Coadministration has not been studied. Dexamethasone is metabolized by CYP3A4. Rilpivirine is primarily metabolized by CYP3A4 and has no inhibitory or inducing effects on drug metabolizing enzymes. Cabotegravir is mainly metabolized by UGT1A1 and to a lesser extent by UGT1A9. Dexamethasone is a weak CYP3A4 inducer at a low dose and may decrease rilpivirine concentrations, although to a small extent since intramuscular administration bypasses intestinal metabolism. It should be noted that rilpivirine trough concentration is expected to be lowest after the first intramuscular injection. While the magnitude of the interaction with dexamethasone is expected to be small, the possibility of an interaction resulting in suboptimal exposure in some individuals who initiate IM rilpivirine without an oral lead-in cannot be ruled out. Therefore, it is advisable to avoid initiation of rilpivirine/cabotegravir IM during and for 2 weeks post dexamethasone treatment. Consider adding oral rilpivirine 25 mg once daily to rilpivirine/cabotegravir IM during treatment with dexamethasone in individuals who have just started rilpivirine/cabotegravir IM. In the specific case of patients being treated with short term dexamethasone for COVID-19 please refer to www.covid19-druginteractions.org for additional advice.