Grapefruit juice--drug interactions: importance for pharmacotherapy.

In spite of known health benefits of grapefruit juice, its consumption in combination with drugs requires caution. The drugs most susceptible to pharmacokinetic interactions with clinical significance are those with narrow therapeutic index and low bioavailability due to important first-pass metabolism. Most vulnerable populations are elderly, cirrhotics, subjects with genetic polymorphisms and individuals taking other CYP3A4 inhibitors. The major drug classes that have been reported to present interactions with grapefruit juice are antiallergics, antibiotics, antimalaria drugs, anxiolytics, calcium channel blockers, HIV protease inhibitors, HMG-CoA reductase inhibitors; the degree of pharmacokinetic interaction varies among the compounds of the same class.