Nefazodone Astemizole

Contraindications Co-administration of terfenadine, astemizole, cisapride, pimozide, or carbamazepine hypersensitivity to other phenylpiperazine antidepressants those who were withdrawn from nefazodone due to evidence of hepatic injury use within 14 days of MAOIs... 

Nefazodone is a weak inhibitor of CYP2D6 but a potent inhibitor of CYP3A4 and it increases plasma concentrations of drugs that are substrates of CYP3A4, such as alprazolam, astemizole, carbamazepine, ciclosporin, cisapride, terfenadine, and triazolam. 

Clinically important, potentially hazardous interactions with alprazolam, astemizole, carbamazepine, cisapride, clarithromycin, dexamethasone, diltiazem, docetaxel, ifosfamide, imatinib, irinotecan, itraconazole, ketoconazole, methylprednisolone, midazolam, nefazodone, oral contraceptives, paroxetine, phenytoin, pimozide, rifampin, ritonavir, terfenadine, tolbutamide, trabectedin, troleandomycin, vinblastine, vincristine, warfarin... 

Clinically important, potentially hazardous interactions with amphetamines, aprepitant, astemizole, atazanavir, azithromycin, azole antifungals, clarithromycin, darunavir, dirithromycin, erythromycin, fluoxetine, fosamprenavir, grapefruit juice, imatinib, indinavir, itraconazole, ketoconazole, methylphenidate, nefazodone, nelfinavir, nilotinib, pemoline, phenothiazines, protease inhibitors, quinidine, ritonavir, saquinavir, sertraline, sparfloxacin, sulpiride, telithromycin, thioridazine, tipranavir, tricyclic antidepressants, troleandomycin, voriconazole, zileuton, ziprasidone... 

Nefazodone inhibits the metabolism of terfenadine and thereby prolongs the QT interval. This combination should be avoided. There is also some evidence that the combination of nefazodone and loratadine increases the QT interval, although to a lesser extent than terfenadine. In vitro evidence suggests nefazodone will also inhibit the metabolism of astemizole. 

The manufacturers of nefazodone and astemizole say that an in vitro study suggests that nefazodone may increase astemizole levels, and so concur-... 

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