The use of GA-RxODE (Genetics Algorithms and Running simulations from Ordinary Differential Equations-based model) method to optimize bioequivalence studies.

Bioequivalence (BE) studies are prerequisite in generic products approval. Normally, they are quite simple in design and expensive in execution, and sometimes suffer ethical questioning. Genetics Algorithms and Running simulations from Ordinary Differential Equations-based model (GA-RxODE) is a multipurpose method used in pharmacokinetic (PK) optimization. It can be used to complete concentration-time (C-T) missing data. In this investigation, GA-RxODE was applied in BE field. For this purpose, three BE studies were selected as a source data comprising formulations of metformin, alprazolam and clonazepam. From them, five blood samples values per volunteer-round from specific preset times were chosen as if BE study was carried out with five instead of the classic 10-20 samples. With the five values of each volunteer a complete C-T curve was simulated by GA-RxODE and certain PK estimation parameters (as maximum concentration, Cmax , and area under C-T curve from zero to infinite, AUCinf ) were elicited. Finally, with these modeled parameters, a BE analysis was performed according to certain regulatory agencies guidances. Some results, expressed as geometric mean ratios of compared formulations and their 90% confidence intervals (CI90), were as follows: Metformin Cmax  = 0.954 (0.878-1.035), AUCinf  = 0.949 (0.881-1.022); Alprazolam Cmax  = 1.063 (0.924-1.222), AUCinf  = 1.036 (0.857-1.249), Clonazepam Cmax  = 0.927 (0.831-1.034), and AUCinf  = 1.021 (0.931-1.119). All CI90 were inside the 0.8-1.25 BE range. In summary, the simulated data were bioequivalent and non-significantly different from original studies' data. This raises the opportunity to perform more economic BE studies to build reliable PK estimation parameters from a few samples per volunteer.

Alprazolam: Análisis de posibles diferencias farmacocinéticas debidas al sexo / Alprazolam: Analysis of possible differences pharmacokinetics due sex

Para evaluar la posible influencia del sexo en el comportamiento farmacocinético de una benzodiacepina, se adminsitró una dosis oral de 1mg de alprazolam (ALZ) a 8 varones y 8 mujeres. Se determinaron las concentrciones plasmáticas (Cp) en muestras extraídas a los tiempos: 0,05,1,1.5,2,3,4,6,7,9,10,12,24 y 48 horas. La concentración máxima (Cmax) fue de 11,73+-2,55 ng/dL y la mayoría de los tiempos para Cmax (tmax) oscilaron entre 1 y 1,5 h. El tempo de vida media (t1/2) de eliminación fue de 14,21+-5,72h y el área bajo la curva 0 a 48 h (ABC 0-48) alcanzó una magnitud de 135,16+-62,89 ng/mL.h. Los perfiles de las Cp fueron equivalentes y los diferentes parámentros evaluados no se diferenciaron en función del sexo. Todos los sujetos mostraron una buena tolerabilidad del fármaco. Con este ensayo se concluye que no hay evidencia de diferenciación en la farmacocinética del ALZ debida al factor sexo y que la realización de este tipo de ensayos contribuye a describir la posible existencia de diferencias cinéticas atribuibles al sexo.