An Evaluation of the Potential of Cytochrome P450 3A4-Mediated Drug- Drug Interactions with Desvenlafaxine Use

A series of 3 open-label, 2-period, sequential studies were conducted to assess the impact of desvenlafaxine on cytochrome P450 3A4 (CYP3A4) enzyme-mediated metabolism, and the effect of CYP3A4 inhibition on desvenlafaxine metabolism. Study 1 evaluated a single dose of desvenlafaxine 400 mg administered alone or with a CYP3A4 inhibitor (ketoconazole [400 mg/d for 8 days]). Studies 2 and 3 evaluated a single dose of CYP3A4 substrate (midazolam [4 mg]) administered alone or with multiple doses of desvenlafaxine 400 mg and 50 mg (the recommended therapeutic dose), respectively, to assess the potential inhibitory effect of desvenlafaxine. In study 1, desvenlafaxine peak plasma concentration (Cmax) and area under the plasma concentration-versus-time curve (AUC) geometric least-squares mean ratios (desvenlafaxine and ketoconazole vs. desvenlafaxine alone) were 108% (90% confidence interval [CI], 100% to 117%) and 143% (90% CI, 138% to 149%), respectively. Total oral clearance decreased by 29% with ketoconazole coadministration. In studies 2 and 3, Cmax and AUC geometric least-squares mean ratios (midazolam and desvenlafaxine vs. midazolam alone) were 84% (90% CI, 72% to 97%) and 69% (90% CI, 61% to 78%), respectively, for the desvenlafaxine 400-mg dose, and 86% (90% CI, 79% to 94%) and 71% (90% CI, 65% to 78%), respectively, for the desvenlafaxine 50-mg dose. No serious adverse events or safety-related discontinuations occurred. Desvenlafaxine is minimally metabolized by CYP3A4 and does not appear to inhibit CYP3A4.