Drug Interaction Report

GENERALLY AVOID: Coadministration with potent inducers of CYP450 3A4 may significantly decrease the plasma concentrations of zaleplon. According to the prescribing information, CYP450 3A4 is a minor metabolizing enzyme of zaleplon. When zaleplon was coadministered with the potent CYP450 3A4 inducer rifampin (600 mg daily for 14 days), zaleplon plasma concentration (Cmax) and systemic exposure (AUC) decreased by approximately 80%. Reduced efficacy of zaleplon may occur.

MANAGEMENT: The use of zaleplon with potent CYP450 3A4 inducers should generally be avoided. An alternative sedative hypnotic agent that is not a CYP450 3A4 substrate may be considered in patients taking CYP450 3A4 inducers such as rifampin, phenytoin, carbamazepine, and phenobarbital.

ADJUST DOSING INTERVAL: Fat-rich food enhances the absorption of mitotane. One study evaluated blood levels of mitotane (o,p'-DDD) after subjects ingested a single dose of 2 g administered using various delivery vehicles (e.g., tablets, granules, milk, chocolate or oil emulsion). Mitotane plasma levels were significantly higher for milk, chocolate, and oil emulsion when compared to those who received tablets or granules alone. In the same study, mitotane levels were evaluated in subjects following long-term treatment (total dose of 200 g over 30 to 60 days) in tablet, oil emulsion, or milk formulations. Significantly higher mean plasma levels were recorded in subjects who received mitotane as an oil emulsion or mixed in milk, when compared to tablets alone. Additionally, the recovery of o,p'-DDD from the feces was about 5 times higher in subjects who received tablets alone, suggesting absorption was reduced when compared to subjects who received mitotane mixed with a fat-rich vehicle (e.g., oil emulsion or milk).

GENERALLY AVOID: Concomitant use of mitotane with central nervous system (CNS) depressants, including alcohol, may potentiate adverse effects such as somnolence and sedation.

MANAGEMENT: According to product labeling, mitotane tablets should be taken during meals containing fat-rich food (e.g., milk, chocolate, or oil) and with a full glass of water. Patients should be advised to avoid or limit consumption of alcohol and to avoid activities requiring mental alertness such as driving or operating hazardous machinery until they know how the medication affects them.

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of zaleplon. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

ADJUST DOSING INTERVAL: Administration of zaleplon with a high-fat or heavy meal may delay the onset of hypnotic effects. In healthy adult subjects, administration of zaleplon with a high-fat meal resulted in a 2-hour delay in the time to reach peak plasma drug concentration (Tmax) and a 35% reduction in the peak plasma drug concentration (Cmax) compared to fasting. Zaleplon systemic exposure (AUC) and elimination half-life were not significantly affected.

MANAGEMENT: Patients receiving zaleplon should be advised to avoid the consumption of alcohol. For faster sleep onset, zaleplon should not be administered with or immediately after a high-fat or heavy meal.