Terfenadine Aprepitant

Clinically important, potentially hazardous interactions with alfuzosin, alprazolam, amphotericin B, anisindione, antacids, aprepitant, astemizole, atorvastatin, bosentan, ciclesonide, cimetidine, clorazepate, conivaptan, cyproterone, dasatinib, dexamethasone, dicumarol, didanosine, eplerenone, erythromycin, ethotoin, fentanyl, fesoterodine, fosamprenavir, fosphenytoin, grapefruit juice, HMG-CoA reductase inhibitors, imatinib, ixabepilone, lapatinib, lopinavir, lovastatin, mephenytoin, methylprednisolone, micafungin, midazolam, nilotinib, pimozide, prednisolone, prednisone, quinidine, rifampin, rimonabant, rivaroxaban, sildenafil, silodosin, simvastatin, sirolimus, solifenacin, temsirolimus, terfenadine, tolvaptan, triazolam, vardenafil, vinblastine, vincristine, warfarin... 

Clinically important, potentially hazardous interactions with aprepitant, astemizole, carbamazepine, colchicine, cyclosporine, dihydroergotamine, ergot alkaloids, ergotamine, erythromycin, fluoxetine, fluvoxamine, methylprednisolone, methysergide, oral contraceptives, paroxetine, pimozide, prednisolone, rifampicin, sertraline, solifenacin, terfenadine, warfarin... 

Aprepitant can increase the levels of CYP3A4 substrates in the short-term, then reduce them within 2 weeks. Caution is advised. Note that the manufacturers of aprepitant specifically contraindicate its concurrent use with pimozide, terfenadine, astemizole or cisapride. 

Absolute aprepitant is contraindicated in patients who are hypersensitive to any component of the product. Aprepitant is a weak-to-moderate (dose-dependent) cytochrome P450 isoenzyme 3A4 (CYP3A4) inhibitor. Aprepitant should not be used concurrently with pimozide, terfenadine, astemizole, or cisapride. Dose-dependent inhibition of CYP3A4 by aprepitant could result in elevated plasma concentrations of these drugs, potentially causing serious or life-threatening ventricular arrhythmias. 

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