Role of Transporters in Drug Distribution

Transporters are critical in the function of capillary endothelium, where they contribute to the blood-brain, blood-germinal epithelium (blood-testis and blood-ovary), and blood-placental barriers. Endothelial cells in each of these tissues express high levels of MDR-1. The existence of a blood-brain barrier is well established and is thought to arise 

Many tissues also express the same drug export pumps that occur in the barrier epithelial tissues (e.g./ MDR/ MRP/ MXR)/ and these may be important in normal tissues/ as well as in drug-resistant cancers. For example/ P-gp may contribute to resistance to pep-tidomimetic HIV protease inhibitors (e.g./ indinavir/ saquinavir/ and nelfinavir) in AIDS patients. These drugs are substrates for P-gp/ and this transporter 

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