Centers for Education &
Research on Therapeutics™
Marchietti S, et al. Clinical relevance of drug-drug and herb-drug interactions mediated by the ABC transporter ABCB1 (MDR1, P-glycoprotein). The Oncologist 2007;12:927-41.
P - Glycoprotein Tissue Distribution
The anatomical localization of PGP suggests that it can play a physiological role in detoxification and protection against toxic xenobiotics and metabolites.  It is found in various tumors where it confers the multi-drug resistance (MDR) phenotype.  It is also found in the apical/luminal membrane of polarized cells in several normal human tissues with excretory function (liver, kidney, adrenal gland) and barrier function (intestine, blood-brain barrier, placenta, blood–testis and blood–ovarian barriers).  Excreting foreign compounds into bile, urine, and the intestinal lumen prevents their accumulation in the brain, testis, and fetus and can protect the organism against harm.1

1. Marchetti S, Mazzanti R, Beijnen JH, Schellens JH. Concise review: Clinical relevance of drug drug and herb drug interactions mediated by the ABC transporter ABCB1 (MDR1, P-glycoprotein). Oncologist 2007; 12(8):927-941.