ABCB1 and Hypercholesterolemia: Various 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (statins) are used in the treatment of hypercholesterolemia and at least one statin, Atorvastatin, has been shown to both induce and suppress ABCB1 (ref. 5) even though others have found that statin treatment and cholesterol reduction do not affect P-gp regulation.34, 35, 36