Drug Interactions between aliskiren / hydrochlorothiazide and diroximel fumarate

GENERALLY AVOID: Coadministration with orange, apple, or grapefruit juice may significantly decrease the oral bioavailability and renin-inhibiting effect of aliskiren. The exact mechanism of interaction is unknown, but may include inhibition of OATP2B1-mediated influx of aliskiren in the small intestine, formation of insoluble complexes between fruit juice constituents and aliskiren, and/or increased ionization of aliskiren due to reduced intestinal pH. In 12 healthy volunteers, 200 mL of either orange juice or apple juice administered three times daily for 5 days in combination with a single 150 mg oral dose of aliskiren on day 3 reduced the mean aliskiren peak plasma concentration (Cmax) and systemic exposure (AUC) by approximately 80% and 60%, respectively, compared to water. Plasma renin activity was 87% and 67% higher at 24 hours postdose when aliskiren was administered with orange juice and apple juice, respectively, compared to water. No significant differences were observed in the blood pressure or heart rate between treatments. However, this may be due to the delayed onset of aliskiren's blood pressure-lowering effect, which would not be apparent following a single dose. A similar pharmacokinetic interaction has been reported with grapefruit juice. In 11 healthy volunteers, 200 mL of normal strength grapefruit juice administered three times daily for 5 days in combination with a single 150 mg oral dose of aliskiren on day 3 reduced the mean aliskiren Cmax and AUC by 81% and 61%, respectively, but there was no change in plasma renin activity compared to water. A high degree of interpatient variability was observed with all three interactions.

MONITOR: High-fat meals can substantially reduce the gastrointestinal absorption of aliskiren. According to the product labeling, administration of aliskiren with a high-fat meal decreased the mean peak plasma concentration (Cmax) and systemic exposure (AUC) by 85% and 71%, respectively. In clinical trials, however, aliskiren was administered without a fixed requirement in relation to meals.

MANAGEMENT: To ensure steady systemic drug levels and therapeutic effects, patients should establish a routine pattern for administration of aliskiren with regard to meals. Coadministration with orange, apple, or grapefruit juice should be avoided, especially if these juices are to be consumed on a regular basis or shortly before or after aliskiren dosing.

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GENERALLY AVOID: Food does not significantly affect the oral bioavailability of diroximel fumarate. Administration of diroximel fumarate with a high-fat, high-calorie (900 to 1000 calories; 50% from fat) meal did not affect the systemic exposure (AUC) of its active metabolite, monomethyl fumarate (MMF), but decreased its peak plasma concentration (Cmax) by 44% and prolonged the time to reach peak concentration (Tmax) from 2.5 to 7.0 hours relative to administration in the fasted state. In comparison, administration of diroximel fumarate with low-fat, low-calorie (350 to 400 calories; 10 to 15 g fat) and medium-fat, medium-calorie (650 to 700 calories; 25 to 30 g fat) meals decreased the MMF Cmax by approximately 12% and 25%, respectively, while also leaving the AUC unaffected.

GENERALLY AVOID: Coadministration of diroximel fumarate with ethanol may reduce the plasma concentrations of monomethyl fumarate (MMF). The mechanism has not been reported. Following coadministration with 240 mL of 5% v/v and 40% v/v ethanol, the mean Cmax of MMF was reduced by 9% and 21%, respectively, relative to coadministration with water. The AUC of MMF was not significantly altered, indicating that ethanol did not induce dose dumping.

MANAGEMENT: Diroximel fumarate may be taken with or without food; however, high-fat, high-calorie meals or snacks should be avoided. The manufacturer recommends meals or snacks containing no more than 700 calories and no more than 30 grams of fat. Taking diroximel fumarate with food may improve tolerability for patients experiencing flushing or gastrointestinal adverse reactions. The manufacturer also recommends avoiding concomitant use of diroximel fumarate with ethanol.

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MONITOR: Many psychotherapeutic and CNS-active agents (e.g., anxiolytics, sedatives, hypnotics, antidepressants, antipsychotics, opioids, alcohol, muscle relaxants) exhibit hypotensive effects, especially during initiation of therapy and dose escalation. Coadministration with antihypertensives and other hypotensive agents, in particular vasodilators and alpha-blockers, may result in additive effects on blood pressure and orthostasis.

MANAGEMENT: Caution and close monitoring for development of hypotension is advised during coadministration of these agents. Some authorities recommend avoiding alcohol in patients receiving vasodilating antihypertensive drugs. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia.

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