Predicting Oral Drug Absorption in Humans: A Macroscopic Mass Balance Approach for Passive and Carrier-Mediated Compounds
There are several models for estimating drug absorption in humans [1–8]. Both physicochemical properties of the drug and physiological/biochemical properties of the gastrointestinal tract affect the extent and/or rate of oral drug absorption. Some of these factors include: pKa, solubility and dissolution rate, aqueous diffusivity, partition coefficient, chemical and enzymatic stability, intestinal pH, transit time, gastrointestinal motility, endogenous substances such as bile salts, and exogenous substances such as nutrients (food). The systemic availability can be further reduced by first-pass hepatic metabolism. Consequently, prediction of absorption is semi-quantitative.
KeywordsAngiotensin Converting Enzyme Absorption Number Fraction Dose Wall Permeability Mass Balance Approach
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