Quinine Grapefruit juice

Inhibitors of the CYP3A4 isoenzyme could increase systemic dofetilide exposure. Inhibitors of this isoenzyme (e.g., macrolide antibiotics, azole antifungal agents, protease inhibitors, serotonin reuptake inhibitors, amiodarone, cannabinoids, diltiazem, grapefruit juice, nefazadone, norfloxacin, quinine, and zafirlukast) should be cautiously coadministered with TIKOSYN, because they can potentially increase dofetilide levels... 

GRAPEFRUIT JUICE QUININE Report of 1 heart rate and PR that returned to normal 4-6 hours after intake of quinine. Not considered to be clinically significant Due to inhibition of metabolism of CYP3A4-mediated metabolism. However, metabolism of quinine is predominantly hepatic and thus unaffected by grapefruit juice Be aware... 

Clinically important, potentially hazardous interactions with amiodarone, azithromycin, bepredil, bosentan, bretylium, cisapride, clarithromycin, disopyramide, erythromycin, erythromycin fluconazole, fluoxetine, fluvoxamine, grapefruit juice, indinavir, itraconazole, ketoconazole, metronidazole, miconazole, nefazodone, nilotinib, paroxetine, pimozide, probucol, procainamide, quinidine, quinine, ritonavir, saquinavir, sertraline, sotalol, SSRIs, terfenadine, troleandomycin, voriconazole, zileuton, ziprasidone... 

A4 Amiodarone, azole antifungals, cimetidine, clarithromycin, cyclosporine, erythromycin, fluoroquinolones, grapefruit juice, HIV protease inhibitors, metronidazole, quinine. SSRIs, tacrolimus Antiarrhythmics, antidepressants, azole antifungals, benzodiazepines, calcium channel blockers, cyclosporine, delavirdine, doxorubicin, efavirenz, erythromycin, estrogens, HIV protease inhibitors, nefazodone. paclitaxel, proton pump inhibitors, HMG-CoA reductase inhibitors, rifabutin, rifampin, sildenafil, SSRIs, tamoxifen, trazodone, vinca anticancer agents... 

Pyrimethamine/sulfadoxine and tetracycline have been shown to increase halofantrine levels, and may therefore increase its toxicity. Diltiazem, erythromycin, ketoconazole, mefloquine, quinine, and quinidine might also increase the toxicity of halofantrine because they have been shown to inhibit its metabolism in vitro. The manufacturer has therefore recommended caution with the concurrent use of potent CYP3A4 inhibitors. Fatty food markedly increases halofantrine levels, consequently it is recommended that halofantrine is taken on an empty stomach. Grapefruit juice has a similar effect Note that halofantrine is no longer widely marketed. 

Grapefruit juice is a known inhibitor of intestinal cytochrome P450 isoenzyme CYP3A4, and it appears that this has little effect on the pharmacokinetics of quinine, which has a high oral bioavailability and is metabolised in the liver. 

Grapefruit juice does not alter the pharmacokinetics of quinine, suggesting that patients requiring quinine may safely drink grapefruit juice if they wish. ... 

Ho PC, Chalcroft SC, Coville PF, Wanwimolruk S, Grapefruit juice has no effect on quinine pharmacokinetics. EurJ Clin Pharmacol (1999) 55, 393-8. 

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