Drug Interactions between tazemetostat and zaleplon

GENERALLY AVOID: Consumption of grapefruit or grapefruit juice during tazemetostat therapy may significantly increase the plasma concentrations of tazemetostat. The proposed mechanism is inhibition of the CYP450 3A4-mediated metabolism of tazemetostat by certain compounds in grapefruit. Because grapefruit juice inhibits primarily intestinal rather than hepatic CYP450 3A4, the magnitude of interaction is greatest for those drugs that undergo significant presystemic metabolism by CYP450 3A4 (i.e., drugs with low oral bioavailability). According to the product labeling, coadministration of tazemetostat (400 mg twice daily) with the moderate CYP450 3A4 inhibitor fluconazole increased the tazemetostat steady state exposure (AUC 0 to 8 hours) by 3.1-fold and peak plasma concentration by 2.3-fold. 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. Pharmacokinetic interactions involving grapefruit juice are also subject to a high degree of interpatient variability, thus the extent to which a given patient may be affected is difficult to predict. Clinically, this interaction may result in an increased risk of the frequency or severity of adverse reactions due to tazemetostat such as hemorrhage, pleural effusion, skin infection, dyspnea, pain, and respiratory distress.

MANAGEMENT: The manufacturer advises that patients treated with tazemetostat should avoid consumption of grapefruit or grapefruit juice.

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.