Drug Interactions between eplerenone and fluconazole

Consumption of grapefruit, grapefruit juice, and supplements that contain grapefruit should be avoided during treatment with eplerenone as they may increase the blood levels and effects of eplerenone. High blood levels of eplerenone can increase the risk of side effects including hyperkalemia (high blood potassium), which in severe cases can lead to kidney failure, muscle paralysis, irregular heart rhythm, and cardiac arrest. You may be more likely to develop hyperkalemia during treatment with eplerenone if you are elderly, dehydrated, or have kidney disease, diabetes, or advanced heart failure. You should seek medical attention if you experience nausea, vomiting, weakness, confusion, tingling of the hands and feet, feelings of heaviness in the legs, a weak pulse, or a slow or irregular heartbeat, as these may be symptoms of hyperkalemia. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

The use of eplerenone is contraindicated in patients with type II diabetes mellitus and microalbuminuria. These patients are at increased risk of developing persistent hyperkalemia, which is the principal adverse effect of eplerenone and can lead to potentially life-threatening cardiac arrhythmias. In a study of such patients treated with a 200 mg/day dose, the frequency of maximum serum potassium levels exceeding 5.5 mEq/L was 33% with eplerenone alone and 38% in combination with enalapril. In other patient populations, the frequency has been reported at 1% for the 200 mg/day dose and 8.7% for the 400 mg/day dose. Careful monitoring of serum potassium levels is necessary in patients treated with eplerenone who are at risk for the development of hyperkalemia, especially during initiation of therapy, after dosage adjustment, and during illness that could alter renal function. In clinical trials, monitoring occurred every 2 weeks for the first 1 to 2 months, then monthly thereafter. Eplerenone should be withdrawn immediately if hyperkalemia develops, and measures should be initiated to lower serum potassium if it exceeds 6.5 mEq/L.

The use of eplerenone is contraindicated in the presence of elevated serum potassium concentrations (> 5.5 mEq/L). Eplerenone is a blocker of aldosterone binding at the mineralocorticoid receptor and can cause hyperkalemia, which may result in life-threatening cardiac arrhythmias. Careful monitoring of serum potassium levels is necessary in patients who are at risk for the development of hyperkalemia (including those receiving concomitant ACE inhibitors or angiotensin II receptor antagonists), especially during initiation of therapy, after dosage adjustment, and during illness that could alter renal function. In clinical trials, monitoring occurred every 2 weeks for the first 1 to 2 months, then monthly thereafter. Eplerenone should be withdrawn immediately if hyperkalemia develops, and measures should be initiated to lower serum potassium if it exceeds 6.5 mEq/L.

The use of fluconazole has been rarely associated with hepatotoxicity. Reversible idiosyncratic hepatitis, cholestasis and fatal fulminant hepatic failure have been reported, the latter occurring primarily in patients with serious underlying medical conditions and taking multiple concomitant medications. Liver function tests should be performed periodically in patients with preexisting hepatic abnormalities, particularly during prolonged therapy. Treatment should be withdrawn if persistent elevations or worsening of liver enzyme levels occur.

The use of eplerenone is contraindicated in patients with renal impairment as defined by serum creatinine above 2.0 mg/dL for males or 1.8 mg/dL for females, or a creatinine clearance (CrCl) below 50 mL/min. These patients are at increased risk of developing persistent hyperkalemia, which is the principal adverse effect of eplerenone and can lead to potentially life-threatening cardiac arrhythmias. The incidence of hyperkalemia increases with decreasing renal function. In clinical studies of eplerenone, serum potassium levels exceeding 5.5 mEq/L were observed in 10.4% of treated patients with baseline calculated CrCl less than 70 mL/min, 5.6% of patients with baseline CrCl 70 to 100 mL/min, and 2.6% of patients with baseline CrCl greater than 100 mL/min. Careful monitoring of serum potassium levels is necessary in patients treated with eplerenone who are at risk for the development of hyperkalemia, especially during initiation of therapy, after dosage adjustment, and during illness that could alter renal function. In clinical trials, monitoring occurred every 2 weeks for the first 1 to 2 months, then monthly thereafter. Eplerenone should be withdrawn immediately if hyperkalemia develops, and measures should be initiated to lower serum potassium if it exceeds 6.5 mEq/L.

Some azole antifungals have been associated with prolongation of the QT interval on the ECG. Rare cases of QT prolongation and torsade de pointes have been reported during postmarketing experience; such reports usually involved seriously ill patients with multiple confounding risk factors, such as structural heart disease, electrolyte abnormalities, and concomitant medications. These drugs should be administered with caution to patients with potentially proarrhythmic conditions, such as congenital/acquired QT prolongation, cardiomyopathy (especially when heart failure is present), sinus bradycardia, and existing symptomatic arrhythmias. Concomitant use with other medications that have potential to increase the risk of cardiotoxicity should be avoided.

Fluconazole is substantially removed by hemodialysis. Plasma levels of fluconazole has been shown to reduce by 50% following 3 hours of dialysis. Fluconazole should be administered after hemodialysis.

Eplerenone is primarily metabolized by the liver. In patients with moderate (Child-Pugh Class B) hepatic impairment given eplerenone 400 mg, the steady-state peak plasma concentration (Cmax) and systemic exposure (AUC) of eplerenone were increased by 3.6% and 42%, respectively, compared to those in normal subjects. In 16 patients with mild to moderate hepatic impairment who received 400 mg of eplerenone, no elevations in serum potassium above 5.5 mmol/L were observed. Their mean increase in serum potassium was 0.12 mEq/L compared to 0.13 mEq/L in normal controls. No adjustment of the starting dosage is recommended for patients with mild to moderate hepatic impairment. The use of eplerenone in patients with severe hepatic impairment has not been evaluated, thus caution is advised.

Fluconazole is primarily eliminated by the kidney. Patients with renal impairment may be at greater risk for adverse effects from fluconazole due to decreased drug clearance. Dosage adjustments are recommended for patients with moderate to severe renal impairment (CrCl <= 50 mL/min) receiving multiple doses of the drug.