In vitro-in vivo Pharmacokinetic correlation model for quality assurance of antiretroviral drugs / Modelo de correlación farmacocinético in vitro-in vivo para el aseguramiento de la calidad de medicamentos antirretrovirales

Introduction: The in vitro-in vivo pharmacokinetic correlation models (IVIVC) are a fundamental part of the drug discovery and development process. The ability to accurately predict the in vivo pharmacokinetic profile of a drug based on in vitro observations can have several applications during a successful development process. Objective: To develop a comprehensive model to predict the in vivo absorption of antiretroviral drugs based on permeability studies, in vitro and in vivo solubility and demonstrate its correlation with the pharmacokinetic profile in humans. Methods: Analytical tools to test the biopharmaceutical properties of stavudine, lamivudine y zidovudine were developed. The kinetics of dissolution, permeability in caco-2 cells and pharmacokinetics of absorption in rabbits and healthy volunteers were evaluated. Results: The cumulative areas under the curve (AUC) obtained in the permeability study with Caco-2 cells, the dissolution study and the pharmacokinetics in rabbits correlated with the cumulative AUC values in humans. These results demonstrated a direct relation between in vitro data and absorption, both in humans and in the in vivo model. Conclusions: The analytical methods and procedures applied to the development of an IVIVC model showed a strong correlation among themselves. These IVIVC models are proposed as alternative and cost/ effective methods to evaluate the biopharmaceutical properties that determine the bioavailability of a drug and their application includes the development process, quality assurance, bioequivalence studies and pharmacosurveillance.

Introducción: Los modelos de correlación In vitro-in vivo (IVIVC) son parte integral del proceso de investigación y desarrollo de fármacos. La capacidad de predecir con exactitud el perfil in vivo a partir de las observaciones in vitro tiene diversas aplicaciones durante el desarrollo exitoso de una formulación. Objetivo: Desarrollar un modelo integral para predecir la absorción in vivo de fármacos antirretrovirales con base en estudios de permeabilidad, solubilidad in vitro e in vivo y demostrar su correlación con la farmacocinética en humanos. Métodos: Se desarrollaron y validaron las técnicas bioanalíticas para valorar las propiedades biofarmacéuticas de Estavudina, Lamivudina y Zidovudina. Se evaluó las cineticas de disolución, la permeabilidad en monocapas celulares Caco-2 y la farmacocinética de absorción in vivo en conejos y voluntarios sanos. Resultados: Los valores de AUC acumulados en el sistema de células Caco-2, en la disolución y en el modelo animal, fueron correlacionados con los valores de AUC acumulados en el humano. Con lo anterior se demostró una relación directamente proporcional entre los resultados in vitro con respecto a los obtenidos en la fase de absorción tanto en el humano como en el modelo animal. Conclusiones: Los métodos analíticos y procedimientos aplicados en la IVIVC demostraron las correspondencias directas entre sí, con altos niveles de correlación. Se proponen estos modelos IVIVC como métodos alternativos costo/efectivos para la valoración de las propiedades biofarmacéuticas que determinan la biodisponibilidad, en el desarrollo de productos, en el aseguramiento de la calidad y como pruebas de bioequivalencia en los programas de farmacovigilancia.

Chemometric optimization for simultaneous determination of anti-retroviral drugs by RP-HPLC

This work deals with multiple response simultaneous optimization using the Derringer's desirability function for the development of a reversed phase HPLC method for the simultaneous determination of lamivudine, tenofovir and efavirenz in commercial pharmaceutical preparations. Twenty experiments, taking the capacity factor of the first peak, resolution between the second and third peaks and the retention time of the third peak as the responses with three important variables as organic phase composition, buffer molarity, and flow rate, were used to design mathematical models. The experimental responses were fitted into a second order polynomial and the three responses were simultaneously optimized to predict the optimum conditions for the effective separation of the studied compounds. The optimum assay conditions were: methanol-triethylamine buffer [pH 3.0; 15.3 mM] [35:65%v/v] as the mobile phase and at a flow rate of 1.19 ml/min. While using this optimum condition, a baseline separation with a minimum resolution of 2.0 and a run time of less than 6 min was achieved. The method showed a good agreement between the experimental data and predictive value throughout the studied parameter space. The optimized assay condition was validated according to the International Conference on Harmonization guidelines to confirm specificity, linearity, accuracy, and precision.

HIV/AIDS treatment and physicochemical quality control of medicines: evaluation of non-generic lamivudine + zidovudine tablets manufactured in Brazil

In this work it was evaluated the physicochemical quality of lamivudine + zidovudine tablets, whose association belongs to the list of drugs distributed by the Brazil's National Program on Sexually Transmitted Diseases and AIDS. Four non-generic products (lamivudine + zidovudine tablets) were analyzed. They were obtained from different Brazilian manufacturers, besides a reference product. The quality was evaluated by physicochemical tests described in the official codes. A validated reversed-phase high performance liquid chromatography (HPLC) method was used for the assay of the active substances. All samples were in accordance to the requisites in relation to their physicochemical characteristics. Dissolution studies showed similar drug percentual dissolved among all samples. The results reflect the interest of the national pharmaceutical industry to ensure the delivery of safer and cheaper drugs to the Brazilian people, with particular importance in the National Program on Sexually Transmitted Diseases and AIDS.