Drug Interactions between estradiol and Ztalmy

ADJUST DOSING INTERVAL: Food enhances the oral bioavailability of ganaxolone. When administered with a high-fat meal, ganaxolone peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 3- and 2-fold, respectively, compared to administration under fasted conditions. Ganaxolone was administered with food in the premarketing study population. The efficacy of ganaxolone when administered in the fasted state is unknown.

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

MANAGEMENT: Ganaxolone must be administered with food according to the manufacturer. 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.

Coadministration with grapefruit juice may increase the bioavailability of oral estrogens. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits. In a small, randomized, crossover study, the administration of ethinyl estradiol with grapefruit juice (compared to herbal tea) increased peak plasma drug concentration (Cmax) by 37% and area under the concentration-time curve (AUC) by 28%. Based on these findings, grapefruit juice is unlikely to affect the overall safety profile of ethinyl estradiol. However, as with other drug interactions involving grapefruit juice, the pharmacokinetic alterations are subject to a high degree of interpatient variability. Also, the effect on other estrogens has not been studied.