26 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.