Contraindicated w/ terfenadine, astemizole, mizolastine; bepridil; nisoldipine; cisapride; midazolam (oral), triazolam; lovastatin, simvastatin, atorvastatin; pimozide, sertindole; levacetylmethadol; dihydroergotamine, ergotamine, eletriptan; ergometrine (ergonovine), methylergometrine (methylergonovine); quinidine, dofetilide. Do not use Itrazol oral soln w/in 2 wk of taking rifampicin, rifabutin, isoniazid; phenytoin, carbamazepine, phenobarb; St. John's wort. Dose adjustments may be needed w/ clarithromycin, erythromycin; digoxin, disopyramide, Ca channel-blockers eg, dihydropyridines, verapamil, cilostazol; anticoagulants eg, warfarin; methylprednisolone, budesonide, fluticasone, dexamethasone; ciclosporin, tacrolimus, rapamycin (sirolimus); anti-HIV eg, ritonavir, indinavir, saquinavir; anti-cancer eg, busulphan, docetaxel, trimetrexate, vinca alkaloids; alfentanil, fentanyl; buspirone, alprazolam, brotizolam, midazolam (inj); reboxetine; loperamide; ebastine; halofantrine; repaglinide.