Ms Teresa San Miguel, Spain

Bioavailability and bioequivalence have emerged as an important area of interest in the quality of medicinal products. During the International Conference of Drug Regulatory Authorities (ICDRA) held in 1991 in Ottawa, Canada, regulatory officials supported the proposal that WHO should develop global standards and requirements for the regulatory assessment, marketing authorization and quality control of interchangeable multi-source (generic) pharmaceutical products. Based on these suggestions, WHO convened consultations which led to the WHO Guidelines on Registration Requirements to Establish Interchangeability.

For a medicinal product to exert an optimal therapeutic action, the active substance should be delivered to the site of its action in an effective concentration for the desired period. To allow prediction of the therapeutic effect, the performance of the pharmaceutical form containing the active substance should be reproducible. Thus, the bioavailability of an active substance from a pharmaceutical product should be known and show the same therapeutic effect in the clinical setting. This is especially the case if one product is to be substituted for another.

Objectives of a bioequivalence study

In order to harmonize the testing of bioavailability and bioequivalence,the European Union has been involved in updating a guideline which describes the requirements for these studies. The contents of this guideline show a high level of harmonization with the WHO Guidelines on Registration Requirements to Establish Interchangeability.