Abstract Introduction: The immediate-release solid oral products containing very soluble and permeable drugs are candidates for the biowaiver process. This work aims to compare in vitro, in silico, and in vivo data to establish if previously published prednisone oral tablet formulations are biowaiver candidates. Method: To achieve this goal, permeation studies were conducted on Caco-2 cells. A previous bioequivalence study between the test and the reference drug product was applied on an in silico evaluation using Gastroplus® to assess the bioequivalence of two other previously proposed formulations. Results: The apparent permeability coefficient for prednisone presented a value of 3.69 x 10-5 cm/s in 180 minutes. The bioequivalence study shows that the tested and reference product was equivalent. The in silico simulations successfully predicted the pharmacokinetics of the tested and the other two formulations since they were validated with the in vivo study. Both exhibit the same plasma concentration vs. time profiles. Conclusions: Through the in silico results, it is possible to infer that the other two formulations tested may be bioequivalent concerning the reference product. This result may be helpful in biowaiver requesting. Toward to reduce costs and the use of human beings in bioequivalence studies, this approach could be an essential way to work in the pharmaceutical industry.

Resumen Introducción: Los productos orales sólidos de liberación inmediata que contienen fármacos muy solubles y permeables son candidatos para el proceso de bioexención. Este trabajo tiene como objetivo comparar datos in vitro, in silico e in vivo para establecer si las formulaciones de comprimidos orales de prednisona publicadas anteriormente son candidatas a la bioexención. Método: Para lograr este objetivo se realizaron estudios de permeación en células Caco-2. Se aplicó un estudio de bioequivalencia previo entre la formulación de prueba y el medicamento de referencia en una evaluación in silico utilizando Gastroplus® para evaluar la bioequivalencia de otras dos formulaciones propuestas anteriormente. Resultados: El coeficiente de permeabilidad aparente para prednisona presentó un valor de 3,69 x 10-5 cm/s en 180 minutos. El estudio de bioequivalencia muestra que el producto probado y de referencia era equivalente. Las simulaciones in silico predijeron con éxito la farmacocinética de las formulaciones probadas y las otras dos, ya que fueron validadas con el estudio in vivo . Ambos exhiben los mismos perfiles de concentración plasmática frente a tiempo. Conclusiones: A través de los resultados in silico , es posible inferir que las otras dos formulaciones ensayadas pueden ser bioequivalentes respecto al producto de referencia. Este resultado puede ser útil en la solicitud de bioexenciones. Para reducir los costos y el uso de seres humanos en los estudios de bioequivalencia, este enfoque podría ser una forma esencial de trabajar en la industria farmacéutica.

The recommended treatment for latent tuberculosis (TB) infection in adults is a daily dose of isoniazid (INH) 300 mg for six months. In Brazil, INH was formulated as 100 mg tablets. The treatment duration and the high pill burden compromised patient adherence to the treatment. The Brazilian National Programme for Tuberculosis requested a new 300 mg INH formulation. The aim of our study was to compare the bioavailability of the new INH 300 mg formulation and three 100 mg tablets of the reference formulation. We conducted a randomised, single dose, open label, two-phase crossover bioequivalence study in 28 healthy human volunteers. The 90% confidence interval for the INH maximum concentration of drug observed in plasma and area under the plasma concentration vs. time curve from time zero to the last measurable concentration “time t” was 89.61-115.92 and 94.82-119.44, respectively. The main limitation of our study was that neither adherence nor the safety profile of multiple doses was evaluated. To determine the level of INH in human plasma, we developed and validated a sensitive, simple and rapid high-performance liquid chromatography-tandem mass spectrometry method. Our results showed that the new formulation was bioequivalent to the 100 mg reference product. This finding supports the use of a single 300 mg tablet daily strategy to treat latent TB. This new formulation may increase patients’ adherence to the treatment and quality of life.