Bioavailability Studies

Student Objectives for this Chapter

• To define various terms relating to bioavailability studies
• To understand some of the past problems with bioavailability
• To evaluate the components and results of a bioavailability
• To evaluate results from bioavailability studies study

1. two (or more) dosage forms made by two (or more) different manufacturers, e.g. innovator versus generic. Bioequivalence study looking for similarity of F and ka values between products.
2. one type of dosage form with another, e.g. tablet versus intravenous dosage form or regular tablet with sustained release tablet. Bioavailability study where ka and F are to be determined. Changes in ka may be intentional (slow release) whereas F values should be similar.

Second brand or generic drug manufacturers are required to prove that their product is equivalent to previously marketed products which have demonstrated clinical efficacy. For most drugs, the second and subsequent manufacturer must show that their product is bioequivalent, i.e. same ka and F, as the product(s) on the market. During the development of new drugs and drug products, the original manufacturer will also perform bioavailability studies on new products, comparing the product to be marketed with an intravenous dosage form, if possible.

• Albert, K.S. 1980 Drug Absorption and Disposition: Statistical Considerations Amer. Pharm. Assoc.
• Dittert, L.W. et al. 1972 Guidelines for Biopharmaceutical Studies in Man Amer. Pharm. Assoc.
• U.S. Food and Drug Administration (FDA)
  • FDA Enforcement Report Index
  • FDA Recalls and Safety Alerts
  • Electronic Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations
    • Preface
    • Therapeutic Equivalence Evaluations Codes
• Schedule of Pharmaceutical Benefits for Approved Pharmacists and Medical Practitioners from the Australian Department of Health and Ageing
  • Symbols page for the Schedule...note the equivalence symbol 'a'

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Copyright 2001-3 David W. A. Bourne (david@boomer.org)