Grapefruit juice inhibits metabolism of ivabradine
Clinical evidence,mechanism, importance and management
Grapefruit juice increases exposure to ivabradine exposure twofold. This interaction probably occur because grapefruit inhibits cytochrome P450 isoenzyme CYP3A4 in intestine, by which ivabradine is metabolised. This leads to increased levels, which increases risks of adverse effects such as profound bradycardia The manufacturers recommend that intake of grapefruit juice by patients also taking ivabradine is restricted (See reference number 1). However, note that they contraindicate use of other drugs that increase ivabradine levels by a similar amount, and so it would seem that concurrent use is best avoided.
1. Procoralan (Ivabradine hydrochloride) Servier Laboratories Ltd. UK Summary of productcharacteristics,March 2007.