The biowaiver procedure: its application to antituberculosis products in the WHO prequalification programme

In 2005, the World Health Organization (WHO) proposed that provided an active pharmaceutical ingredient could meet certain criteria, bioequivalence could be evaluated with a set of laboratory tests, obviating the need for expensive and time-consuming pharmacokinetic studies in humans. The aim of this work was to determine whether this so-called "biowaiver" procedure can be applied to antituberculosis products. Antituberculosis products from the WHO Prequalification Programme, including three ethambutol, two isoniazid and one pyrazinamide product, were investigated. In vitro dissolution data for these products were generated according to the biowaiver method stipulated in the WHO Guidance, and the bioequivalence decision based on these data was compared with that based on the corresponding in vivo pharmacokinetic data. In no case was a "false positive" bioequivalence decision reached using the biowaiver procedure, that is, all products deemed bioequivalent according to the biowaiver methods also proved to be bioequivalent in the corresponding pharmacokinetic study. These findings open the way to a simplified method of ensuring bioequivalence of antituberculosis drug products, thereby improving access to high quality antituberculosis medicines for a greater number of patients.