Dihydropyridines drug interactions

Amlodipine shows a preference for binding vascular smooth muscle cells over cardiac muscle cells, thus acting as a peripheral arterial vasodilator (Pfizer, Inc. 2005). Like most other CCB dihydropyridines, amlodipine is highly protein bound and heavily metabolized. In contrast to felodipine, this compound is not influenced by grapefruit juice and appears to show fewer drug-drug interactions. 

Katoh M, Nakajima M, Shimada N, et al. Inhibition of human cytochrome P450 enzymes by 1,4-dihydropyridine calcium antagonists prediction of in vivo drug-drug interactions. Eur J Clin Pharmacol 2000 55 843-852. 

Drug interactions Increased levels of digoxin, carbamazepine, cyclosporine, theophylline additive AV nodal block with concurrent beta-blockers Grapefruit juice may in-aease levels of some dihydropyridine agents ... 

There are two groups dihydropyridines and diltiazem/verapamil. Both groups are metabolized by the CYP3A family of isoenzymes (especially CYP3A4), which are the sites of many of the pharmacokinetic interactions involving this class. Some drugs are substrates for P-gp. 

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