Abstract

(1) Background: this article investigates which PK metrics in a single-dose study (con-centration at the end of posology interval, Cτ, partial areas under the curve, pAUCs, or half-value duration, HVD) are more sensitive and less variable for predicting the failure of a prolonged-release product at steady-state that was the bioequivalent for Cmax, AUC0-t and AUC0-inf, in the single-dose study; (2) Methods: a cross-over study was performed in 36 subjects receiving desvenlafaxine 100 mg prolonged-release tablets. Conventional (Cmax, AUC0-t and AUC0-inf) and additional (Cτ, pAUC sand HVD) PK metrics were considered after single-dose conditions. Predicted PK metrics at steadystate (AUC0-τ, Cmax, ss, and Cτ,ss) were derived using a population PK model approach; (3) Results: the existing differences in the shape of the concentration–time curves precluded to show equivalencefor Cτ,ss in the simulated study at steady state. This failure to show equivalence at steady state was predicted by Cτ, pAUCs and HVD in the single-dose study. Cτ was the most sensitive metricfor detecting the different shape, with a lower intra-subject variability than HVD; (4) Conclusions: conventional PK metrics for single-dose studies (Cmax, AUC0-t and AUC0-inf) are not enough to guarantee bioequivalence at steady state for prolonged-release products.

By Victor Mangas-Sanjuan, Marta Simón, Esperanza González Rojano, Dolores Ochoa, Francisco Abad-Santos, Manuel Román, Mercedes Ramos, Carlos Govantes, Alfredo García Arieta