Application of Stable Isotope Method in Study Bioavailability and Bioequivalence of Highly Variable Drugs and Formulations

KEITH K.H. CHAN

Pharmaceuticals Division, Ciba-Geigy Corporation Ardsley, New York 10502, U.S.A.

ABSTRACT

   The stable isotope method has been used successfully in bioavailability studies for highly variable drugs that have extensive first-pass metabolism and exhibit large intra-subject variation in clearance. Recently this technique has been extended to bioequivalence studies where labeled solution is intravenously infused in both occasions while test and reference formulation are administered. This report discusses the advantages and disadvantages of the stable isotope method and its application in bioavailability and bioequivalence studies of highly variable drugs and drug delivery systems.

Key words : Stable isotope method, Bioavailability, Bioequivalence, Highly variable drugs and formulations .