title: Can absolute oral bioavailability in humans be predicted from animals? A comparison of allometry and different indirect methods.
abstract: The objective of this study was to predict absolute bioavailability in humans from animal data using interspecies scaling as well as indirect approaches. Five different methods were used to predict absolute bioavailability in humans: (i) absolute bioavailability vs body weight (allometric approach); (ii) F = CL(IV)/CL(oral); (iii) F = 1-[CL(IV)/Q]; (iv) F = 1-[CL(oral)/Q]; and (v) F = Q/[Q + CL(oral)]. Methods II-V are indirect approaches, where predicted i.v. or oral clearance and hepatic blood flow (Q) (1500 ml/min) were used to predict absolute bioavailability in humans. Fifteen drugs were tested and the results of this study indicate that all five approaches predict absolute bioavailability with different degrees of accuracy, and are therefore unreliable for the accurate prediction of absolute bioavailability in humans from animal data. In conclusion, although the above-mentioned approaches do not accurately predict absolute bioavailability, a rough estimate of absolute bioavailability is possible using these approaches.
authors.affiliation: Division of Pharmaceutical Evaluation I (HFD-860), Food & Drug Administration, Woodmont Office Center II, Rockville, MD 20852, USA. Mahmoodi@CDER.FDA.GOV
authors.forename: I
authors.initials: I
authors.lastname: Mahmood
mesh_terms: D000818:Animals; D001682:Biological Availability; D001835:Body Weight; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D003627:Data Interpretation, Statistical; D015195:Drug Design; D006207:Half-Life; D006801:Humans; D008657:Metabolic Clearance Rate; D010599:Pharmacokinetics; D011237:Predictive Value of Tests; D013045:Species Specificity; D014018:Tissue Distribution