Halofantrine Erythromycin

Erythromycin (especially intravenous use), halofantrine, some quinolones Amisulpride, haloperidol, sertindole, thioridazine, pimozide Cisapride... 

Abacavir Adinazolam 5-Aminosalicylic acid Atorvastatin Avitriptan Bromazepam Bumetanide Celecoxib CGP 43371 Clodronate Cyclosporin Danazol Didanosine Erythromycin Fexofenadine Furosemide Ganciclovir Halofantrine Inidnavir Itraconazole Levofloxacin Methotrexate Nifedipine Pravastatin Rifabutin Stavudine Tacrine... 

Erythromycin inhibited halofantrine metabolism in vitro, suggesting that increased cardiotoxicity might be clinically important (76). 

Clinically important, potentially hazardous interactions with alcohol, amiodarone, amphotericin B, cisapride, clonidine, digitalis, diltiazem, disopyramide, erythromycin, glucocorticoids, halofantrine, haloperidol, hypokalemic diruretics, imipramine antidepressants, levodopa, lithium, pentamidine, pimozide, quinidine, sotalol, stimulant laxatives, tetracosactides, thioridazine... 

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. 

A study in animals found that ketoconazole roughly doubled the AUC of halofantrine and inhibited its metabolism to the equipotent metabolite, desbutylhalofantrine. In in vitro studies, ketoconazole markedly inhibited the metabolism of halofantrine by CYP3A4. It has been suggested that the rise in halofantrine levels could reasonably be expected to increase toxicity. Other CYP3A4 inhibitors, diltiazem and erythromycin, also inhibited the metabolism of halofantrine in vitro, and might therefore do so clinically. The manufacturer recommended caution with the concurrent use of potent CYP3A4 inhibitors. Further study is needed of these potential pharmacokinetic interactions. Mefloquine, quinine and quinidine may also inhibit the metabolism of halofantrine by CYP3A4, see (b) below. 

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