Ambisome (amphotericin B liposome)

Amphotericin B is available as conventional amphotericin B (formulated with sodium desoxycholate) or amphotericin B liposomal (AmBisome(R)); dosage is expressed as amphotericin B.

Dosage of amphotericin B varies depending on whether the drug is administered as conventional amphotericin B (formulated with sodium desoxycholate) or amphotericin B liposomal. Dosage recommendations for the specific formulation being administered should be followed.

No dosing information is available for this tab.

Systematic drug interaction studies have not been performed to date using amphotericin B liposomal. The fact that drug interactions reported with conventional IV amphotericin B could also occur with the lipid formulation of the drug should be considered.

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

Selected Nephrotoxic Agents/Bacitracin

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: Bacitracin may cause renal failure due to glomerular and tubular necrosis. Concurrent administration of other nephrotoxic agents may result in additive renal toxicity.(1-3)

CLINICAL EFFECTS: Concurrent use of bacitracin with other potentially nephrotoxic agents may result in renal toxicity.(1-3)

PREDISPOSING FACTORS: Dehydration and high-dose bacitracin may predispose to adverse renal effects.(1)

PATIENT MANAGEMENT: Health Canada states that bacitracin is contraindicated in patients with renal impairment, including those taking other nephrotoxic drugs.(1) The Canadian and US manufacturers of bacitracin state that concomitant use of bacitracin with other potentially nephrotoxic agents should be avoided.(2,3)

DISCUSSION: Renal impairment is a major toxicity of bacitracin. Cases of nephrotoxicity have been reported when bacitracin was used off-label.(1-3)

Selected Nephrotoxic Agents/Cidofovir

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: Cidofovir is nephrotoxic. Concurrent administration of other nephrotoxic agents may result in additive or synergistic effects on renal function.(1-3)

CLINICAL EFFECTS: Concurrent use of cidofovir with nephrotoxic agents such as adefovir, intravenous aminoglycosides, amphotericin B, foscarnet, intravenous pentamidine, tenofovir, vancomycin, voclosporin and non-steroidal anti-inflammatory agents may result in renal toxicity.(1-3) Other nephrotoxic agents include capreomycin, cisplatin, gallium nitrate, high-dose methotrexate, and streptozocin.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The Australian,(1) UK,(2) and US(3) manufacturers of cidofovir state that concurrent administration of potentially nephrotoxic agents such as adefovir, intravenous aminoglycosides, amphotericin B, foscarnet, intravenous pentamidine, tenofovir, vancomycin, voclosporin and non-steroidal anti-inflammatory agents may result in renal toxicity.(1-3) Other nephrotoxic agents include capreomycin, cisplatin, gallium nitrate, high-dose methotrexate, and streptozocin. These agents should be discontinued at least 7 days before the administration of cidofovir.

DISCUSSION: The safety of cidofovir has not been studied in patients receiving other known potentially nephrotoxic agents. Renal impairment is the major toxicity of cidofovir.(1-3)

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

Amphotericin B/Corticosteroids; Corticotropin (ACTH)

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

MECHANISM OF ACTION: Corticosteroids and corticotropin may potentiate potassium excretion and overload salt and water retention.(1)

CLINICAL EFFECTS: Concurrent use of amphotericin b with corticosteroids or corticotropin may potentiate amphotericin b-induced hypokalemia, thereby predisposing patients to cardiac dysfunction.(1-2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of amphotericin b states that concurrent use of corticosteroids or corticotropin should be avoided unless absolutely necessary to avoid side effects. If concurrent use is necessary, serum electrolytes and cardiac function must be monitored closely.(1)

DISCUSSION: There are four case reports of cardiac enlargement, hypokalemia, and hypernatremia from concurrent use of amphotericin b and corticosteroids.(2)

Amphotericin B/Cyclosporine

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

MECHANISM OF ACTION: Additive nephrotoxicity is most likely mechanism.

CLINICAL EFFECTS: May observe enhanced nephrotoxicity of one or both drugs.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Administer this combination cautiously. Monitoring of renal function is indicated. A decrease in cyclosporine dose will result in rapid reversal of cyclosporine-induced increases in creatinine. Holding the cyclosporine dose until serum levels are less than 150 ng/ml may reduce the likelihood of renal toxicity.

DISCUSSION: Documentation is lacking; however, if an interaction occurs, the consequences could be severe.

Amphotericin B/Digitalis Glycosides

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

MECHANISM OF ACTION: Amphotericin B may cause hypokalemia which can predispose patients to digitalis toxicity.

CLINICAL EFFECTS: Possible potentiation of digitalis effects. Symptoms of digoxin toxicity can include anorexia, nausea, vomiting, headache, fatigue, malaise, drowsiness, generalized muscle weakness, disorientation, hallucinations, visual disturbances, and arrhythmias.

PREDISPOSING FACTORS: Low body weight, advanced age, impaired renal function, hypokalemia, hypercalcemia, and/or hypomagnesemia may increase the risk of digoxin toxicity.

PATIENT MANAGEMENT: Monitor potassium levels carefully in patients using these agents concomitantly. Correct potassium deficits promptly.

DISCUSSION: Amphotericin B induced hypokalemia is a well known drug side effect.

Myelosuppressives; Immunomodulators/Sodium Iodide I 131

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

MECHANISM OF ACTION: Sodium iodide I 131 can cause depression of the hematopoetic system. Myelosuppressives and immunomodulators also suppress the immune system.(1)

CLINICAL EFFECTS: Concurrent use of sodium iodide I 131 with agents that cause bone marrow depression, including myelosuppressives or immunomodulators, may result in an enhanced risk of hematologic disorders, including anemia, blood dyscrasias, bone marrow depression, leukopenia, and thrombocytopenia. Bone marrow depression may increase the risk of serious infections and bleeding.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of sodium iodide I 131 states that concurrent use with bone marrow depressants may enhance the depression of the hematopoetic system caused by large doses of sodium iodide I 131.(1) Sodium iodide I 131 causes a dose-dependent bone marrow suppression, including neutropenia or thrombocytopenia, in the 3 to 5 weeks following administration. Patients may be at increased risk of infections or bleeding during this time. Monitor complete blood counts within one month of therapy. If results indicate leukopenia or thrombocytopenia, dosimetry should be used to determine a safe sodium iodide I 131 activity.(1)

DISCUSSION: Hematologic disorders including death have been reported with sodium iodide I 131. The most common hematologic disorders reported include anemia, blood dyscrasias, bone marrow depression, leukopenia, and thrombocytopenia.(1)

Selected Myelosuppressive Agents/Clozapine

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

MECHANISM OF ACTION: Clozapine and other myelosuppressive agents may be associated with neutropenia or agranulocytosis.(2)

CLINICAL EFFECTS: Moderate neutropenia, even if due to combination therapy, may require abrupt discontinuation of clozapine resulting in decompensation of the patient's psychiatric disorder (e.g. schizophrenia). The disease treated by the myelosuppressive agent may be compromised if myelosuppression requires dose reduction, delay, or discontinuation of the myelosuppressive agent. Undetected severe neutropenia or agranulocytosis may be fatal.

PREDISPOSING FACTORS: Low white blood counts prior to initiation of the myelosuppressive agent may increase risk for clinically significant neutropenia.

PATIENT MANAGEMENT: If a patient stabilized on clozapine therapy requires treatment with a myelosuppressive agent, the clozapine prescriber should consult with prescriber of the myelosuppressive agent (e.g. oncologist) to discuss treatment and monitoring options.(2) More frequent absolute neutrophil count (ANC) monitoring or treatment alternatives secondary to neutropenic episodes may need to be considered. The U.S. Food and Drug Administration (FDA) recommends that prescribers monitor patients' ANC according to the monitoring frequencies described in the prescribing information. Severe neutropenia remains a serious, potentially fatal risk that is greatest in the first several months of clozapine treatment. ANC monitoring can help identify neutropenia early to allow for timely intervention.(1-2) Australia, Canada, and U.K.: Clozapine is only available through a restricted distribution system which requires documentation of the ANC prior to dispensing. For most clozapine patients, clozapine treatment must be interrupted for a suspected clozapine-induced ANC < 1000 cells/microliter. For patients with benign ethnic neutropenia (BEN), treatment must be interrupted for suspected clozapine-induced neutropenia < 500 cells/microliter.(2)

DISCUSSION: Concurrent use of clozapine and selected myelosuppressive agents may require more frequent ANC monitoring or consideration of treatment alternatives secondary to neutropenic episodes. Agents linked to this interaction generally have > 5% risk for neutropenia and/or warnings describing risk for myelosuppression in manufacturer prescribing information.(3-26)

Selected Myelosuppressive Agents/Deferiprone

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

MECHANISM OF ACTION: Concurrent use of deferiprone with other drugs known to be associated with neutropenia or agranulocytosis may increase the frequency or risk for severe toxicity.(1)

CLINICAL EFFECTS: Concurrent use of deferiprone and myelosuppressive agents may result in severe neutropenia or agranulocytosis, which may be fatal.

PREDISPOSING FACTORS: Agranulocytosis may be less common in patients receiving deferiprone for thalassemia, and more common in patients treated for other systemic iron overload conditions (e.g. myelodysplastic syndromes, sickle cell disease).(2,3) Inadequate monitoring appears to increase the risk for severe outcomes. Manufacturer post market surveillance found that in all fatal cases of agranulocytosis reported between 1999 and 2005, data on weekly white blood count (WBC) monitoring was missing. In three fatal cases, deferiprone was continued for two to seven days after the detection of neutropenia or agranulocytosis.(2)

PATIENT MANAGEMENT: If possible, discontinue one of the drugs associated with risk for neutropenia or agranulocytosis. If alternative therapy is not available, documentation and adherence to the deferiprone monitoring protocol is essential. Baseline absolute neutrophil count (ANC) must be at least 1,500/uL prior to starting deferiprone. Monitor ANC weekly during therapy. If infection develops, interrupt deferiprone therapy and monitor ANC more frequently. If ANC is less than 1,500/uL but greater than 500/uL, discontinue deferiprone and any other drugs possibly associated with neutropenia. Initiate ANC and platelet counts daily until recovery (i.e. ANC at least 1,500/uL). If ANC is less than 500/uL, discontinue deferiprone, evaluate patient and hospitalize if appropriate. Do not resume deferiprone unless potential benefits outweigh potential risks.(1)

DISCUSSION: Drugs linked to this monograph have an FDA Boxed Warning for risk of neutropenia, agranulocytosis, or pancytopenia, or have > 5% risk for neutropenia and/or warnings describing risk for myelosuppression in manufacturer prescribing information.(1-25) In pooled clinical studies submitted to the FDA, 6.1% of deferiprone patients met criteria for neutropenia and 1.7% of patients developed agranulocytosis.(1) The time to onset of agranulocytosis was highly variable with a range of 65 days to 9.2 years (median, 161 days).(3)

Selected Myelosuppressive Agents/Dipyrone

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

MECHANISM OF ACTION: Concurrent use of dipyrone with other drugs known to be associated with neutropenia or agranulocytosis may increase the frequency or risk for severe toxicity.(1-29)

CLINICAL EFFECTS: Concurrent use of dipyrone with agents that cause bone marrow depression, including myelosuppressives, may result in an enhanced risk of hematologic disorders, including anemia, blood dyscrasias, bone marrow depression, leukopenia, and thrombocytopenia. Bone marrow depression may increase the risk of serious infections and bleeding. Undetected severe neutropenia or agranulocytosis may be fatal.(1-29)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Concurrent use of dipyrone and myelosuppressive agents should be avoided. The European Medicines Agency states dipyrone is contraindicated in patients with a prior medical history of dipyrone-induced agranulocytosis (or from other pyrazolones/pyrazolidines), impaired bone marrow function or diseases of the hematopoietic system.(3) International labeling for dipyrone and methotrexate state that co-administration may increase the hematotoxicity of methotrexate, especially in elderly patients, and therefore should be avoided.(1-2) The European Medicines Agency advises if agranulocytosis is suspected with dipyrone, a complete blood count (including differential blood count) should be performed immediately, and treatment must be stopped while waiting for the results. If confirmed, treatment must not be reintroduced.(1-3)

DISCUSSION: A retrospective cohort study analyzed new users of dipyrone (n=444,972), non-steroidal anti-inflammatory drugs (n=3,814,367) which served as a reference cohort, and opioids-paracetamol (n=3,129,221) which was the negative control. During continuous treatment over a median of 37-40 days, 26 cases of hospitalized agranulocytosis occurred. With the assumption that agranulocytosis onset was 7 days prior to admission, the hazard ratio of agranulocytosis associated with dipyrone was 4.40 [0.90-21.57] compared to NSAIDs and 2.45 [0.68-8.83] compared to opioid-paracetamol. HR of neutropenia from dipyrone was 2.98 [1.57-5.65] compared to NSAIDs and not statistically significant compared to opioids-paracetamol. In a sensitivity analysis assuming that the onset of agranulocytosis was the date of hospitalization, the HR of dipyrone-induced agranulocytosis was 7.20 [95% confidence interval: 1.92-26.99] compared to NSAIDs and 3.31 [1.17-9.34] compared to opioids-paracetamol. Agranulocytosis was very rare but more than 4 times more common with dipyrone than other analgesics.(4) In a review of 1,448 reports of agranulocytosis attributed to dipyrone, patients with fatal outcomes were older and more often had also received methotrexate compared to those with non-fatal outcomes (odds ratio: 5.18; 95% confidence interval: 3.06-8.78).(5) Agents linked to this interaction generally have > 5% risk for neutropenia and/or warnings describing risk for myelosuppression in manufacturer prescribing information.(2,6-26)

Selected Nephrotoxic Agents/Foscarnet

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

MECHANISM OF ACTION: Foscarnet is nephrotoxic. Concurrent administration of other nephrotoxic agents may result in additive or synergistic effects on renal function.(1) Concurrent intravenous pentamidine may also result in hypocalcemia.(1)

CLINICAL EFFECTS: Concurrent use of foscarnet with nephrotoxic agents such as acyclovir, adefovir, intravenous aminoglycosides, amphotericin B, cyclosporine, methotrexate, non-steroidal anti-inflammatory agents, intravenous pentamidine, tacrolimus, tenofovir, vancomycin and voclosporin may result in renal toxicity.(1) Other nephrotoxic agents include capreomycin, cisplatin, gallium nitrate, high-dose methotrexate, and streptozocin.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of foscarnet state that concurrent administration of potentially nephrotoxic agents such as acyclovir, intravenous aminoglycosides, amphotericin B, cyclosporine, methotrexate, tacrolimus, and intravenous pentamidine should be avoided.(1) Other nephrotoxic agents include adefovir, capreomycin, cisplatin, gallium nitrate, high-dose methotrexate, non-steroidal anti-inflammatory agents, streptozocin, tenofovir, vancomycin and voclosporin. If concurrent therapy is warranted, monitor renal function closely. In patients receiving concurrent foscarnet and pentamidine, also monitor serum calcium levels and instruct patients to report severe muscle spasms, mental/mood changes, and/or seizures.(1)

DISCUSSION: The safety of foscarnet has not been studied in patients receiving other known potentially nephrotoxic agents. Renal impairment is the major toxicity of foscarnet.(1)

Selected Nephrotoxic Agents/Inotersen

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

MECHANISM OF ACTION: Inotersen can cause glomerulonephritis and renal toxicity. Concurrent administration of other nephrotoxic agents may result in additive or synergistic effects on renal function.(1)

CLINICAL EFFECTS: Concurrent use of inotersen with nephrotoxic agents such as acyclovir, adefovir, intravenous aminoglycosides, amphotericin B, cyclosporine, methotrexate, non-steroidal anti-inflammatory agents, intravenous pentamidine, tacrolimus, tenofovir, vancomycin and voclosporin may result in renal toxicity.(1) Other nephrotoxic agents include capreomycin, cisplatin, gallium nitrate, high-dose methotrexate, and streptozocin.

PREDISPOSING FACTORS: Patients with pre-existing renal impairment.

PATIENT MANAGEMENT: The US manufacturer of inotersen state that caution should be used when administered concurrently with potentially nephrotoxic agents or agents that impair renal function.(1) If concurrent therapy is warranted, monitor renal function closely.(1)

DISCUSSION: The safety of inotersen has not been studied in patients receiving other known potentially nephrotoxic agents. Inotersen is only available through a Tegsedi REMS program because of the risk of glomerulonephritis and severe thrombocytopenia.(1)

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

Amphotericin/Gentamicin, Amikacin, Tobramycin

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

MECHANISM OF ACTION: The ototoxic or nephrotoxic effects of gentamicin, amikacin, or tobramycin may be additive with those of amphotericin.

CLINICAL EFFECTS: The concurrent administration of gentamicin, amikacin, or tobramycin with amphotericin may result in additive ototoxic or nephrotoxic effects.(1)

PREDISPOSING FACTORS: Preexisting renal impairment, sepsis, extended duration of aminoglycoside therapy, greater than one aminoglycoside dose per day, or concomitant use of additional nephrotoxic agents such as iodinated contrast media or vancomycin appear to increase the risk for nephrotoxicity and ototoxicity.(1-6). Patients carrying certain variants in the MT-RNR1 gene (m.1555A>G, m.1095T>C, and m.1494C>T) are at increased risk of developing ototoxicity. An additional risk factor includes patients with a maternal relative known to have a clinically relevant MT-RNR1 variant. The risk of ototoxicity can occur at standard recommended doses of aminoglycosides.(7)

PATIENT MANAGEMENT: The Australian manufacturer of gentamicin, amikacin, and tobramycin state that the concurrent use of gentamicin, amikacin, or tobramycin and amphotericin should be avoided.(1,4,5)

DISCUSSION: The Australian and U.K. manufacturers of gentamicin, amikacin, and tobramycin state that since the ototoxic or nephrotoxic effects of gentamicin, amikacin, or tobramycin may be additive, avoid concurrent or sequential use of other neurotoxic and/or nephrotoxic agents including amphotericin.(1,3,4,5)

Selected Nephrotoxic Agents/Adefovir

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

MECHANISM OF ACTION: Recommended doses of adefovir have been associated with delayed nephrotoxicity.(1-4) Concurrent administration of other nephrotoxic agents may result in additive or synergistic effects on renal function.(1)

CLINICAL EFFECTS: Concurrent use of adefovir with nephrotoxic agents such as intravenous aminoglycosides, amphotericin B, cyclosporine, tacrolimus,tenofovir, vancomycin, voclosporin and non-steroidal anti-inflammatory agents may result in renal toxicity.(1) Other nephrotoxic agents include capreomycin, cisplatin, gallium nitrate, high-dose methotrexate, intravenous pentamidine, and streptozocin.

PREDISPOSING FACTORS: Patients with pre-existing renal impairment(1,2) or receiving multiple nephrotoxic agents appear to be at greater risk for nephrotoxicity.

PATIENT MANAGEMENT: Evaluate renal function prior to initiation of concurrent therapy and continue renal function monitoring during therapy. Dose adjustments may be required for impaired renal function. Weigh the risks and benefits of concurrent therapy in patients with treatment-emergent nephrotoxicity.

DISCUSSION: Because of the known risks for adefovir nephrotoxicity, particularly at higher than recommended doses, the safety of adefovir has not been studied in patients receiving other known potentially nephrotoxic agents.

Selected Nephrotoxic Agents/Immune Globulin Iv (IGIV)

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

MECHANISM OF ACTION: Immune Globulin Intravenous (IGIV) products, particularly those containing sucrose, can cause renal dysfunction, acute renal failure, osmotic nephrosis, and/or death. Concurrent administration of other nephrotoxic agents may result in additive or synergistic effects on renal function.(1-4)

CLINICAL EFFECTS: Concurrent use of Immune Globulin Intravenous (IGIV) products with nephrotoxic agents such as adefovir, intravenous aminoglycosides, amphotericin B, non-steroidal anti-inflammatory agents, tenofovir, and vancomycin may result in renal toxicity.(1-4) Other nephrotoxic agents include capreomycin, gallium nitrate, and streptozocin.

PREDISPOSING FACTORS: Patients at risk of acute renal failure include those with any degree of pre-existing renal insufficiency, diabetes mellitus, advanced age (above 65 years of age), volume depletion, sepsis, paraproteinemia, or receiving known nephrotoxic drugs.(1-4) Renal dysfunction and acute renal failure occur more commonly in patients receiving IGIV products containing sucrose.(3-4)

PATIENT MANAGEMENT: For patients at risk of renal dysfunction or renal failure, the US manufacturers of Immune Globulin Intravenous (IGIV) products recommends administration at the minimum dose and infusion rate practicable; ensure adequate hydration in patients before administration; and monitor renal function and urine output with assessment of blood urea nitrogen (BUN) and serum creatinine before initial infusion and at regular intervals during therapy.(1-3) Concurrent administration of potentially nephrotoxic agents should be avoided.(1) Review prescribing information for IGIV product to be administered for sucrose content. If concurrent therapy is warranted, monitor renal function closely. In high risk patients, consider selecting an IGIV product that does not contain sucrose.

DISCUSSION: The safety of Immune Globulin Intravenous (IGIV) has not been studied in patients receiving other known potentially nephrotoxic agents. Renal impairment is a major toxicity of IGIV products.(1-3) A review of the FDA renal adverse events (RAEs) (i.e. acute renal failure or insufficiency) from June 1985 to November 1998 identified 120 reports worldwide associated with IGIV administration. In the US, the FDA received 88 reports of cases with clinical and/or laboratory findings consistent with RAE (i.e. increased serum creatinine, oliguria, and acute renal failure). Patient cases involved a median age of 60.5 years and 55% were male. Of the 54 patients who developed acute renal failure, 65% were greater than 65 years, 56% had diabetes, and 26% had prior renal insufficiency; 59% had one, 35% had two, and 6% had three of these conditions. Upon review of the IGIV product received, 90% of cases received sucrose-containing IGIV products with the remaining patients receiving either maltose- or glucose-containing products. Approximately 40% of affected patients required dialysis and RAE may have contributed to death in 15% of patients.(4)

Selected Nephrotoxic Agents/Tenofovir

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

MECHANISM OF ACTION: Tenofovir and other nephrotoxic agents may result in additive or synergistic effects on renal function and increase nephrotoxicity risk.(1)

CLINICAL EFFECTS: Concurrent use of tenofovir and other nephrotoxic agents may result in renal toxicity and acute renal failure.(1) Reports of acute renal failure and Fanconi syndrome have been reported with tenofovir use.(2,3) However, this has been reported in 3 case reports and the renal failure may have been complicated by other pre-existing conditions.(2)

PREDISPOSING FACTORS: Pre-existing renal dysfunction, long duration of use, low body weight, concomitant use of drugs that may increase tenofovir levels may increase the risk of nephrotoxicity.(1)

PATIENT MANAGEMENT: The US prescribing information for tenofovir recommends avoiding concurrent or recent use of a nephrotoxic agent.(3) Evaluate renal function prior to initiation of concurrent therapy and continue renal function monitoring during therapy. Dose adjustments may be required for impaired renal function. Tenofovir should be avoided with high-dose or multiple NSAIDs. Alternatives to NSAIDs should be considered in patients at risk for renal dysfunction.(3) Patients receiving concurrent NSAIDs with tenofovir should be monitored for possible renal toxicity.(1,2) The dosing interval should be adjusted in patients with a baseline creatinine clearance of less than 50 ml/min.(1-3)

DISCUSSION: From March 18, 2003 to December 1, 2005, Health Canada received 10 reports of nephrotoxic reactions with tenofovir. Three of these occurred following the addition of a NSAID to tenofovir therapy. In the first report, a patient maintained on tenofovir for 29 months developed acute renal failure and acute tubular necrosis requiring dialysis 5 days after beginning indomethacin (100 mg rectally twice daily). In the second report, a patient maintained on tenofovir for 7 months developed acute renal failure and acute tubular necrosis after taking 90 tablets of naproxen (375 mg) over 2 months. The patient died. In the third report, a patient maintained on tenofovir for over a year developed acute renal failure and nephrotic syndrome after 2 months of valdecoxib (20 mg daily) therapy. Symptoms subsided following discontinuation of valdecoxib.(1)

*Hypersensitivity to amphotericin B or any other component in the respective formulation. The manufacturers of conventional amphotericin B and amphotericin B liposomal suggest that use of these drugs can be considered in patients with hypersensitivity if the clinician determines that the benefits of such therapy outweigh the risks.

There are no contraindication contraindications for this drug.

• Hypokalemia
• Hypomagnesemia
• Systemic mastocytosis

• Kidney disease with reduction in glomerular filtration rate (GFr)

The most commonly reported adverse effects reported with conventional amphotericin B include fever (sometimes accompanied by chills), malaise, weight loss, hypotension, tachypnea, anorexia, nausea, vomiting, diarrhea, dyspepsia, cramping epigastric pain, normochromic, normocytic anemia, pain at the injection site (with or without phlebitis or thrombophlebitis), generalized pain (including muscle/joint pains), headache, and decreased renal function and renal function abnormalities (e.g., azotemia, hypokalemia, hyposthenuria, renal tubular acidosis, nephrocalcinosis).

In a study of amphotericin B liposomal as empiric therapy in adults, the only adverse effects reported more frequently than with conventional IV amphotericin B and in >=20% of patients were diarrhea and rash. Amphotericin B liposomal is associated with a lower overall incidence of chills, changes in blood pressure, tachycardia, hypoxia, hypokalemia, and various adverse effects related to renal toxicity than the conventional formulation of the drug.

More Frequent

• Chills
• Dyspnea
• Fever
• Hypokalemia

Less Frequent

• Back pain
• Chest pain
• Hypertension
• Hypotension
• Increased alanine transaminase
• Increased aspartate transaminase
• Jaundice
• Skin rash
• Urine discoloration

Rare or Very Rare

• Acute renal failure
• Agranulocytosis
• Anaphylaxis
• Angioedema
• Hemorrhagic cystitis
• Hypoventilation
• Pulmonary edema
• Rhabdomyolysis

More Frequent

• Acute abdominal pain
• Diarrhea
• Headache disorder
• Insomnia
• Nausea
• Vomiting

Less Frequent

• Acute cognitive impairment
• Cough
• Hematuria
• Peripheral edema

Rare or Very Rare

• Abnormal vaginal bleeding
• Dysuria
• Erythema
• Kidney disease with reduction in glomerular filtration rate (GFr)
• Urinary incontinence
• Urticaria

No enhanced messaging available.

Although safety and efficacy of conventional IV amphotericin B in pediatric patients have not been established through adequate and well-controlled studies, the drug has been used effectively to treat systemic fungal infections in pediatric patients without unusual adverse effects. The manufacturers state that the lowest effective dosage of the drug should be employed whenever conventional IV amphotericin B is used in pediatric patients.

IV amphotericin B liposomal has been administered to pediatric patients 1 month to 16 years of age without any unusual adverse effects. In clinical studies of 302 pediatric patients, there were no differences in efficacy or safety of IV amphotericin B liposomal when compared to adult patients. In a large, double-blind study comparing the safety and efficacy of amphotericin B liposomal and conventional IV amphotericin B, the incidence of chills, vomiting, hypokalemia, or hypertension in patients 16 years of age or younger ranged from 10-37% in those receiving amphotericin B liposomal and from 21-68% in those receiving the conventional formulation of the drug.

Safe use of amphotericin B during pregnancy has not been established. Conventional IV amphotericin B has been used to treat systemic fungal infections or visceral leishmaniasis in a limited number of pregnant women without obvious adverse effects to the fetus. While reproduction studies in rats and rabbits using conventional amphotericin B or amphotericin B liposomal have not revealed evidence of harm to the fetus, rabbits receiving amphotericin B liposomal dosages equivalent to 0.5-2 times the usual human dosage experienced a higher rate of spontaneous abortions than the control group. However, animal reproduction studies are not always predictive of human response. There are no adequate or controlled studies to date using any amphotericin B formulation in pregnant women, and these drugs should be used during pregnancy only when clearly needed.

It is not known whether amphotericin B is distributed into human milk. Because many drugs are distributed into human milk and because of the potential for serious adverse reactions to amphotericin B in nursing infants if it were distributed, a decision should be made whether to discontinue nursing or the drug, taking into account the importance of the drug to the woman.

Although clinical experience to date indicates that dosage modification is unnecessary when amphotericin B liposomal is used in geriatric patients, the manufacturer recommends that these patients be carefully monitored while receiving the drug.

While safety and efficacy of conventional IV amphotericin B and amphotericin B liposomal have not been studied specifically in geriatric patients, no unusual age-related adverse effects have been reported when the drugs were used in patients 65 years of age or older. Although dosage modifications are usually unnecessary, carefully monitor during treatment.