AVERAGE PARAMETERS IN BIOAVAILABILITY STUDIES - AN APPLICATION TO SLOW-RELEASE AMITRIPTYLINE FORMULATION

In order to assess the extent and the rate of absorption in bioavailab ility studies, area under the curve (AUC), experimental maximum concen tration (Cmax) and experimental time to reach Cmax (Tmax), are used. B ut when slow-release formulations are considered, the drug concentrati on-time curves usually show multiple peaks, and it is difficult to com pute a Cmax and Tmax value. In case a Cmax value is computed, importan t variability in this parameter results in high values in the residual variance of the ANOVA test. So in order to decrease the high variabil ity, average parameters: average concentration (Cav), average maximum concentration (Cmax,av) and Cmax,av x 100/Cav (%Cmax,av), are proposed . These new parameters were applied in a bioavailability study of slow -release amitriptyline formulation.