Macrolides
Erythromycin is a known CYP3A4 inhibitor . A clinically relevant interaction is possible with co-administration of erythromycin and LAI cabotegravir/rilpivirine due to potentially increased levels of rilpivirine, a CYP3A4 substrate. High steady-state Cmaxof oral rilpivirine (4.4-fold higher than that observed (116 ng/mL) with the recommended 600 mg monthly dose of injectable rilpivirine) has been associated with prolongation of the cardiac repolarization cycle (QT interval) . A further risk for QT prolongation, resulting from a potential pharmacodynamic interaction, is the fact that macrolides are also associated with a QT prolonging effect . Prolongation of the QT interval is a risk factor for development of ventricular arrhythmias, particularly torsade de pointes, a rare but life-threatening event. Caution should, therefore, be exercised with co-administration of older macrolides and LAI cabotegravir/rilpivirine. Azithromycin may be considered as an alternative due to its low propensity for CYP3A4 inhibition and can be safely co-administered with cabotegravir and rilpivirine .