Drug Interactions between eplerenone and morphine

GENERALLY AVOID: Alcohol may potentiate the central nervous system (CNS) depressant effects of opioid analgesics including morphine and diamorphine. Concomitant use may result in additive CNS depression and impairment of judgment, thinking, and psychomotor skills. In more severe cases, hypotension, respiratory depression, profound sedation, coma, or even death may occur.

GENERALLY AVOID: Consumption of alcohol while taking some sustained-release formulations of morphine may cause rapid release of the drug, resulting in high systemic levels of morphine that may be potentially lethal. Alcohol apparently can disrupt the release mechanism of some sustained-release formulations. The interaction was observed in in vitro studies using a 24-hour morphine formulation (Avinza 30 mg capsule, available in the U.S. from Ligand Pharmaceuticals). When the capsule was mixed with 900 mL of buffer solutions containing ethanol 20% and 40%, the dose of morphine that was released was alcohol concentration-dependent, leading to a more rapid release of morphine. Although the clinical relevance of this finding is unknown, 'dose-dumping' into the bloodstream is conceivable.

MANAGEMENT: Until more information is available, patients taking sustained-release formulations of morphine should not consume alcohol or use medications that contain alcohol. In general, potent narcotics such as morphine or diamorphine should not be combined with alcohol.

GENERALLY AVOID: Coadministration with grapefruit juice may increase the plasma concentrations of eplerenone. The primary mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. Inhibition of hepatic CYP450 3A4 may also contribute. In drug interaction studies, administration of a single 100 mg dose of eplerenone in combination with grapefruit juice resulted in a 25% increase in eplerenone systemic exposure (AUC). High blood levels of eplerenone can increase the risk of side effects including hyperkalemia. In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition.

MANAGEMENT: It may be advisable for patients to avoid the consumption of grapefruit, grapefruit juice, or supplements that contain grapefruit during treatment with eplerenone.