BIOWAIVER STUDIES
Clinical BE study is not possible for the drug products which do not undergo Systemic Circulation. For such products, FDA recommends In Vitro Bioequivalence Studies, also called In Vitro binding studies or Bio waiver studies in lieu of clinical BE study. There are several products such as Sevelamer HCL Tablets, Sevelamer carbonate, Colesevelam Hydrochloride Tablets, Colesevelam Hydrochloride Capsules, Cholestyramine Powder for Suspension etc which falls under this category.
Objective of In Vitro BE study is to compare the affinity and capacity binding constants of bile acid salts/phosphate with resin in a generic formulation with that in the reference formulation under identical experimental conditions.
Generally, this study is conducted by incubating the test (T) and reference (R) products with at least eight different concentrations of total bile salts/phosphate, with and without acid pre-treatment. For the in vitro equilibrium binding study, the Langmuir binding constants k1 and k2 are determined based on total bile salt/phosphate binding
Generally, this study is conducted by incubating the test (T) and reference (R) products with at least eight different concentrations of total bile salts/phosphate, with and without acid pre-treatment. For the in vitro equilibrium binding study, the Langmuir binding constants k1 and k2 are determined based on total bile salt/phosphate binding