Eplerenone (eplerenone)

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

Eplerenone/Strong Cyp3a4 Inhibitors; Protease Inhibitors

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: Strong inhibitors of CYP3A4 and protease inhibitors may inhibit the metabolism of eplerenone.(1-3)

CLINICAL EFFECTS: Concurrent use of eplerenone with a strong inhibitor of CYP3A4 or a protease inhibitor may result in 5-fold increases in eplerenone concentrations and toxicity (e.g. hyperkalemia, hypotension).(1-3)

PREDISPOSING FACTORS: Severe renal disease increases the risk for hyperkalemia.

PATIENT MANAGEMENT: The manufacturer of eplerenone states that the concurrent use of strong CYP3A4 inhibitors is contraindicated.(1) The US Department of Health and Human Services HIV guidelines state that protease inhibitors are contraindicated with eplerenone.(3) The US manufacturer of itraconazole states that concurrent use of eplerenone is contraindicated during and two weeks after itraconazole treatment.(4) The starting dose of eplerenone for hypertension should be reduced to 25 mg in patients receiving moderate CYP3A4 inhibitors.(1) In all patients taking eplerenone who start taking a moderate CYP3A4 inhibitor, check serum potassium and creatinine levels after 3-7 days of concurrent therapy.(1)

DISCUSSION: Ketoconazole (200 mg BID) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of eplerenone (100 mg) by 1.7-fold and 5.4-fold, respectively.(1) The concurrent use of eplerenone with less potent CYP3A4 inhibitors (erythromycin 500 mg BID, fluconazole 200 mg daily, saquinavir 1200 mg TID, and verapamil 240 mg daily) increased the Cmax of eplerenone by 1.4-fold to 1.6-fold and the AUC of eplerenone by 2.0-fold and 2.9-fold.(1) Strong inhibitors of CYP3A4 and protease inhibitors linked to this monograph include: adagrasib, amprenavir, atazanavir, boceprevir, ceritinib, clarithromycin, cobicistat, darunavir, ensitrelvir, fosamprenavir, idelalisib, indinavir, itraconazole, josamycin, ketoconazole, lonafarnib, lopinavir, mibefradil, mifepristone, nefazodone, nelfinavir, nirmatrelvir/ritonavir, paritaprevir, posaconazole, relacorilant, ribociclib, saquinavir, telaprevir, telithromycin, tipranavir, troleandomycin, tucatinib, and voriconazole.(1,2)

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

Aldosterone Receptor Antagonists/Potassium Sparing Diuretics

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

MECHANISM OF ACTION: Aldosterone receptor antagonists increase serum potassium levels, as do potassium-sparing diuretics.(1-3)

CLINICAL EFFECTS: Concurrent use of aldosterone receptor antagonists with a potassium sparing diuretic may result in hyperkalemia.(1-3)

PREDISPOSING FACTORS: Renal impairment

PATIENT MANAGEMENT: The manufacturer of eplerenone states that the use of eplerenone for the treatment of hypertension in patients receiving potassium-sparing diuretics is contraindicated.(1) The US manufacturer of spironolactone states that spironolactone should not be used with potassium-sparing diuretics.(2) The US manufacturer of finerenone states that more frequent monitoring of potassium may be necessary in patients on concomitant medications that impair potassium excretion or increase serum potassium levels.(3)

DISCUSSION: The one of the main risks of aldosterone receptor antagonist therapy is hyperkalemia. The risk of hyperkalemia can be reduced by avoiding potassium sparing diuretics during therapy.(1-3)

Aldosterone Receptor Antagonists/Trimethoprim

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

MECHANISM OF ACTION: Eplerenone, finerenone, spironolactone, and trimethoprim have all been proven to increase serum potassium levels.(1-7) The increase is achieved by reduction in potassium elimination by trimethoprim(4,5) and inhibition of aldosterone by eplerenone, finerenone, and spironolactone.(2,3,8) The use of these medications in combination can have an additive effect on serum potassium resulting in potentially dangerous levels.(9)

CLINICAL EFFECTS: Concurrent use of trimethoprim and aldosterone antagonists may result in increased serum potassium levels(9) and risk of sudden death.(10)

PREDISPOSING FACTORS: Interaction risk appears to be greater in patients with renal insufficiency, heart failure, when receiving other drugs associated with hyperkalemia risk (e.g. ACE Inhibitors, non-steroidal antiinflammatory agents(NSAIDs), angiotensin II receptor antagonists), and/or in older patients.(1,2,3,6,9,10)

PATIENT MANAGEMENT: Alternative antibiotic therapy should be considered for patients who have renal impairment, heart failure, or take other meds associated with hyperkalemia risk.(1,2,9,10) Patients using trimethoprim and an aldosterone antagonist concurrently should have their serum potassium monitored at baseline and during treatment. Peak potassium increase is delayed and generally occurs after 4 or more days of therapy.(6)

DISCUSSION: A nested case-control study of elderly patients chronically treated with spironolactone evaluated hospital admissions due to hyperkalemia within 14 days of receiving a prescription for SMX-TMP, amoxicillin, norfloxacin, or nitrofurantion. 248 patients were identified. Two thirds of the patients with hyperkalemia on admission had received SMX-TMP, a 12-fold increased risk compared to patients receiving amoxicillin or norfloxacin.(9) A nested case-control study of elderly patients chronically treated with spironolactone evaluated sudden death within 14 days of receiving a prescription for SMX-TMP, amoxicillin, ciprofloxacin, norfloxacin, or nitrofurantion. 328 patients were identified and matched to up to 4 case controls. Compared with amoxicillin, use of SMX-TMP was associated with a more than 2-fold (2.46 adjusted OR) increased risk of death.(10)

Baxdrostat; Potassium-Spar Diuretics/Cyclosporine;Tacrolimus

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

MECHANISM OF ACTION: Concurrent use of cyclosporine(1) or tacrolimus(2) with baxdrostat(3) or a potassium-sparing diuretic may result in additive or synergistic effects on potassium levels.

CLINICAL EFFECTS: Concurrent use of cyclosporine(1) or tacrolimus(2) with baxdrostat(3) or a potassium-sparing diuretic may result in severe hyperkalemia.

PREDISPOSING FACTORS: Renal impairment increases the risk for hyperkalemia.

PATIENT MANAGEMENT: The US manufacturers of cyclosporine(1) and tacrolimus(2) state that potassium-sparing diuretics should not be used during therapy with these agents.

DISCUSSION: Hyperkalemia has been reported with cyclosporine, therefore, the US manufacturer states that potassium-sparing diuretics should not be used with cyclosporine.(1) In tacrolimus clinical trials, mild to severe hyperkalemia was reported in 31% of kidney transplant patients, 45% of US liver transplant patients, and 13% of European liver transplant patients. The manufacturer of tacrolimus states that potassium levels should be closely monitored in all patients maintained on tacrolimus and that potassium-sparing diuretics should be avoided during tacrolimus therapy.(2)

Diuretics/Sodium Phosphate Bowel Cleanser

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

MECHANISM OF ACTION: Bowel cleansing with sodium phosphate causes dehydration, decreased intravascular volume and hyperphosphatemia, which increases phosphate levels in the renal tubules. Abnormally high levels of calcium and phosphate in the renal tubules may precipitate out, resulting in renal injury.(1)

CLINICAL EFFECTS: Use of sodium phosphate for bowel cleansing in patients maintained on diuretics may increase the risk of acute phosphate nephropathy, which is an acute kidney injury associated with deposits of calcium phosphate crystal in the renal tubules that may result in permanent renal function impairment. Acute phosphate nephropathy presents as acute kidney injury with minimal proteinuria and a bland urine sediment.(2) Use of oral sodium phosphate products at laxative doses has not been associated with acute kidney injury.(3)

PREDISPOSING FACTORS: Patients who may be at an increased risk of acute phosphate nephropathy include those who are over age 55; are hypovolemic or have decreased intravascular volume; have baseline kidney disease, bowel obstruction, or active colitis; and who are using medications that affect renal perfusion or function (such as diuretics, angiotensin converting enzyme (ACE) inhibitors, angiotension receptor blockers (ARBs) and possibly nonsteroidal anti-inflammatory drugs (NSAIDs).(2)

PATIENT MANAGEMENT: If possible, use an alternative agent for bowel cleansing.(1) Use sodium phosphate products with caution in patients taking medications that affect kidney function or perfusion, such as diuretics. Obtain baseline and post-procedure labs (electrolytes, calcium, phosphate, BUN, creatinine, and [in smaller, frail individuals] glomerular filtration rate). Instruct patients to drink sufficient quantities of clear fluids before, during, and after bowel cleansing and to avoid other laxatives that contain sodium phosphate. Consider hospitalization and intravenous hydration during bowel cleansing to support frail patients who may be unable to drink an appropriate volume of fluid or who may be without assistance at home.(2) Use of an electrolyte solution for rehydration may decrease the risk of acute phosphate nephropathy.(4,5)

DISCUSSION: Since May 2006, the FDA has received 20 reports of acute phosphate nephropathy associated with the use of Osmo Prep. Concomitant medications included ACE inhibitors or ARBs (11), diuretics (6), and NSAIDs (4).(2) In a retrospective review of colonoscopy patients, simultaneous use of ACE inhibitors or ARBs significantly increased the risk of acute kidney injury from oral sodium phosphate. Diuretic use was also a risk factor.(6) In a case series study of 21 cases of acute phosphate nephropathy in patients who had used oral sodium phosphate, 14 patients received an ACE inhibitor or ARB, 4 used a diuretic, and 3 used an NSAID.(7) Cases have also been reported with rectal products.(8)

Eplerenone/Potassium Supplements

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

MECHANISM OF ACTION: Eplerenone increases serum potassium levels.(1)

CLINICAL EFFECTS: Concurrent use of eplerenone with a potassium supplement may result in hyperkalemia.(1)

PREDISPOSING FACTORS: Renal impairment.

PATIENT MANAGEMENT: The manufacturer of eplerenone states that the use of eplerenone for the treatment of hypertension in patients receiving potassium supplements is contraindicated.(1)

DISCUSSION: The main risk of eplerenone therapy is hyperkalemia. The risk of hyperkalemia can be reduced by avoiding potassium supplements during eplerenone therapy.(1)

Eplerenone/Selected Moderate Cyp3a4 Inhibitors

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

MECHANISM OF ACTION: Moderate inhibitors of CYP3A4 may inhibit the metabolism of eplerenone.(1)

CLINICAL EFFECTS: Concurrent use of moderate inhibitors of CYP3A4 may result in a 2-fold increase in eplerenone concentration and toxicity (e.g. hyperkalemia, hypotension).(1)

PREDISPOSING FACTORS: Severe renal disease increases the risk for hyperkalemia.

PATIENT MANAGEMENT: The starting dose of eplerenone for hypertension should be reduced to 25 mg in patients receiving moderate CYP3A4 inhibitors. For inadequate blood pressure response, dosing may be increased to a maximum of 25 mg twice daily. Do not exceed 25 mg once daily in post-MI CHF patients receiving a moderate CYP3A4 inhibitor.(1) In all patients taking eplerenone who start taking a moderate CYP3A4 inhibitor, check serum potassium and creatinine levels after 3-7 days of concurrent therapy.(1)

DISCUSSION: Ketoconazole (200 mg BID) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of eplerenone (100 mg) by 1.7-fold and 5.4-fold, respectively.(1) The concurrent use of eplerenone with less potent CYP3A4 inhibitors (erythromycin 500 mg BID, fluconazole 200 mg daily, saquinavir 1200 mg TID, and verapamil 240 mg daily) increased the Cmax of eplerenone by 1.4-fold to 1.6-fold and the AUC of eplerenone by 2.0-fold and 2.9-fold.(1) Moderate inhibitors of CYP3A4 include: aprepitant, avacopan, berotralstat, clofazimine, conivaptan, crizotinib, diltiazem, duvelisib, erythromycin, fedratinib, fluconazole, fluvoxamine, fosnetupitant, imatinib, isavuconazonium, lefamulin, lenacapavir, letermovir, netupitant, nilotinib, nirogacestat, rilzabrutinib, schisandra, stiripentol, treosulfan, and verapamil.(1-3)

Selected Sensitive Cyp3a4 Substrates/Voxelotor

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

MECHANISM OF ACTION: Voxelotor is an inhibitor of CYP3A4 and may decrease the metabolism of drugs metabolized by the CYP3A4 enzyme.

CLINICAL EFFECTS: Concurrent use of voxelotor may lead to increased serum levels and adverse effects of drugs sensitive to inhibition of the CYP3A4 pathway.(1)

PREDISPOSING FACTORS: A greater risk for serious adverse events would be expected from drugs having a narrow therapeutic window.

PATIENT MANAGEMENT: The manufacturer of voxelotor states that co-administration of sensitive CYP3A4 substrates with a narrow therapeutic index should be avoided. If concomitant use is unavoidable, consider dose reduction of the sensitive substrate.(1)

DISCUSSION: In a study, voxelotor increased the AUC of a single dose of midazolam by 1.6-fold. After multiple doses of midazolam, a 2.5-fold increase in AUC is predicted.(1) Sensitive CYP3A4 substrates with a narrow therapeutic index linked to this monograph include: avanafil, conivaptan, cyclosporine, dihydroergotamine, eplerenone, ergotamine, everolimus, felodipine, fentanyl, lomitapide, lovastatin, methylergonovine, midazolam, nisoldipine, sildenafil, simvastatin, ticagrelor, tolvaptan, triazolam, and vardenafil.(2,3)

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

Agents That Increase Potassium/Baxdrostat

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

MECHANISM OF ACTION: The combination of baxdrostat and agents that increase potassium such as aldosterone receptor antagonists, potassium-sparing diuretics, and potassium supplements can have an additive effect on serum potassium levels.

CLINICAL EFFECTS: Concurrent use of baxdrostat and agents that increase potassium may result in hyperkalemia, which may be severe.

PREDISPOSING FACTORS: More frequent monitoring is recommended for patients at increased risk of hyperkalemia (e.g., patients greater than or equal to 65 years or age, those with diabetes mellitus or chronic kidney disease).(1)

PATIENT MANAGEMENT: The manufacturer of baxdrostat states concurrent use with medications that may increase potassium warrants more frequent monitoring of serum potassium.(1) Assess serum potassium prior to initiation of baxdrostat and monitor periodically during treatment. Correct serum potassium abnormalities prior to initiation of baxdrostat.(1) If hyperkalemia occurs, treat hyperkalemia and consider interrupting or discontinuing baxdrostat. Consider more frequent monitoring of serum potassium in patients who restart baxdrostat after experiencing hyperkalemia. Permanently discontinue baxdrostat if clinically significant hyperkalemia recurs.(1)

DISCUSSION: Baxdrostat may increase potassium. Concurrent use with aldosterone receptor antagonists, potassium-sparing diuretics, and potassium supplements may have additive effects on serum potassium levels, resulting in hyperkalemia. The risk of hyperkalemia can be reduced by monitoring serum potassium more frequently when baxdrostat is administered concomitantly with these agents.

Aldosterone Receptor Antag; Baxdrostat/Nsaids; Salicylates

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

MECHANISM OF ACTION: The exact mechanism is unknown; however, nonsteroidal anti-inflammatory (NSAID) inhibition of prostaglandins may allow baxdrostat, eplerenone, finerenone, or spironolactone-induced nephrotoxicity or hyperkalemia to occur in some patients.(1-4) In some patients, NSAIDs may reduce the diuretic, natriuretic and antihypertensive effects of baxdrostat, eplerenone, finerenone, or spironolactone.(1-4)

CLINICAL EFFECTS: Concurrent use of baxdrostat, eplerenone, finerenone, or spironolactone with NSAIDs may result in renal failure or hyperkalemia. The effects of the diuretic, natriuretic, or antihypertensive effects of baxdrostat, eplerenone, finerenone, or spironolactone may be decreased.(1-4)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: When possible, avoid concurrent therapy with baxdrostat, eplerenone, finerenone, or spironolactone with NSAIDs. If these agents are used concurrently, monitor renal function and serum electrolytes. If decreased renal function or hyperkalemia develops, discontinue both agents. The manufacturer of eplerenone recommends checking serum potassium and serum creatinine within 3-7 days of concurrent therapy with NSAIDs.(1) The manufacturer of spironolactone states concurrent use with NSAIDs may lead to severe hyperkalemia and extreme caution should be used during concurrent therapy.(2)

DISCUSSION: Although acute renal failure and hyperkalemia have only been reported in studies and case reports involving indomethacin, diclofenac, flurbiprofen, and ibuprofen with either triamterene or amiloride, the proposed mechanism suggests that all nonsteroidal anti-inflammatory agents may be capable of this interaction with all potassium-sparing diuretics. Patients receiving diuretics are at an increased risk of NSAID-induced renal failure.

Aldosterone Receptor Antagonists; Baxdrostat/Lithium

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

MECHANISM OF ACTION: Aldosterone receptor antagonists, including eplerenone, finerenone and spironolactone, bind to mineralocorticoid receptors, blocking the action of aldosterone. Baxdrostat inhibits aldosterone synthesis. The subsequent increase in sodium and water excretion may lead to reduced renal clearance of lithium.(1-4)

CLINICAL EFFECTS: Lithium has a narrow therapeutic range. Unintended increases in lithium concentrations may lead to lithium toxicity. Early symptoms of lithium toxicity may include: lethargy, muscle weakness or stiffness, new onset or coarsening of hand tremor, vomiting, diarrhea, confusion, ataxia, blurred vision, tinnitus and nystagmus. Severe toxicity may produce multiple organ dysfunction (e.g. seizures, coma, renal failure, cardiac arrhythmias, cardiovascular collapse) and may be fatal.(5)

PREDISPOSING FACTORS: Risk factors for lithium toxicity include: renal impairment or worsening of existing renal disease, dehydration, low sodium diet, and concomitant use of multiple medications which may impair renal elimination of lithium (e.g. ARBs, ACE Inhibitors, NSAIDs, diuretics).(5) Patients who require higher therapeutic lithium levels to maintain symptom control are particularly susceptible to these factors.

PATIENT MANAGEMENT: Evaluate renal function and most recent lithium levels. If renal function is not stable or if the lithium level is in the high therapeutic range, then consider lowering the lithium dose when an aldosterone antagonist is started, or consider withholding the aldosterone antagonist until renal function is stable. If renal function is stable and baseline lithium concentrations are in the therapeutic range, recheck lithium levels 5 to 7 days after initiation of baxdrostat, eplerenone, finerenone, or spironolactone. Adjust the lithium dose as necessary based on lithium serum levels and patient response. If an interacting drug is discontinued, the lithium level may fall. Monitor lithium concentration and adjust dose if needed.(5) Counsel patient to assure they know signs and symptoms of lithium toxicity and understand the importance of follow-up laboratory testing.

DISCUSSION: Although the magnitude and frequency of this specific diuretic interaction is not clear, manufacturer product information for spironolactone and lithium state that lithium patients should generally not receive diuretics.(2,3) The manufacturer of eplerenone recommends frequent monitoring of lithium levels in patients who receive concomitant therapy.(1)

Diuretics/Zoledronic Acid

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

MECHANISM OF ACTION: Concurrent use of zoledronic acid and a diuretic may have adverse effects on the renal system.(1,2)

CLINICAL EFFECTS: Concurrent use of zoledronic acid and a diuretic may result in renal dysfunction. Deterioration in renal function, acute renal failure requiring dialysis, and death have been reported.(1)

PREDISPOSING FACTORS: The interaction may be more likely in elderly patients, patients who are taking other drugs that impact renal function, patients with pre-existing renal compromise, and patients who are dehydrated.(1)

PATIENT MANAGEMENT: Patients should be adequately hydrated with 500 ml (2 glasses of water) before and after zoledronic acid administration.(1) Creatinine clearance should be monitored before and after therapy and zoledronic acid should not be administered in patients with a creatinine clearance less than 35 ml/min.(1,3)

DISCUSSION: Zoledronic acid has been associated with renal dysfunction, including deterioration in renal function, acute renal failure requiring dialysis, and death. Risk factors include advanced age, concomitant nephrotoxic agents, and dehydration.(1) The FDA has received 16 reports of fatal acute renal failure and 9 reports of renal injury requiring dialysis following the administration of Reclast (zoledronic acid).(3)

K+ Sparing Diuretics/Angiotensin Ii Receptor Blocker (ARB)

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

MECHANISM OF ACTION: Angiotensin II receptor blockers (ARBs) may decrease the renal excretion of potassium.

CLINICAL EFFECTS: Concurrent use of potassium sparing diuretics with an ARB may result in hyperkalemia.

PREDISPOSING FACTORS: Impaired renal function; diabetes mellitus.

PATIENT MANAGEMENT: Monitor serum potassium and adjust the dosage accordingly in patients receiving concurrent therapy with a potassium sparing diuretic and an ARB. In all patients taking eplerenone who start taking an an ARB, check serum potassium and creatinine levels after 3-7 days of concurrent therapy.

DISCUSSION: In a nested case-control study of heart failure patients receiving continuous ACE inhibitor/ARB therapy (n = 1,491,894), the risk of hyperkalemia was significantly associated with spironolactone use (odds ratio (OR) = 13.59; confidence interval (CI) = 11.63-15.88).(20) In a systemic literature review and meta-analysis of 20 randomized controlled studies, it was found that treatment with spironolactone and ACEI/ARB combination therapy compared to ACEI/ARB therapy alone increased the mean serum potassium concentration by 0.19 mEq/L (95% CI, 0.12-0.26 mEq/L).(21) A retrospective cohort study in patients with hypertension, diabetes, and albuminuria between 2008 and 2018 examined the efficacy and safety of mineralocorticoid receptor antagonists eplerenone and spironolactone in combination with ACEI/ARB compared to ACEI/ARB alone. Hyperkalemia was more frequent in combination therapy patients (n=1,282) versus monotherapy (n=5,484) (22.3 vs 10.9 per 100 person-years for combination and monotherapy, respectively; HR = 1.78, 95% CI: 1.42, 2.24).(22) Several studies have indicated that serum potassium levels increase when ACE inhibitors and ARB therapy is initiated and decrease when the drug is lowered. There are case reports of hyperkalemia during concurrent therapy with ARBs and spironolactone and with aliskiren and spironolactone. Based on this data, serum potassium levels should be monitored in patients receiving concomitant ARBs with potassium sparing diuretics.

Potassium Sparing Diuretics/Aliskiren

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

MECHANISM OF ACTION: Aliskiren may decrease the renal excretion of potassium.

CLINICAL EFFECTS: Concurrent use of potassium sparing diuretics with aliskiren may result in hyperkalemia.

PREDISPOSING FACTORS: Impaired renal function; diabetes mellitus.

PATIENT MANAGEMENT: Monitor serum potassium and adjust the dosage accordingly in patients receiving concurrent therapy with a potassium sparing diuretic and aliskiren. In all patients taking eplerenone who start taking aliskiren, check serum potassium and creatinine levels after 3-7 days of concurrent therapy.

DISCUSSION: Several studies have indicated that serum potassium levels increase when ACE inhibitors and ARB therapy is initiated and decrease when the drug is lowered. There are case reports of hyperkalemia during concurrent therapy with ARBs and spironolactone and with aliskiren and spironolactone. Based on this data, serum potassium levels should be monitored in patients receiving concomitant aliskiren with potassium sparing diuretics.

Potassium Sparing Diuretics/Drospirenone

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

MECHANISM OF ACTION: Drospirenone has antimineralocorticoid activity and may cause hyperkalemia. Potassium sparing diuretics may also increase potassium levels.(1)

CLINICAL EFFECTS: Concurrent use of drospirenone and potassium sparing diuretics may result in hyperkalemia.(1)

PREDISPOSING FACTORS: Renal insufficiency, hepatic dysfunction, adrenal insufficiency, and use of potassium supplements, ACE inhibitors, angiotensin II receptor antagonists, heparin, and NSAIDs may increase potassium levels.(1)

PATIENT MANAGEMENT: Patients receiving drospirenone with a potassium sparing diuretic should have their serum potassium level checked during the first treatment cycle.(1)

DISCUSSION: Drospirenone has antimineralocorticoid activity comparable to 25 mg of spironolactone and may result in hyperkalemia. Concurrent use of potassium sparing diuretics may also increase potassium levels.(1)

Potassium Sparing Diuretics/Selected Ace Inhibitors

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

MECHANISM OF ACTION: ACE inhibitors decrease the renal excretion of potassium. MECHANISM OF ACTION: ACE inhibitors may decrease the renal excretion of potassium.

CLINICAL EFFECTS: Concurrent use of potassium sparing diuretics with an ACE inhibitor may result in hyperkalemia. CLINICAL EFFECTS: Concurrent use of potassium sparing diuretics with an ACE inhibitor may result in hyperkalemia.

PREDISPOSING FACTORS: Impaired renal function; diabetes mellitus. PREDISPOSING FACTORS: Impaired renal function; diabetes mellitus.

PATIENT MANAGEMENT: Monitor serum potassium and adjust the dosage accordingly in patients receiving concurrent therapy with a potassium sparing diuretic and an ACE inhibitor. In all patients taking eplerenone who start taking an ACE inhibitor, check serum potassium and creatinine levels after 3-7 days of concurrent therapy. PATIENT MANAGEMENT: Monitor serum potassium and adjust the dosage accordingly in patients receiving concurrent therapy with a potassium sparing diuretic and an ACE inhibitors. In all patients taking eplerenone who start taking an ACE inhibitor, check serum potassium and creatinine levels after 3-7 days of concurrent therapy.

DISCUSSION: In a nested case-control study of heart failure patients receiving continuous ACE inhibitor/ARB therapy (n = 1,491,894), the risk of hyperkalemia was significantly associated with spironolactone use (odds ratio (OR) = 13.59; confidence interval (CI) = 11.63-15.88).(20) In a systemic literature review and meta-analysis of 20 randomized controlled studies, it was found that treatment with spironolactone and ACEI/ARB combination therapy compared to ACEI/ARB therapy alone increased the mean serum potassium concentration by 0.19 mEq/L (95% CI, 0.12-0.26 mEq/L).(21) A retrospective cohort study in patients with hypertension, diabetes, and albuminuria between 2008 and 2018 examined the efficacy and safety of mineralocorticoid receptor antagonists eplerenone and spironolactone in combination with ACEI/ARB compared to ACEI/ARB alone. Hyperkalemia was more frequent in combination therapy patients (n=1,282) versus monotherapy (n=5,484) (22.3 vs 10.9 per 100 person-years for combination and monotherapy, respectively; HR = 1.78, 95% CI: 1.42, 2.24).(22) Several studies have indicated that serum potassium levels increase when ACE inhibitors and ARB therapy is initiated and decrease when the drug is lowered. There are case reports of hyperkalemia during concurrent therapy with ARBs and spironolactone and with aliskiren and spironolactone. Based on this data, serum potassium levels should be monitored in patients receiving concomitant ACE inhibitors with potassium sparing diuretics. Selected ACE inhibitors linked to this monograph include: alacepril, cilazapril, delapril, imidapril, spirapril, temocapril, and zofenopril. DISCUSSION: In a nested case-control study of heart failure patients receiving continuous ACE inhibitor/ARB therapy (n = 1,491,894), the risk of hyperkalemia was significantly associated with concomitant spironolactone use (odds ratio (OR) = 13.59; confidence interval (CI) = 11.63-15.88).(20) In a systemic literature review and meta-analysis of 20 randomized controlled studies, it was found that treatment with spironolactone and ACEI/ARB combination therapy compared to ACEI/ARB therapy alone increased the mean serum potassium concentration by 0.19 mEq/L (95% CI, 0.12-0.26 mEq/L).(21) A retrospective cohort study in patients with hypertension, diabetes, and albuminuria between 2008 and 2018 examined the efficacy and safety of mineralocorticoid receptor antagonists eplerenone and spironolactone in combination with ACEI/ARB compared to ACEI/ARB alone. Hyperkalemia was more frequent in combination therapy patients (n=1,282) versus monotherapy (n=5,484) (22.3 vs 10.9 per 100 person-years for combination and monotherapy, respectively; HR = 1.78, 95% CI: 1.42, 2.24).(22) Several studies have indicated that serum potassium levels increase when ACE inhibitors and ARB therapy is initiated and decrease when the drug is lowered. There are case reports of hyperkalemia during concurrent therapy with ARBs and spironolactone and with aliskiren and spironolactone. Based on this data, serum potassium levels should be monitored in patients receiving concomitant ACE inhibitors with potassium sparing diuretics. Selected ACE inhibitors linked to this monograph include: benazepril, captopril, enalapril, fosinopril, lisinopril, perindopril, quinapril, ramipril, and trandolapril.

Selected Antihypertensives And Vasodilators/Apomorphine

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

MECHANISM OF ACTION: Apomorphine causes dose-dependent decreases in blood pressure. Concurrent use with antihypertensive agents may result in additive effects on blood pressure.(1)

CLINICAL EFFECTS: Concurrent use of antihypertensives and apomorphine may result in orthostatic hypotension with or without dizziness, nausea, or syncope.(1)

PREDISPOSING FACTORS: The risk of orthostatic hypotension may be increased during dose escalation of apomorphine and in patients with renal or hepatic impairment.(1)

PATIENT MANAGEMENT: Patients receiving concurrent therapy should be monitored for hypotension. Counsel patients about the risk of orthostatic hypotension.(1)

DISCUSSION: Healthy volunteers who took sublingual nitroglycerin (0.4 mg) concomitantly with apomorphine experienced a mean largest decrease in supine systolic blood pressure (SBP) of 9.7 mm Hg and in supine diastolic blood pressure (DBP) of 9.3 mm Hg, and a mean largest decrease in standing SBP and DBP of 14.3 mm Hg and 13.5 mm Hg, respectively. The maximum decrease in SBP and DBP was 65 mm Hg and 43 mm Hg, respectively. When apomorphine was taken alone, the mean largest decrease in supine SBP and DBP was 6.1 mm Hg and 7.3 mm Hg, respectively, and in standing SBP and DBP was 6.7 mm Hg and 8.4 mm Hg, respectively.(1)

Selected Antihypertensives/Tizanidine

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

MECHANISM OF ACTION: Tizanidine is an alpha-2 agonist. Concurrent use with antihypertensive agents may result in additive effects on blood pressure.(1)

CLINICAL EFFECTS: Concurrent use of antihypertensives and tizanidine may result in hypotension.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients receiving concurrent therapy should be monitored for hypotension. The risk of hypotension may be decreased by careful titration of tizanidine dosages and monitoring for hypotension prior to dose advancement. Counsel patients about the risk of orthostatic hypotension.(1)

DISCUSSION: Severe hypotension has been reported following the addition of tizanidine to existing lisinopril therapy.(2-4)

Selected Potassium Sparing Diuretics/Moexipril

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

MECHANISM OF ACTION: ACE inhibitors such as moexipril may decrease the renal excretion of potassium.

CLINICAL EFFECTS: Concurrent use of potassium sparing diuretics with an ACE inhibitor such as moexipril may result in hyperkalemia.

PREDISPOSING FACTORS: Impaired renal function; diabetes mellitus.

PATIENT MANAGEMENT: Monitor serum potassium and adjust the dosage accordingly in patients receiving concurrent therapy with a potassium sparing diuretic and an ACE inhibitor such as moexipril. In all patients taking eplerenone who start taking moexipril, check serum potassium and creatinine levels after 3-7 days of concurrent therapy.

DISCUSSION: In a nested case-control study of heart failure patients receiving continuous ACE inhibitor/ARB therapy (n = 1,491,894), the risk of hyperkalemia was significantly associated with spironolactone use (odds ratio (OR) = 13.59; confidence interval (CI) = 11.63-15.88).(20) Several studies have indicated that serum potassium levels increase when ACE inhibitors and ARB therapy is initiated and decrease when the drug is lowered. There are case reports of hyperkalemia during concurrent therapy with ARBs and spironolactone and with aliskiren and spironolactone. Based on this data, serum potassium levels should be monitored in patients receiving concomitant moexipril with potassium sparing diuretics.

Eplerenone is contraindicated in patients with serum potassium concentrations exceeding 5.5 mEq/L at initiation of therapy, in those with creatinine clearance of 30 mL/minute or less, and in those receiving concomitant therapy with potent inhibitors of cytochrome P-450 (CYP) isoenzyme 3A4 (e.g., ketoconazole, itraconazole, nefazodone, troleandomycin, clarithromycin, ritonavir, nelfinavir) or any agent described as a potent CYP3A4 inhibitor in its prescribing information.

In addition, when used for hypertension, the drug is contraindicated in patients with type 2 diabetes mellitus with microalbuminuria; serum creatinine concentrations exceeding 2 or 1.8 mg/dL in males or females, respectively; creatinine clearance less than 50 mL/minute; and in those receiving potassium supplements or potassium-sparing diuretics (e.g., amiloride, spironolactone, triamterene).

• Chronic kidney disease stage 3A (moderate) GFR 45-59 ml/min
• Chronic kidney disease stage 3B (moderate) GFR 30-44 ml/min
• Chronic kidney disease stage 4 (severe) GFR 15-29 ml/min
• Chronic kidney disease stage 5 (failure) GFr<15 ml/min
• Hyperkalemia

There are no severe contraindications for this drug.

• Disease of liver

Adverse effects occurring in 2% or more of patients receiving eplerenone for the management of congestive heart failure following acute MI, but occurring at greater incidence in patients receiving the drug than in those receiving placebo, include hyperkalemia, increased serum creatinine concentrations, urinary tract disorders, adverse CNS effects, and adverse GI effects.

Adverse effects reported in 1% or more of patients receiving eplerenone for the management of hypertension are dizziness, fatigue, flu-like symptoms, cough, diarrhea, abdominal pain, hyperkalemia, decreased serum sodium concentrations, abnormal vaginal bleeding, gynecomastia, hypercholesterolemia, hypertriglyceridemia, mastodynia, or albuminuria.

More Frequent

• Hyperkalemia

Less Frequent

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

Rare or Very Rare

• Acute myocardial infarction
• Angina
• Angioedema

Less Frequent

• Abnormal vaginal bleeding
• Dizziness
• Gynecomastia
• Headache disorder

Rare or Very Rare

• Skin rash

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Safety and efficacy have not been established in children younger than 18 years of age. For information on overall principles and expert recommendations for treatment of hypertension in pediatric patients, see Uses: Hypertension in Pediatric Patients, in the Thiazides General Statement 40:28.20.

Category B. (See Users Guide.)

Eplerenone is distributed into milk in rats; a decision should be made whether to discontinue nursing or the drug, taking into account the importance of the drug to the woman.

No substantial differences in safety and efficacy have been observed in geriatric patients relative to younger adults. Geriatric patients 75 years of age and older with congestive heart failure following an acute MI did not benefit from the addition of eplerenone to standard medical therapy. Because geriatric patients may have decreased renal function (reduced creatinine clearance), the incidence of hyperkalemia may be increased in geriatric patients (65 years of age and older). (See Endocrine, Electrolyte, and Metabolic Effects under Warnings/Precautions: Warnings, in Cautions.)