Coadministration with intramuscular cabotegravir and rilpivirine has not been studied but based on metabolism and clearance a clinically significant interaction is unlikely. Sildenafil is metabolized by CYP3A4. Cabotegravir was shown to have no effect on midazolam (a sensitive CYP3A4 substrate) in healthy subjects. Coadministration of oral rilpivirine (75 mg once daily) and a single dose of sildenafil (50 mg, as used for the treatment of erectile dysfunction) decreased rilpivirine Cmax and AUC by 8% and 2%, and increased Cmin by 4%. Sildenafil Cmax and AUC decreased by 7% and 3%; N-desmethyl sildenafil Cmax and AUC decreased by 10% and 8%, respectively.