Bioavailability And Bioequivalence Studies

Bioavailability And Bioequivalence Studies Each year so many drugs loss their patent protection and opens the door for the generic alternatives. In this way Bioavailability and Bioequivalence studies becomes most important. Bioavailability is defined as â€Å"The rate and extent to which the active moiety is absorbed from a drug product and becomes available at the site of action.† Bioavailability can be generally documented by a systematic exposure profile obtained by measuring drug and/metabolite concentration in the systemic circulation over a particular time period. Scope of Bioavailability studies: Development of new formulations of the already existing drugs. Determination of effect of excipients, patient related factors and possible drug To ensure the of quality of a drug product during the early stages of marketing in order to determine the influence of manufacturing factors, storage and stability factors on drug absorption. The systemic exposure profile of drug or metabolite obtained by measuring concentratio n in the systemic circulation over a particular time period during clinical trials in the early stages of drug development can serve as a benchmark for subsequent bioequivalence studies. Bioequivalence is a relative term which shows the absence of a significant difference in the rate and extent to which the active ingredient becomes available at the site of drug action when two or more identical dosage forms administered at the same molar dose under similar conditions. Bioequivalence mainly focus release of drug substances from its dosage forms and subsequent absorption into the systemic circulation i.e. test dose plasma concentration-time will be identical with reference dose plasma concentration-time without showing any significant statistical differences ,then test dosage form will consider as therapeutically equivalent to the reference dosage form . Scope of Bioequivalence studies: To establish relativity between different formulations used during the development of a new produc t. The therapeutic equivalence of a generic product and the reference product can be demonstrated. Development of a modified release form of a product which has already approved as an immediate release formulation. Development of alternative salt form for pharmaceutically equivalent drugs. Bioequivalence studies are designed to establish equivalence between the test and reference products. If test and reference products are found to be bioequivalent,by this one can expect that the test product will also be therapeutically effective. Bioanalytical method validation includes all of the procedures that demonstrate that a particular method used for quantitative measurement of analytes in a given biological matrix, such as blood, plasma, serum or urine is reliable and reproducible for the intended use. Bioanalytical method validation parameters: Accuracy Precision Selectivity Sensitivity Reproducibility Stability Validation documentation is done, by using specific laboratory investigatio ns ,which ensures that the performance characteristics of the method is suitable for the intended analytical use. The analytical method is applicable only when the validation parameters are in acceptable range. Types of validation: A. Full Validation Developing and implementing a bioanalytical method for the first time. Full validation is required for a new drug entity. If metabolites are added to an existing assay for quantification full validation is required. B. Partial Validation: