Simultaneous itraconazole bioequivalence assessment and CYP3A phenotyping in South American subjects.

OBJECTIVE: The present study evaluates the acute effect of a single-dose itraconazole administration on CYP3A phenotype, as measured by cortisol MR ratio in urine. METHODS: Twenty-four healthy Uruguayan subjects recruited according to strict inclusion criteria participated in an open-label, randomized, two-period, crossover study designed to evaluate the bioequivalence of an itraconazole formulation (Traconal 100 mg, Achê Labs, São Paulo, Brazil). The study comprised two treatment periods separated by a wash-out period of 14 days. In each period a series of venous blood samples were drawn over 48 hours. Three urine samples were obtained for CYP3A phenotyping: pre-dose, 24 and 48 hours after dosing. Blood and urine samples were assayed for itraconazole, beta-hydroxycortisol and cortisol using a validated chromatographic method. RESULTS: The ratio of the mean AUC0-inf. T/AUC0-inf. R was included in the bioequivalence range, however, due to high variability, the CI90% was not. It was found that the cortisol metabolic ratio (MR) showed inhibition relative to basal activity in a proportion of subjects 24 hours (68 +/- 6.1%, mean +/- CI95%) and 48 hours (80 +/- 7.3%, mean +/- CI95%) after ingestion of itraconazole. A significant correlation was found between itraconazole AUC0-inf. and normalized basal CYP3A MR for the reference (r = 0.62, t = 3.72, p = 0.001) and the test product (r = 0.74, t = 5.22, p = 0.00003). A good correlation existed between basal cortisol MR and the elimination half-life of itraconazole. CONCLUSIONS: The findings are in line with the hypothesis that the determination of the bioavailability of highly variable CYP3A substrates might be improved by simultaneous non-interfering phenotyping. If this is confirmed, a new methodological paradigm may need to be developed in order to take account of metabolic variability in bioequivalence evaluation of this group of drugs.

Impact of food administration on lopinavir-ritonavir bioequivalence studies.

A bioequivalence study in 16 Caucasian healthy volunteers (eight male, eight female), comparing plasma drug concentrations after a single oral dose of lopinavir and ritonavir (400 and 100mg, respectively), was carried out following a two-period, two-sequence, two-treatment, randomized crossover design. Formulations were given 15 min after a moderate-fat breakfast in order to diminish both the intrinsic highly-variable performance and the sex differences observed in bioequivalence trials under fasting conditions. Ninety percent confidence intervals for the Test/Reference (T/R) ratio of geometric means for area under concentration-time curve (AUC) and maximum concentration (C(MAX)), either for lopinavir or ritonavir, were within the range of 0.80-1.25. Coprandial administration of formulations not only reduced the number of subjects required for bioequivalence assessment, reducing both ethical and economic cost of the trial, but also the sex differences in the T/R ratio of means.

Biodisponibilidad comparativa de tres formulaciones orales de un antiinflamatorio no esteroideo / Comparative bioavailability of three oral formulations of a non steroidal antiinflammatory

Los estudios de biodisponibilidad/bioequivalencia tienen como objetivo evaluar el desempeño biofarmacéutico de productos genéricos en relación al producto original. Estas diferencias entre productos pueden determinar tanto problemas de eficacia como de seguridad en el uso de los mismos. La autoridad sanitaria es la encargada de controlar la intercambiabilidad de genéricos. Si bien en países de la región existe un marco legal para la realización de estos estudios, Uruguay aún carece de este tipo de regulación. Este estudio se presenta con el objetivo de contribuir al desarrollo de esta área en nuestro país. Se comparó la biodisponibilidad oral de tres preparados farmacéuticos de nimesulida en 12 voluntarios sanos. Se concluye que los productos A y B tienen una biodisponibilidad similar, diferenciándose del producto C, que tiene una fracción biodisponible menor. Se describe la metodología utilizada, el procesamiento farmacocinético y estadístico de los datos, el análisis de los resultados y sus posibles repercusiones clínicas. Las consecuencias de estas diferencias en la biodisponibilidad varían con el fármaco considerado. Se presenta una lista de fármacos en la que este hecho tiene particular importancia