The aim is to assess the expected in vivo bioequivalence of two alternative drug formulations. It is mainly used to determine the bioequivalence and demonstrate equivalence in biopharmaceutics between a generic product candidate and a reference product in order to allow bridging of preclinical and/or clinical trials associated with the reference product.
In case of a human pharmaceutical product it depends on the therapeutic purpose, route of administration and drug metabolism; usually dogs or minipigs are used.
Veterinary products are tested in the target species.
Usually a randomized, two-period, two-sequence single dose crossover design is preferred (unless steady-state levels of the active ingredient should be determined). Between the treatments, a wash out period is necessary to ensure that concentrations of the test item are below the bioanalytical quantification limit at the second treatment.
The in vivo bioequivalence is demonstrated if the rate and extent of absorption, as determined by statistical comparison of measured parameters derived from relevant data (e.g. concentration of the active ingredient in the blood) do not indicate a significant difference from those of the reference material.
Rate and extent of absorption is generally based on plasma concentration time curve. Selected pharmacokinetic parameters (e.g. AUC, Cmax, tmax) and preset acceptance limits allow the final decision on bioequivalence of the tested products.