Influência da alimentação na biodisponibilidade da venlafaxina administrada em cápsulas de liberação prolongada

Abstract

The success of a therapeutic treatment depends upon the bioavailability of the drug, which can be influenced by food intake. This study aimed to evaluate the influence of food in the bioavailability of two formulations of venlafaxine administered at extended-release capsules in healthy volunteers. This open, randomized, crossover clinical trial was consisted of four periods, two sequences, in which healthy adult volunteers received 01 extended-release capsule of venlafaxina 75mg of test formulation and another of reference formulation in each distinct period under fasting or fed conditions, with an interval of seven days. 24 Blood samples were collected at predetermined times. Venlafaxine concentrations were determined through a HPLC-MS/MS method. The food did not influence the venlafaxine bioavailability when the 90 percent of confidence interval for the geometric ratio between fed and fasted treatment was contained in the equivalence limits of 80-125% for AUC0-inf, AUC0-t and Cmax when compared to administration of the drug in fasting condition. Adverse events were monitored during the study. Thirty-three subjects were included, 51.5% were male (17 men) and were 48.5% female (16 women). The mean age was 28.2 years ± 8.6 years, mean weight was 66 kg ± 11.1 kg, mean height was 160 cm ± 0.1 cm and the mean body mass index (BMI) was 24.4 kg/m2 ± 3.0 kg/m2.. The most frequent adverse events were: headache representing 32.4%, drowsiness with 16.2% and nausea with 14.7% of all events. There was no significant difference in the frequency of occurrence in the groups (reference and test) related to the fasting or fed state. Regarding the pharmacokinetic parameters, in the statistical comparison, no difference was found in the AUC0-t and the AUC0-inf in the fasted versus fed conditions in the reference and test formulation groups. The Tmax was lower and the Cmax higher in both fed groups and the T1/2 was lower in the fed state in the test formulation. The confidence interval for all parameters required to evaluate the effect of food on the bioavailability of the reference and test formulations were within the range of 80-125%. Regarding the bioequivalence of drugs, both formulations in fed and fasted state were within the established range (80-125%). Although the food did change some pharmacokinetic parameters, feeding did not influence the bioavailability of venlafaxine in both reference and test formulations. The studied capsules of venlafaxine extended-release (test and reference products) showed similar bioavailability when administered a single oral dose of 75mg to healthy adult volunteers, fasting and fed and, thus, were considered bioequivalent to the rate and extent of absorption.