Amlodipine Grapefruit juice

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. 

Josefsson M, Zackrisson AL, Ahlner J. Effect of grapefruit juice on the pharmacokinetics of amlodipine in healthy volunteers. Eur J Clin Pharmacol 1996 51(2) 189-193. 

Product labeling indicates lack of grapefruit juice interaction, but plausibility of interaction amlodipine. 

Should amlodipine be taken orally with grapefruit juice ... 

No. Chemical substances present in grapefruit juice inhibit cytochrome P450 isoenzymes involved in amlodipine metabolism. These substances decrease the first-pass metabolism of the drug and increase serum concentrations. 

Vincent J, Harris SI, Foulds G, Dogolo LC, Willavize S, Friedman HL. Lack of effect of grapefruit juice on the pharmacokinetics and pharmacodynamics of amlodipine. BrJ Clin Pharmacol (2000) 50, 455-63. 

Josefsson M, Ahlner J, Amlodipine and grapefruit juice. BrJ Clin Pharmacol (2002) 53,405. 

---