The CYP450 enzymes are essential for the production of numerous agents including cholesterol and steroids. Additionally, these enzymes are necessary for the detoxification of foreign chemicals and the metabolism of drugs. Drugs that are CYP450 inhibitors block the metabolic activity of one or more of the CYP450 enzymes. The extent to which an inhibitor affects the metabolism of a drug depends upon factors such as the dose and the ability of the inhibitor to bind to the enzyme.
Calcium channel blockers (CCBs) are used in the treatment of many cardiovascular conditions. They are divided into subclasses, non-dihydropyridines and dihydropyridines. The non-dihydropyridine CCBs cause less vasodilation and more cardiac depression than dihydropyridine CCBs (hence why they are not recommended in decompensated heart failure). They cause reductions in heart rate and contractility. Dihydropyridine CCBs have more vascular selectivity and fewer cardiac effects. They are indicated in the treatment of hypertension and angina. They do not suppress AV conduction or the SA node automaticity.