Interspecies scaling: predicting oral clearance in humans.

The objective of this study was to test the interspecies scaling approach for a wide variety of drugs to predict oral clearance in humans from animal data. This study is an attempt to evaluate whether the rule of exponents of Mahmood and Balian for the prediction of systemic clearance can also be applied for the prediction of oral clearance in humans. Three different methods were used to generate log-log plots to scale up the clearance values: (1) clearance versus body weight (simple allometric equation), (2) the product of clearance and maximum life-span potential (MLP) versus body weight, and (3) the product of clearance and brain weight versus body weight. Data from 32 drugs were analyzed, and it was concluded that the oral clearance of drugs could be best predicted using one of the allometric equations.