Drug Interaction Report

Consumer information for this interaction is not currently available.

MONITOR: Coadministration with weak inhibitors of CYP450 3A4 may increase the plasma concentrations of eplerenone, which is primarily metabolized by the isoenzyme. In pharmacokinetic studies, administration of a single 100 mg dose of eplerenone in combination with the potent CYP450 3A4 inhibitor ketoconazole (200 mg twice a day) resulted in a 1.7-fold increase in eplerenone peak plasma concentration (Cmax) and a 5.4-fold increase in systemic exposure (AUC), while administration with moderate inhibitors (erythromycin 500 mg twice daily; verapamil 240 mg once daily; saquinavir 1200 mg three times daily; fluconazole 200 mg once daily) resulted in increases in eplerenone Cmax ranging from 1.4- to 1.6-fold and AUC from 2.0- to 2.9-fold. No data are available for other, less potent inhibitors.

MANAGEMENT: Caution and monitoring are recommended when eplerenone is used with weak CYP450 3A4 inhibitors. Some authorities recommend against the concomitant use of eplerenone with weak CYP450 3A4 inhibitors in patients with an eGFR of 30 to 49 mL/min/1.73m2, and not to exceed 25 mg daily if coadministration is required in patients with an eGFR higher than 50 mL/min /1.73m2.

Zafirlukast should be taken on an empty stomach 1 hour before or 2 hours after a meal unless otherwise directed by your doctor. You may experience reduced absorption of zafirlukast in the presence of food. This will make it easier for your body to absorb the medication.

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.