Coadministration with emtricitabine/tenofovir-DF has not been studied. Based on metabolism and elimination a clinically significant interaction with emtricitabine is unlikely. No clinically significant pharmacokinetic interaction was observed between tenofovir-DF and dolutegravir. Coadministration of tenofovir-DF (300 mg once daily) and dolutegravir (50 mg once daily) decreased dolutegravir Cmax and Ctrough by 3% and 8%, and increased AUC by 1%. Tenofovir Cmax, AUC and Ctrough increased by 9%, 12% and 19%, respectively. Coadministration with emtricitabine has not been studied but based on metabolism and elimination no clinically significant interaction is likely. No dosage adjustment is necessary.

Coadministration has not been studied but based on metabolism and clearance a clinically significant interaction is unlikely. Dexamethasone is metabolized by CYP3A4. Dexamethasone and its metabolites are excreted in the urine.

Coadministration has not been studied. Dexamethasone is metabolized by CYP3A4. Dolutegravir is primarily metabolized by UGT1A1, with some contribution from CYP3A. Dolutegravir has no inhibitory or inducing effects on drug metabolizing enzymes. Dexamethasone is a weak CYP3A4 inducer at a low dose and is unlikely to have a clinically significant effect on dolutegravir.