Coadministration has not been studied, but based on metabolism and clearance a pharmacokinetic interaction is unlikely. Levomepromazine is metabolised by CYP2D6. Cabotegravir and rilpivirine do not inhibit or induce CYP enzymes at clinically relevant concentrations. Rilpivirine has been associated with prolongation of the QTc interval at supra-therapeutic doses but these are unlikely to occur when coadministered with levomepromazine. However, given the known QT prolongation risk associated with levomepromazine, caution is recommended