Drug Interaction Report

MONITOR: Coadministration of medicines targeting the prostacyclin pathway (e.g., prostacyclin (PGI2), PGI2 analogs, or selective non-prostanoid prostacyclin IP receptor agonists) with diuretics, antihypertensive agents, or other vasodilators may potentiate the hypotensive effects of these agents. The mechanism involves the additive reduction in blood pressure due to the vasodilatory effects of PGI2, PGI2 analogs or selective non-prostanoid prostacyclin IP receptor agonists on the prostacyclin pathway.

MANAGEMENT: While therapies that target the prostacyclin pathway have been used in combination with diuretics, antihypertensives, or other vasodilators in the management of pulmonary arterial hypertension, caution is recommended if they must be administered concurrently. If these drugs are used together, it is generally recommended that blood pressure be measured more frequently until a stable blood pressure pattern is observed. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their doctor if they experience dizziness, lightheadedness, syncope, orthostatic hypotension, or tachycardia. Treatment guidelines should be consulted for the optimum management of pulmonary arterial hypertension.

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.

Food prolongs the gastrointestinal absorption of selexipag. When taken with food, the time to peak concentration (Tmax) was delayed and peak plasma concentration (Cmax) was approximately 30% lower. Selexipag systemic exposure (AUC) and that of its active metabolite did not significantly change, however. Selexipag may be taken with or without food. Tolerability may be improved when taken with food.