in many cases where opioid analgesics were also implicated.(9) A study found that alcohol was involved in 18.5% of opioid analgesic abuse-related ED visits and 22.1 percent of opioid analgesic-related deaths.(10)

Opioids (Extended Release)/Cyclobenzaprine

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Concurrent use of opioids and cyclobenzaprine may result in additive CNS depression.(1)

CLINICAL EFFECTS: Concurrent use of opioids and other CNS depressants, such as cyclobenzaprine, may result in profound sedation, respiratory depression, coma, and/or death.(1)

PREDISPOSING FACTORS: Concurrent use of alcohol or other CNS depressants may increase the risk of adverse effects.

PATIENT MANAGEMENT: Limit prescribing opioid analgesics with CNS depressants such as muscle relaxants to patients for whom alternatives are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain.(1) If concurrent use is necessary, limit the dosages and duration of each drug to the minimum possible while achieving the desired clinical effect. If starting a CNS depressant (for an indication other than epilepsy) with an opioid analgesic, prescribe a lower initial dose of the CNS depressant than indicated in the absence of an opioid and titrate based upon clinical response. If an opioid analgesic is indicated in a patient already taking a CNS depressant, prescribe a lower dose of the opioid and titrate based upon clinical response.(1) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. The risk of opioid-related overdose or overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. Consider these risks when using concurrently with other agents that may cause CNS depression.(2) Monitor patients receiving concurrent therapy for unusual dizziness or lightheadedness, extreme sleepiness, slowed or difficult breathing, or unresponsiveness.(1) Discuss opioid reversal agents (e.g., naloxone, nalmefene) with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing an opioid reversal agent (e.g., naloxone, nalmefene) to patients prescribed medicines to treat OUD or opioid analgesics who are at increased risk of opioid overdose (such as those taking CNS depressants) and when a patient has household members/close contacts at risk for accidental overdose. Discuss the options for obtaining an opioid reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).(3)

DISCUSSION: Between 2002 and 2014, the number of patients receiving an opioid analgesic increased 8%, from 75 million to 81 million patients, and the number of patients receiving a benzodiazepine increased 31%, from 23 million to 30 million patients. During this time, the proportion of patients receiving concurrent therapy increased 31%, from 23 million to 30 million patients.(4) A retrospective cohort study compared the risk of opioid overdose associated with concomitant use of opioids and skeletal muscle relaxants versus opioid use alone. The study examined two types of opioid users (naive opioid use and prevalent opioid use) with and without exposure to skeletal muscle relaxants. The adjusted hazard ratios (HR) were 1.09 and 1.26 in the naive and prevalent opioid user cohorts, respectively, generating a combined estimate of 1.21. The risk increased with treatment duration (less than or equal to 14 days: 0.91; 15-60 days: 1.37; and greater than 60 days: 1.80) and for the use of baclofen and carisoprodol (HR 1.83 and 1.84, respectively). Elevated risk was associated with concomitant users with daily opioid dose greater than 50 mg and benzodiazepine use (HR 1.50 and 1.39, respectively).(5) From 2004 to 2011, the rate of nonmedical use-related emergency room visits involving both opioids and benzodiazepines increased from 11 to 34.2 per 100,000 and drug overdose deaths involving both opioids and benzodiazepines increased from 0.6 to 1.7 per 100,000. The proportion of prescription opioid analgesic deaths which also involved benzodiazepines increased from 18% to 31% during this time.(6) A prospective observational cohort study in North Carolina found that the rates of overdose death among patients co-dispensed opioid analgesics and benzodiazepines were 10 times higher than patients receiving opioid analgesics alone.(7) A case-cohort study of VA data from 2004-2009 found that the risk of death from overdose increased with concomitant opioid analgesics and benzodiazepines. Compared to patients with no history of benzodiazepines, patients with a history of benzodiazepine use (hazard ratio [HR] = 2.33) and patients with a current benzodiazepine prescription (HR=3.86) had an increased risk of fatal overdose.(8) A study found that opioid analgesics contributed to 77% of deaths in which benzodiazepines were determined to be a cause of death and that benzodiazepines contributed to 30% of deaths in which opioid analgesics were determined to be a cause of death. This study also found that other CNS depressants (including barbiturates, antipsychotic and neuroleptic drugs, antiepileptic and antiparkinsonian drugs, anesthetics, autonomic nervous system drugs, and muscle relaxants) were contributory to death in many cases where opioid analgesics were also implicated.(9) A study found that alcohol was involved in 18.5% of opioid analgesic abuse-related ED visits and 22.1 percent of opioid analgesic-related deaths.(10)

Opioids (Extended Release)/Muscle Relaxants

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Concurrent use of opioids and muscle relaxants may result in additive CNS depression.(1)

CLINICAL EFFECTS: Concurrent use of opioids and other CNS depressants, such as muscle relaxants, may result in profound sedation, respiratory depression, coma, and/or death.(1)

PREDISPOSING FACTORS: Concurrent use of alcohol or other CNS depressants may increase the risk of adverse effects.

PATIENT MANAGEMENT: Limit prescribing opioid analgesics with CNS depressants such as muscle relaxants to patients for whom alternatives are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain.(1) If concurrent use is necessary, limit the dosages and duration of each drug to the minimum possible while achieving the desired clinical effect. If starting a CNS depressant (for an indication other than epilepsy) with an opioid analgesic, prescribe a lower initial dose of the CNS depressant than indicated in the absence of an opioid and titrate based upon clinical response. If an opioid analgesic is indicated in a patient already taking a CNS depressant, prescribe a lower dose of the opioid and titrate based upon clinical response.(1) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. The risk of opioid-related overdose or overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. Consider these risks when using concurrently with other agents that may cause CNS depression.(2) Monitor patients receiving concurrent therapy for unusual dizziness or lightheadedness, extreme sleepiness, slowed or difficult breathing, or unresponsiveness.(1) Discuss opioid reversal agents (e.g., naloxone, nalmefene) with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing an opioid reversal agent (e.g., naloxone, nalmefene) to patients prescribed medicines to treat OUD or opioid analgesics who are at increased risk of opioid overdose (such as those taking CNS depressants) and when a patient has household members/close contacts at risk for accidental overdose. Discuss the options for obtaining an opioid reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).(3)

DISCUSSION: Between 2002 and 2014, the number of patients receiving an opioid analgesic increased 8%, from 75 million to 81 million patients, and the number of patients receiving a benzodiazepine increased 31%, from 23 million to 30 million patients. During this time, the proportion of patients receiving concurrent therapy increased 31%, from 23 million to 30 million patients.(4) A retrospective cohort study compared the risk of opioid overdose associated with concomitant use of opioids and skeletal muscle relaxants versus opioid use alone. The study examined two types of opioid users (naive opioid use and prevalent opioid use) with and without exposure to skeletal muscle relaxants. The adjusted hazard ratios (HR) were 1.09 and 1.26 in the naive and prevalent opioid user cohorts, respectively, generating a combined estimate of 1.21. The risk increased with treatment duration (less than or equal to 14 days: 0.91; 15-60 days: 1.37; and greater than 60 days: 1.80) and for the use of baclofen and carisoprodol (HR 1.83 and 1.84, respectively). Elevated risk was associated with concomitant users with daily opioid dose greater than 50 mg and benzodiazepine use (HR 1.50 and 1.39, respectively).(5) From 2004 to 2011, the rate of nonmedical use-related emergency room visits involving both opioids and benzodiazepines increased from 11 to 34.2 per 100,000 and drug overdose deaths involving both opioids and benzodiazepines increased from 0.6 to 1.7 per 100,000. The proportion of prescription opioid analgesic deaths which also involved benzodiazepines increased from 18% to 31% during this time.(6) A prospective observational cohort study in North Carolina found that the rates of overdose death among patients co-dispensed opioid analgesics and benzodiazepines were 10 times higher than patients receiving opioid analgesics alone.(7) A case-cohort study of VA data from 2004-2009 found that the risk of death from overdose increased with concomitant opioid analgesics and benzodiazepines. Compared to patients with no history of benzodiazepines, patients with a history of benzodiazepine use (hazard ratio [HR] = 2.33) and patients with a current benzodiazepine prescription (HR=3.86) had an increased risk of fatal overdose.(8) A study found that opioid analgesics contributed to 77% of deaths in which benzodiazepines were determined to be a cause of death and that benzodiazepines contributed to 30% of deaths in which opioid analgesics were determined to be a cause of death. This study also found that other CNS depressants (including barbiturates, antipsychotic and neuroleptic drugs, antiepileptic and antiparkinsonian drugs, anesthetics, autonomic nervous system drugs, and muscle relaxants) were contributory to death in many cases where opioid analgesics were also implicated.(9) A study found that alcohol was involved in 18.5% of opioid analgesic abuse-related ED visits and 22.1 percent of opioid analgesic-related deaths.(10)

Opioids (Extended Release)/Selected Stimulants

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Opioids and stimulants exhibit opposing effects on the CNS.

CLINICAL EFFECTS: Opposing CNS effects of opioids and stimulants may compromise the effectiveness of both agents and mask opioid overdose symptoms such as drowsiness and inability to focus

PREDISPOSING FACTORS: Concurrent use of alcohol or other CNS depressants may increase the risk of adverse effects.

PATIENT MANAGEMENT: Limit prescribing opioid analgesics with CNS stimulants such as amphetamines to patients for whom alternatives are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain. If concurrent use is necessary, limit the dosages and duration of each drug to the minimum possible while achieving the desired clinical effect. Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. The risk of opioid-related overdose or overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. Consider these risks when using concurrently with other agents that may cause CNS depression.(1) Monitor patients receiving concurrent therapy for signs of substance abuse. Monitor patients receiving concurrent therapy for unusual dizziness or lightheadedness, extreme sleepiness, slowed or difficult breathing, or unresponsiveness. Discuss opioid reversal agents (e.g., naloxone, nalmefene) with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing opioid reversal agents (e.g., naloxone, nalmefene) to patients prescribed medicines to treat OUD or opioid analgesics who are at increased risk of opioid overdose (such as those taking CNS depressants) and when a patient has household members/close contacts at risk for accidental overdose. Discuss the options for obtaining an opioid reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).

DISCUSSION: A total of 70,237 persons died from drug overdoses in the United States in 2017; approximately two thirds of these deaths involved an opioid.(2). The CDC analyzed 2016-2017 changes in age-adjusted death rates involving cocaine and psychostimulants by demographic characteristics, urbanization levels, U.S. Census region, 34 states, and the District of Columbia (DC). The CDC also examined trends in age-adjusted cocaine-involved and psychostimulant-involved death rates from 2003 to 2017 overall, as well as with and without co-involvement of opioids. Among all 2017 drug overdose deaths, 13,942 (19.8%) involved cocaine, and 10,333 (14.7%) involved psychostimulants. Death rates increased from 2016 to 2017 for both drug categories across demographic characteristics, urbanization levels, Census regions, and states. In 2017, opioids were involved in 72.7% and 50.4% of cocaine-involved and psychostimulant-involved overdoses, respectively, and the data suggest that increases in cocaine-involved overdose deaths from 2012 to 2017 were driven primarily by synthetic opioids.(3) There was opioid co-involvement in 72.7 percent of cocaine and 50.4 percent of stimulant-involved overdose deaths. This was largely driven by synthetic opioids such as fentanyl. However, stimulant-involved overdose without opioid co-involvement is also increasing.(2)

Opioids (Extended Release)/Sleep Drugs

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Concurrent use of opioids and sleep drugs may result in additive CNS depression and sleep-related disorders.(1)

CLINICAL EFFECTS: Concurrent use of opioids and other CNS depressants, such as sleep drugs, may result in profound sedation, respiratory depression, coma, and/or death.(1) Concurrent use of opioids with eszopiclone, zaleplon, or zolpidem may increase the risk of sleep-related disorders including central sleep apnea and sleep-related hypoxemia and complex sleep behaviors like sleepwalking, sleep driving, and other activities while not fully awake. Rarely, serious injuries or death have resulted from complex sleep behaviors.(2)

PREDISPOSING FACTORS: Concurrent use of alcohol or other CNS depressants may increase the risk of adverse effects.

PATIENT MANAGEMENT: Limit prescribing opioid analgesics with CNS depressants such as sleep drugs to patients for whom alternatives are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain.(1) If concurrent use is necessary, limit the dosages and duration of each drug to the minimum possible while achieving the desired clinical effect. If starting a CNS depressant (for an indication other than epilepsy) with an opioid analgesic, prescribe a lower initial dose of the CNS depressant than indicated in the absence of an opioid and titrate based upon clinical response. If an opioid analgesic is indicated in a patient already taking a CNS depressant, prescribe a lower dose of the opioid and titrate based upon clinical response.(1) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. The risk of opioid-related overdose or overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. Consider these risks when using concurrently with other agents that may cause CNS depression.(3) Monitor patients receiving concurrent therapy for unusual dizziness or lightheadedness, extreme sleepiness, slowed or difficult breathing, or unresponsiveness.(1) Eszopiclone, zaleplon, and zolpidem are contraindicated in patients who have had a previous episode of complex sleep behavior.(2) Discuss opioid reversal agents (e.g., naloxone, nalmefene) with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing an opioid reversal agent (e.g., naloxone, nalmefene) to patients prescribed medicines to treat OUD or opioid analgesics who are at increased risk of opioid overdose (such as those taking CNS depressants) and when a patient has household members/close contacts at risk for accidental overdose. Discuss the options for obtaining an opioid reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).(4)

DISCUSSION: Between 2002 and 2014, the number of patients receiving an opioid analgesic increased 8%, from 75 million to 81 million patients, and the number of patients receiving a benzodiazepine increased 31%, from 23 million to 30 million patients. During this time, the proportion of patients receiving concurrent therapy increased 31%, from 23 million to 30 million patients.(5) From 2004 to 2011, the rate of nonmedical use-related emergency room visits involving both opioids and benzodiazepines increased from 11 to 34.2 per 100,000 and drug overdose deaths involving both opioids and benzodiazepines increased from 0.6 to 1.7 per 100,000. The proportion of prescription opioid analgesic deaths which also involved benzodiazepines increased from 18% to 31% during this time.(6) A prospective observational cohort study in North Carolina found that the rates of overdose death among patients co-dispensed opioid analgesics and benzodiazepines were 10 times higher than patients receiving opioid analgesics alone.(7) A case-cohort study of VA data from 2004-2009 found that the risk of death from overdose increased with concomitant opioid analgesics and benzodiazepines. Compared to patients with no history of benzodiazepines, patients with a history of benzodiazepine use (hazard ratio [HR] = 2.33) and patients with a current benzodiazepine prescription (HR=3.86) had an increased risk of fatal overdose.(8) A study found that opioid analgesics contributed to 77% of deaths in which benzodiazepines were determined to be a cause of death and that benzodiazepines contributed to 30% of deaths in which opioid analgesics were determined to be a cause of death. This study also found that other CNS depressants (including barbiturates, antipsychotic and neuroleptic drugs, antiepileptic and antiparkinsonian drugs, anesthetics, autonomic nervous system drugs, and muscle relaxants) were contributory to death in many cases where opioid analgesics were also implicated.(9) A study found that alcohol was involved in 18.5% of opioid analgesic abuse-related ED visits and 22.1 percent of opioid analgesic-related deaths.(10) As of April 2019, the FDA had identified 66 cases of complex sleep behaviors with eszopiclone, zaleplon, or zolpidem, of which 20 cases resulted in death and the remainder resulted in serious injuries. It was not reported how many of the cases involved concomitant use of other CNS depressants.(2)

Opioids (Extended Release)/Ziprasidone

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Concurrent use of opioids and ziprasidone may result in additive CNS depression.(1)

CLINICAL EFFECTS: Concurrent use of opioids and other CNS depressants, such as ziprasidone, may result in profound sedation, respiratory depression, coma, and/or death.(1)

PREDISPOSING FACTORS: Concurrent use of alcohol or other CNS depressants may increase the risk of adverse effects.

PATIENT MANAGEMENT: Limit prescribing opioid analgesics with CNS depressants such as ziprasidone to patients for whom alternatives are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain.(1) If concurrent use is necessary, limit the dosages and duration of each drug to the minimum possible while achieving the desired clinical effect. If starting a CNS depressant (for an indication other than epilepsy) with an opioid analgesic, prescribe a lower initial dose of the CNS depressant than indicated in the absence of an opioid and titrate based upon clinical response. If an opioid analgesic is indicated in a patient already taking a CNS depressant, prescribe a lower dose of the opioid and titrate based upon clinical response.(1) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. The risk of opioid-related overdose or overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. Consider these risks when using concurrently with other agents that may cause CNS depression.(2) Monitor patients receiving concurrent therapy for unusual dizziness or lightheadedness, extreme sleepiness, slowed or difficult breathing, or unresponsiveness.(1) Discuss opioid reversal agents (e.g., naloxone, nalmefene) with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing an opioid reversal agent (e.g., naloxone, nalmefene) to patients prescribed medicines to treat OUD or opioid analgesics who are at increased risk of opioid overdose (such as those taking CNS depressants) and when a patient has household members/close contacts at risk for accidental overdose. Discuss the options for obtaining an opioid reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).(3)

DISCUSSION: A nested case-control study looked at the relationship between antipsychotic use and risk of acute respiratory failure. Current use of antipsychotics was associated with a 2.33-fold increase in risk of respiratory failure compared to no use of antipsychotics. The risk was also significantly increased in patients with recent use of antipsychotics (within the past 15-30 days, OR = 1.79) and recent past use (within 31-90 days OR = 1.41). The risk increased with higher doses and longer duration of use.(4) Between 2002 and 2014, the number of patients receiving an opioid analgesic increased 8%, from 75 million to 81 million patients, and the number of patients receiving a benzodiazepine increased 31%, from 23 million to 30 million patients. During this time, the proportion of patients receiving concurrent therapy increased 31%, from 23 million to 30 million patients.(5) From 2004 to 2011, the rate of nonmedical use-related emergency room visits involving both opioids and benzodiazepines increased from 11 to 34.2 per 100,000 and drug overdose deaths involving both opioids and benzodiazepines increased from 0.6 to 1.7 per 100,000. The proportion of prescription opioid analgesic deaths which also involved benzodiazepines increased from 18% to 31% during this time.(6) A prospective observational cohort study in North Carolina found that the rates of overdose death among patients co-dispensed opioid analgesics and benzodiazepines were 10 times higher than patients receiving opioid analgesics alone.(7) A case-cohort study of VA data from 2004-2009 found that the risk of death from overdose increased with concomitant opioid analgesics and benzodiazepines. Compared to patients with no history of benzodiazepines, patients with a history of benzodiazepine use (hazard ratio [HR] = 2.33) and patients with a current benzodiazepine prescription (HR=3.86) had an increased risk of fatal overdose.(8) A study found that opioid analgesics contributed to 77% of deaths in which benzodiazepines were determined to be a cause of death and that benzodiazepines contributed to 30% of deaths in which opioid analgesics were determined to be a cause of death. This study also found that other CNS depressants (including barbiturates, antipsychotic and neuroleptic drugs, antiepileptic and antiparkinsonian drugs, anesthetics, autonomic nervous system drugs, and muscle relaxants) were contributory to death in many cases where opioid analgesics were also implicated.(9) A study found that alcohol was involved in 18.5% of opioid analgesic abuse-related ED visits and 22.1 percent of opioid analgesic-related deaths.(10)

Opioids (Ir & Er)/Gabapentinoids

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Opioid-induced reduction in GI motility may increase the absorption of gabapentin and pregabalin.(1) Gabapentin and pregabalin may reverse opioid-induced tolerance of respiratory depression.(2) Concurrent use may result in profound sedation, respiratory depression, coma, and/or death.(3)

CLINICAL EFFECTS: Concurrent use of opioids may result in elevated levels of and toxicity from gabapentin and pregabalin, including profound sedation, respiratory depression, coma, and/or death.(1-7)

PREDISPOSING FACTORS: Patients who are elderly, are taking other CNS depressants, have decreased renal function, and/or have conditions that reduce lung function (e.g. Chronic Obstructive Pulmonary Disease [COPD]) may be at a higher risk of this interaction.

PATIENT MANAGEMENT: Limit prescribing opioid analgesics and gabapentinoids to patients for whom alternatives are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain.(1) If concurrent use is necessary, limit the dosages and duration of each drug to the minimum possible while achieving the desired clinical effect. If starting a gabapentinoid with an opioid analgesic, prescribe a lower initial dose of the gabapentinoid than indicated in the absence of an opioid and titrate based upon clinical response. If an opioid analgesic is indicated in a patient already taking a gabapentinoid, prescribe a lower dose of the opioid and titrate based upon clinical response.(1) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. The risk of opioid-related overdose or overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. Consider these risks when using concurrently with other agents that may cause CNS depression.(8) Monitor patients receiving concurrent therapy for unusual dizziness or lightheadedness, extreme sleepiness, slowed or difficult breathing, or unresponsiveness.(1) Discuss opioid reversal agents (e.g., naloxone, nalmefene) with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing an opioid reversal agent (e.g., naloxone, nalmefene) to patients prescribed medicines to treat OUD or opioid analgesics who are at increased risk of opioid overdose (such as those taking CNS depressants) and when a patient has household members/close contacts at risk for accidental overdose. Discuss the options for obtaining an opioid reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).(9)

DISCUSSION: In a study in 12 healthy males, administration of a single dose of morphine (60 mg sustained release) increased the area-under-curve (AUC) of a single dose of gabapentin (600 mg) by 44%.(1,3,4) There were no affects on the pharmacokinetics of morphine.(1,3,4) The combination of gabapentin plus morphine increased pain tolerance over the combination of morphine plus placebo. Side effects were not significantly different between morphine plus placebo and morphine plus gabapentin.(1) A retrospective, case-control study of opioid users in Ontario, Canada between August 1, 1997 and December 31, 2013 who died of an opioid-related cause matched cases to up to 4 controls who also used opioids. Use of gabapentin in the 120 days prior to death resulted in a significant increase in odds of opioid-related death (OR 1.99, CI=1.61-2.47, p<0.001), compared to opioid use alone. Use of moderate dose (900 mg to 1,799 mg daily) or high dose (>= 1,800 mg daily) gabapentin increased the odds of opioid-related death 60% compared to opioid use without gabapentin. Review of gabapentin prescriptions from calendar year 2013 found that 46% of gabapentin users received at least 1 opioid prescription.(3) Among 49 case reports submitted to FDA over a 5 year period (2012-2017), 12 people died from respiratory depression with gabapentinoids. Two randomized, double-blind, placebo-controlled clinical trials in healthy people, three observational studies, and several studies in animals were reviewed. A trial showed that using pregabalin alone and using it with an opioid pain reliever can depress breathing function. Three observational studies showed a relationship between gabapentinoids given before surgery and respiratory depression occurring after surgery. Several animal studies also showed that pregabalin plus opioids can depress respiratory function.(7) A retrospective cohort study evaluated the risk of mortality among Medicare beneficiaries aged 65 and older who were taking gabapentin with or without concurrent use of opioids. All-cause mortality in gabapentin users compared to duloxetine users was 12.16 per 1,000 person years vs. 9.94 per 1,000 person years, respectively. Adjusted for covariates, the risk of all-cause mortality among gabapentin users on high-dose opioids was more than double the control group (hazard ratio (HR) 2.03, CI=1.19-3.46).(10)

Selected Opioids (Extended Release)/Metaxalone

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Concurrent use of opioids and metaxalone may result in additive CNS depression.(1)

CLINICAL EFFECTS: Concurrent use of opioids and other CNS depressants, such as the muscle relaxant metaxalone, may result in profound sedation, respiratory depression, coma, and/or death.(1)

PREDISPOSING FACTORS: Concurrent use of alcohol or other CNS depressants may increase the risk of adverse effects.

PATIENT MANAGEMENT: Limit prescribing opioid analgesics with CNS depressants such as the muscle relaxant metaxalone to patients for whom alternatives are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain.(1) If concurrent use is necessary, limit the dosages and duration of each drug to the minimum possible while achieving the desired clinical effect. If starting a CNS depressant (for an indication other than epilepsy) with an opioid analgesic, prescribe a lower initial dose of the CNS depressant than indicated in the absence of an opioid and titrate based upon clinical response. If an opioid analgesic is indicated in a patient already taking a CNS depressant, prescribe a lower dose of the opioid and titrate based upon clinical response.(1) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. The risk of opioid-related overdose or overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. Consider these risks when using concurrently with other agents that may cause CNS depression.(2) Monitor patients receiving concurrent therapy for unusual dizziness or lightheadedness, extreme sleepiness, slowed or difficult breathing, or unresponsiveness.(1) Discuss opioid reversal agents (e.g., naloxone, nalmefene) with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing an opioid reversal agent (e.g., naloxone, nalmefene) to patients prescribed medicines to treat OUD or opioid analgesics who are at increased risk of opioid overdose (such as those taking CNS depressants) and when a patient has household members/close contacts at risk for accidental overdose. Discuss the options for obtaining an opioid reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).(3)

DISCUSSION: Between 2002 and 2014, the number of patients receiving an opioid analgesic increased 8%, from 75 million to 81 million patients, and the number of patients receiving a benzodiazepine increased 31%, from 23 million to 30 million patients. During this time, the proportion of patients receiving concurrent therapy increased 31%, from 23 million to 30 million patients.(4) A retrospective cohort study compared the risk of opioid overdose associated with concomitant use of opioids and skeletal muscle relaxants versus opioid use alone. The study examined two types of opioid users (naive opioid use and prevalent opioid use) with and without exposure to skeletal muscle relaxants. The adjusted hazard ratios (HR) were 1.09 and 1.26 in the naive and prevalent opioid user cohorts, respectively, generating a combined estimate of 1.21. The risk increased with treatment duration (less than or equal to 14 days: 0.91; 15-60 days: 1.37; and greater than 60 days: 1.80) and for the use of baclofen and carisoprodol (HR 1.83 and 1.84, respectively). Elevated risk was associated with concomitant users with daily opioid dose greater than 50 mg and benzodiazepine use (HR 1.50 and 1.39, respectively).(5) From 2004 to 2011, the rate of nonmedical use-related emergency room visits involving both opioids and benzodiazepines increased from 11 to 34.2 per 100,000 and drug overdose deaths involving both opioids and benzodiazepines increased from 0.6 to 1.7 per 100,000. The proportion of prescription opioid analgesic deaths which also involved benzodiazepines increased from 18% to 31% during this time.(6) A prospective observational cohort study in North Carolina found that the rates of overdose death among patients co-dispensed opioid analgesics and benzodiazepines were 10 times higher than patients receiving opioid analgesics alone.(7) A case-cohort study of VA data from 2004-2009 found that the risk of death from overdose increased with concomitant opioid analgesics and benzodiazepines. Compared to patients with no history of benzodiazepines, patients with a history of benzodiazepine use (hazard ratio [HR] = 2.33) and patients with a current benzodiazepine prescription (HR=3.86) had an increased risk of fatal overdose.(8) A study found that opioid analgesics contributed to 77% of deaths in which benzodiazepines were determined to be a cause of death and that benzodiazepines contributed to 30% of deaths in which opioid analgesics were determined to be a cause of death. This study also found that other CNS depressants (including barbiturates, antipsychotic and neuroleptic drugs, antiepileptic and antiparkinsonian drugs, anesthetics, autonomic nervous system drugs, and muscle relaxants) were contributory to death in many cases where opioid analgesics were also implicated.(9) A study found that alcohol was involved in 18.5% of opioid analgesic abuse-related ED visits and 22.1 percent of opioid analgesic-related deaths.(10)

Selected Opioids/Barbiturates; Phenobarbital; Primidone

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: There are two mechanisms involved in this interaction. Pharmacokinetic: alfentanil, benzhydrocodone, buprenorphine, fentanyl, hydrocodone, meperidine, oxycodone, and sufentanil are primarily metabolized by CYP3A4/5 and glucuronidation pathways.(1-8) Phenobarbital is an inducer of these pathways. Pharmacodynamic: both opioids and barbiturates are associated with respiratory depression; these effects may be additive.(1,3,9) Benzhydrocodone is a prodrug of hydrocodone.(2) Primidone is metabolized to phenobarbital.

CLINICAL EFFECTS: Short term or intermittent use of phenobarbital and opioids metabolized by CYP3A4 may be associated with respiratory suppression or other CNS depression. Continuous, longer term use of phenobarbital may result in decreased levels and effectiveness of the opioid. Induction of meperidine metabolism may result in an increase in levels of normeperidine, the toxic metabolite of meperidine, resulting in a higher risk of excitatory effects, including hallucinations, tremors, and seizures.(6,10)

PREDISPOSING FACTORS: Patients with a history of alcohol or sedative abuse may be at risk for relapse and overuse or abuse of prescribed phenobarbital.(1,3,5,11) Individuals with significant obstructive pulmonary disease, the elderly, and debilitated patients are at greater risk for respiratory depression from either agent.(1,3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Patients on chronic therapy with phenobarbital who are newly starting opioids metabolized by CYP3A4 may need higher than usual doses of the opioid for analgesia or opioid maintenance.(1,3,12) Opioid-treated patients newly started on phenobarbital should be monitored initially for additive CNS sedation or respiratory depression, particularly when predisposing factors (e.g. COPD, sleep apnea, debilitation, elderly) are present. Continued use of phenobarbital leads to induction of the opioids' metabolism. The onset is gradual and may not peak for several weeks. Monitor patient for possible loss of efficacy or opioid withdrawal. If a patient has been maintained on concurrent treatment with an opioid metabolized by CYP3A4 and phenobarbital, and the phenobarbital is discontinued, opioid levels will gradually rise as induction effects diminish. Monitor for increased opioid effects and adjust the dose accordingly.(1,3,12) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. The risk of opioid-related overdose or overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. Consider these risks when using concurrently with other agents that may cause CNS depression.(13) For patients receiving opioid maintenance treatment, it would be prudent to assure all controlled substance prescriptions are approved or written by the opioid provider. Discuss opioid reversal agents (e.g., naloxone, nalmefene) with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing an opioid reversal agent (e.g., naloxone, nalmefene) to patients prescribed medicines to treat OUD or opioid analgesics who are at increased risk of opioid overdose (such as those taking CNS depressants) and when a patient has household members/close contacts at risk for accidental overdose. Discuss the options for obtaining an opioid reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).(14)

DISCUSSION: Alfentanil, benzhydrocodone, fentanyl, hydrocodone, meperidine, oxycodone, and sufentanil are metabolized by CYP3A4, and barbiturates, phenobarbital, and primidone would be expected to induce their metabolism.(1,2,4-6) Newer metabolites and minor metabolic pathways for buprenorphine have been recently described. Phenobarbital, an inducer of multiple enzyme pathways (e.g. CYP2B, CYP2C, CYP3A and UGT) could potentially lower systemic buprenorphine levels via major and minor pathways.(12)

Selected Opioids/Selected Strong Cyp3a4 Inducers

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Strong inducers of CYP3A4 may induce the metabolism of alfentanil, benzhydrocodone, buprenorphine,(1) fentanyl, hydrocodone, meperidine,(2-4) morphine,(5) oxycodone, papaveretum, and sufentanil.(6)

CLINICAL EFFECTS: Concurrent use of a strong CYP3A4 inducer may result in decreased levels of alfentanil, benzhydrocodone, buprenorphine, fentanyl, hydrocodone, meperidine, morphine, oxycodone, papaveretum, and sufentanil, which may result in decreased effectiveness and may precipitate withdrawal symptoms.(1-6) Induction of meperidine metabolism may result in an increase in levels of normeperidine, the toxic metabolite of meperidine, resulting in a higher risk of excitatory effects, including hallucinations, tremors, and seizures.(2,3)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Patients maintained on alfentanil, benzhydrocodone, buprenorphine, fentanyl, hydrocodone, meperidine, morphine, oxycodone, papaveretum, and sufentanil may require dosage adjustments if a strong CYP3A4 inducer is initiated or discontinued. The effects of the interaction may last for several weeks after the discontinuation of the inducer. Patients who transfer to Sublocade (extended release subcutaneous syringe buprenorphine) from transmucosal buprenorphine used concomitantly with CYP3A4 inducers should be monitored to ensure that the plasma buprenorphine level produced by Sublocade is adequate. If patients already on Sublocade require newly-initiated treatment with CYP3A4 inducer, the patient should be monitored for withdrawal. If the dose of Sublocade is not adequate in the absence of the concomitant medication, and the concomitant medication cannot be reduced or discontinued, the patient should be transitioned back to a formulation of buprenorphine that permits dose adjustment. If a patient has been stabilized on Sublocade with a CYP3A4 inducer and the concomitant medication is discontinued, the patient should be monitored for signs and symptoms of over-medication. Within 2 weeks of Sublocade administration, if the dose provided by Sublocade is excessive in the absence of the concomitant inducer, it may be necessary to remove the Sublocade and treat the patient with a formulation of buprenorphine that permits dose adjustments.(15) The manufacturer of sufentanil sublingual tablets states that if concomitant use with CYP3A4 inducers is necessary, consider use of an alternate agent that allows dose adjustment.(6)

DISCUSSION: In a study in 12 opoid-dependent patients, rifampin (600 mg daily) decreased the area-under-curve (AUC) of buprenorphine by 70%. Half of the subjects experienced withdrawal symptoms. When compared to historical values, there was no effect on rifampin levels.(1) In a study of four healthy volunteers, phenytoin increased meperidine clearance from 1017 +/- 225 ml/min (mean +/- SD) to 1280 +/- 130 ml/min and decreased half-life from 6.4 hours to 4.3 hours. Phenytoin also increased normeperidine AUC by 1.53-fold after IV meperidine and by 1.25-fold after oral meperidine.(3) In a study in 10 healthy subjects, pretreatment with rifampin (600 mg daily) for 13 days decreased the area-under-curve (AUC) and maximum concentration (Cmax) of a single dose of morphine by 28% and 41%, respectively. The AUCs of morphine-3-glucuronide and morphine-6-glucuronide were proportionally decreased as well. Following rifampin pretreatment, no analgesic effects of morphine were seen.(5) In a randomized controlled trial of 12 healthy participants St. John's wort decreased the oxycodone AUC by 50%, shortened the oxycodone elimination half-life, and decreased the self-reported drug effect of oxycodone compared to placebo.(7) In a study in 12 healthy subjects, pretreatment with rifampin had no effect on fentanyl Cmax or time to Cmax (Tmax) after administration of oral transmucosal fentanyl. However, fentanyl AUC decreased 62%.(8) In a study in 9 healthy subjects, rifampin increased the clearance of alfentanil by 169%. Alfentanil half-life decreased 61%.(9) In a study of patients undergoing craniotomy, higher fentanyl maintenance doses were required in patients receiving carbamazepine and phenytoin compared to control subjects not receiving enzyme-inducing agents.(10) There are case reports of decreased levels and effectiveness of oxycodone with concurrent phenytoin(11) and rifampin(12) and with concurrent fentanyl and rifampin.(13-14) Selected strong CYP3A4 inducers linked to this monograph include: apalutamide, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenytoin, rifampin, rifapentine, and St. John's Wort.

Buprenorphine is contraindicated in patients with known hypersensitivity to the drug or any components of the formulation. In addition, buprenorphine/naloxone is contraindicated in patients with known hypersensitivity to naloxone. Buprenorphine formulations labeled for analgesic use are contraindicated in patients with known or suspected GI obstruction (including paralytic ileus), substantial respiratory depression, or acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment.

• Acute asthma attack
• Paralytic ileus

• Acute pancreatitis
• Alcohol intoxication
• Coma
• Congenital long QT syndrome
• Drug abuse
• Exacerbation of chronic obstructive pulmonary disease
• Fever
• Gastrointestinal obstruction
• History of opioid overdose
• Hypotension
• Intracranial hypertension
• Myasthenia gravis
• Respiratory depression
• Sleep apnea

• Adrenocortical insufficiency
• Alcohol withdrawal delirium
• Biliary tract disorder
• Cachexia
• Constipation
• Cor pulmonale
• Debilitation
• Disease of liver
• Lower seizure threshold
• Seizure disorder
• Untreated hypothyroidism
• Urinary retention

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More Frequent

• Pruritus of skin

Less Frequent

• Back pain
• Dehydration
• Dyspnea
• Infection
• Respiratory depression
• Syncope

Rare or Very Rare

• Accidental fall
• Adrenocortical insufficiency
• Anaphylaxis
• Androgen deficiency
• Angioedema
• Bronchospastic pulmonary disease
• Disorder of adrenal gland
• Drug dependence
• Hypersensitivity drug reaction
• Ileus
• Severe hypotension
• Sleep apnea
• Urticaria

More Frequent

• Constipation
• Dizziness
• Drowsy
• Erythema
• Headache disorder
• Nausea
• Skin rash
• Vomiting
• Xerostomia

Less Frequent

• Abdominal pain with cramps
• Anorexia
• Application site skin reactions
• Chest pain
• Cough
• Depression
• Diarrhea
• Dyspepsia
• Fatigue
• Fever
• Flu-like symptoms
• General weakness
• Hyperhidrosis
• Hypoesthesia
• Insomnia
• Paresthesia
• Pharyngitis
• Symptoms of anxiety
• Tremor

Rare or Very Rare

• Altered consciousness
• Chills
• Erectile dysfunction
• Hypoglycemic disorder
• Infertility
• Libido changes
• Nervousness
• Opioid induced allodynia
• Opioid induced hyperalgesia
• Orthostatic hypotension
• Palpitations
• Rhinitis
• Vasodilation of blood vessels
• Visual changes

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Buprenorphine is distributed into milk in humans. In 2 studies that included 13 nursing women receiving maintenance treatment with sublingual buprenorphine (2.4-24 mg daily) for opiate dependence, buprenorphine and its metabolite norbuprenorphine were present in low concentrations in milk and in the breast-fed infant's urine; the infants were exposed to less than 1% of the maternal daily buprenorphine dosage. In the first study in 6 women receiving buprenorphine (median dosage of 0.29 mg/kg daily) at 5-8 days postpartum, breast milk provided a median infant dosage of 0.42 mcg/kg daily of buprenorphine and 0.33 mcg/kg daily of norbuprenorphine (0.2 and 0.12%, respectively, of the maternal weight-adjusted dosage). In the other study in 7 women receiving buprenorphine (median dosage of 7 mg daily) at an average of 1.12 months postpartum, mean milk concentrations of buprenorphine and norbuprenorphine were 3.65 and 1.94 mcg/L, respectively; based on the results of this study, an exclusively breast-fed infant consuming 150 mL/kg daily of milk would receive a mean estimated dosage of 0.55 mcg/kg daily of buprenorphine and 0.29 mcg/kg daily of norbuprenorphine (0.38 and 0.18%, respectively, of the maternal weight-adjusted dosage). Adverse reactions in nursing infants were not observed.

Experts recommend that women who are stable on buprenorphine or buprenorphine/naloxone treatment for opiate dependence, are not using other illicit drugs, and have no contraindications to nursing be encouraged to breast-feed their infants; to lower the risk of return to substance use, women receiving buprenorphine should be encouraged to continue treatment during the postpartum period. Breast-feeding has been associated with decreased severity of neonatal opiate withdrawal syndrome, decreased need for pharmacotherapy, and shorter hospital stays for the neonate. The manufacturers of buprenorphine-containing preparations used for treatment of opiate dependence state that developmental and health benefits of breast-feeding should be considered along with the mother's clinical need for buprenorphine or buprenorphine/naloxone and any potential adverse effects on the breast-fed child from the drug or from the underlying maternal condition. Because of the potential for serious adverse reactions, including excess sedation and respiratory depression in nursing infants, the manufacturers of buprenorphine preparations labeled for use as analgesics state that women should be advised not to nurse an infant while receiving the drug. Infants who are exposed to buprenorphine through breast milk should be monitored for excess sedation and respiratory depression.

Symptoms of withdrawal can occur in opiate-dependent infants when maternal administration of opiates is discontinued or breast-feeding is stopped.

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