MDR gene is a p-glycorprotein, an energy-dependent pump that serves to remove exogenous toxins or endogenous metabolites from the cell. It is found in a wide range of normal tissues. That includes: adrenal tissue, cells lining the renal tubule, cells lining the jejunum and colon, cells lining the bile canaliculi, & endothelial cells of capillaries in the brain and testes. CHEMOTHERAPY AGENTS NOT AFFECTED BY MDR: 1. Cyclophosphamide 2. Platinum 3. Methotrexate CHEMOTHERAPY AGENTS THAT ARE AFFECTED BY MDR: 1. Anthracyclines 2. Vinca Alkaloids 3. Taxol 4. Etoposide 5. Plicamycin 6. Mitomycin How to overcome MDR-1?mediated drug resistance? Many agents directly inhibit the P-glycoprotein pump: amphotericin B, colchicine, diltiazem, cyclosporine, erythromycin, hormones, verapamil, & VX-170.
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