Does GastroPlus Support Similarity and Dissimilarity Factors of in vitro-in vivo Prediction in Biowaiver Studies? A Lower Strength Amlodipine As a Model Drug.

BACKGROUND: Many generic pharmaceutical products are currently available on the market place worldwide. Recently, there is a growing concern on the quality and efficacy of generic products. However, health care professionals such as physicians and pharmacists are in difficult situations to choose among alternatives.
PURPOSE: The aim of this study is to assess the effectiveness of the in silico technique (Gastro Plus®) in the biowaiver study and whether similarity and dissimilarity factors (f 2 and f 1 respectively) are effective in this regard.
METHOD: The concentration of amlodipine in the sample was calculated by comparing the absorbance of the sample with that of a previously prepared amlodipine standard solution using validated HPLC method. The dissolution profile for each product (brand and generics) was constructed. The similarity (f2) and dissimilarity (f 1) factors were calculated for the generic product according to equation 1 and 2. GastroPlus™ software (version 9.0, Simulations Plus Inc., Lancaster, CA, USA) was used to predict the absorption profiles of amlodipine from the generic product Amlovasc® and the reference Norvasc®.
CONCLUSION: These results may provide a rationale for the interchangeability between the RLD and generic version based on in vitro release profiles in silico technique especially in a lower strength dose drug. © Georg Thieme Verlag KG Stuttgart · New York.