Tablet testing bioequivalence studies

Hard gelatin capsules are uniquely suitable for blinded clinical tests and are widely used in preliminary drug studies. Bioequivalence studies of tablet formulations may be conveniently blinded by inserting tablets into opaque capsules, often along with an inert filler powder. Even capsule products may be disguised by inserting them into larger capsules. 

Product bioavailability is mentioned, especially where it is low. Where there are differences between the formulations tested for bioavailability during the development process and the formulation to be marketed, there is considerable discussion of the data provided on the bioequivalence of the different products and/or formulations. This is particularly so where, for example, early clinical studies were undertaken with capsules but the marketed dosage form is to be a tablet. Bioequivalence data and pharmacokinetic data (e.g., in crossover studies) and comparative dissolution studies are usually reported. This is particularly significant where the different strengths of the final products are not achieved by using different quantities of the same granulate formulation. Process optimization may also be addressed in such cases. 

The relative bioavailability of different enteric diclofenac products was investigated with normal and artificially decreased gastric acidity [63], Only one generic product was found to be fully bioequivalent. Comparison with in vitro studies concluded that the general test on enteric-coated tablets according to Ph.Eur. did not detect any difference between the four products. A modified dissolution test without mechanical stress gave an indication on differences in the lag time of the different products. 

Drug formulations The bioequivalence of oral dispersible tablets of zonisamide 100 and 300 mg and immediate-release reference capsules has been assessed in two open, randomized-sequence, single-dose, two-period, two-treatment, crossover studies the test formulation met regulatory criteria for bioequivalence [448 ]. 

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