Methadone grapefruit juice

Benmebarek M, Devaud C, Gex-Fabry M, et al. Effects of grapefruit juice on the pharmacokinetics of the enantiomers of methadone. Clin Pharmacol Ther 2004 76(l) 55-63. 

GRAPEFRUIT JUICE METHADONE t plasma concentrations and t risk of adverse effects. Interaction is considered to be of rapid onset but of minor clinical significance Methadone is metabolized by intestinal CYP3A4, which is inhibited by grapefruit juice Prudent to be aware and warn users and carers... 

Clinically important, potentially hazardous interactions with amiodarone, astemizole, bepridil, carbamazepine, chloroquine, cisapride, clarithromycin, dihydroergotamine, disopyramide, ergotamine, grapefruit juice, halofantrine, haloperidol, itraconazole, ketoconazole, methadone, moxifloxacin, phenobarbital, phenytoin, pimozide, procainamide, quinidine, rifampicin, ritonavir, sotalol, St John s wort, telithromycin, terfenadine, voriconazole... 

Grapefruit juice has been associated with a modest increase in oral methadone bioavailability. Grapefruit juice does not appear to affect the bioavailability of intravenous alfentanil or transmu-cosal fentanyl to a clinically significant extent the clearance of oral alfentanil may be reduced. 

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