Telzir må ikke administreres samtidig med præparater, som har smalt terapeutisk vindue, og som er substrater for cytokrom P450 3A4 (CYP3A4), f. eks. amiodaron, astemizol, bepridil, cisaprid,
Telzir must not be administered concurrently with medicinal products with narrow therapeutic windows that are substrates of cytochrome P450 3A4 (CYP3A4), e. g. amiodarone, astemizole, bepridil, cisapride, dihydroergotamine, ergotamine, pimozide, quinidine, terfenadine, oral midazolam (for caution on parenterally administered midazolam, see section 4.5), oral triazolam.