Coadministration has not been studied but based on metabolism and clearance a pharmacokinetic interaction is unlikely. Ivabradine is metabolized by CYP3A4. Fostemsavir is a prodrug and is hydrolysed to the active compound temsavir in the small intestine. Temsavir is mainly metabolized by esterase-mediated hydrolysis with a small contribution of CYP3A4. Temsavir does not inhibit or induce CYP enzymes. Fostemsavir has been associated with prolongation of the QTc interval at supra-therapeutic doses but equivalent fostemsavir concentrations are unlikely to occur during coadministration with ivabradine. However, the product labels for fostemsavir indicate that fostemsavir should be used with caution in combination with drugs with a known risk of Torsade de Pointes. Ivabradine has a known risk of QT prolongation and/or TdP on the CredibleMeds.org website. The use of ivabradine in patients treated with QT prolonging medicinal products should be avoided. If the combination appears necessary, close cardiac monitoring is needed.