PT  - JOURNAL ARTICLE
AU  - W A Colburn
AU  - M Gibaldi
TI  - Pharmacokinetic model of presystemic metabolism.
DP  - 1978 Mar 01
TA  - Drug Metabolism and Disposition
PG  - 193--196
VI  - 6
IP  - 2
4099  - http://dmd.aspetjournals.org/content/6/2/193.short
4100  - http://dmd.aspetjournals.org/content/6/2/193.full
SO  - Drug Metab Dispos1978 Mar 01; 6
AB  - A pharmacokinetic perfusion model is presented that describes the disposition of drugs that are subject to both first-pass hepatic and intestinal epithelial metabolism. Equations are developed to estimate hepatic and intestinal epithelial clearances by determining drug concentrations as a function of time in both portal and peripheral vein blood after oral and iv administration, and by determining or estimating the flow rate of blood perfusing the gastrointestinal tissues. A method that can be used, under the stated conditions, to approximate the systemic availability after oral administration of drugs subject to presystemic metabolism is also developed.