The in vivo significance of in vitro test procedures for the evaluation of drug products

The last decade of this centry is now the accepted birth date of that sub-discipline of pharmacy that is now called 'biopharmceutics'. Wagner defines biopharmaceutics 'as the study of the influence of fomulation on the therapeutic activity of a drug product.' More specifically, he states that biopharmaceutics encompasses the study of the relationship between the nature and intensity of the biological effects observed in animals or man and the following factors: 1. The nature of the form of the drug (ester, salt, complex, etc). 2. The physical state, particle size, and surface area. 3. Presence or absence of adjuvants with the drug. 4. The type of dosage form in which the drug is administered. 5. The pharmaceutical process (es) used to make the dosage form. The philosophy inherent in this definition has revolutionized our thinking with respect to product development, quality control, and to the practice of pharmacy itself. Althoughthe the emphasis herein will be on quality control, the interrelationship between this and the other areas of pharmacy will be evident. The principles of quality control dictate that a wide variety of techniques be used to evaluate the quality of a dosage form. Since quality must be built into a dosage form, the pharmaceutical scientist begins the process at the research stage, continues it during the production stage, and ends it by applying the tests and procedures established by parmacopeial commissions. These stages are usually separate and distinct and, because of this, product quality has become synonymous with compliance with pharmacopeial specifications.