Emtricitabine/tenofovir-DF should not be administered with additional emtricitabine or with tenofovir alafenamide.

Coadministration has not been studied. Valaciclovir is converted to aciclovir which is eliminated renally via glomerular filtration and active renal secretion by OAT1. Based on metabolism and clearance a clinically significant interaction between emtricitabine and valaciclovir is unlikely. Since tenofovir is primarily eliminated by the kidneys, coadministration with drugs that reduce renal function or compete for active tubular secretion may increase concentrations of tenofovir or the coadministered drug. Tenofovir-DF should be avoided with concurrent or recent use of a nephrotoxic agent. If concomitant use of tenofovir-DF and nephrotoxic agents is unavoidable, renal function should be monitored closely.

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. Doravirine is metabolized by CYP3A4. Emtricitabine and tenofovir alafenamide do not interfere with CYP450 mediated metabolism.

Coadministration has not been studied but based on metabolism and clearance a clinically significant interaction is unlikely. Doravirine is metabolized by CYP3A4. Emtricitabine and tenofovir-DF do not interfere with CYP450 mediated metabolism.

Coadministration has not been studied but based on metabolism and clearance a clinically significant interaction is unlikely. Valaciclovir is converted to aciclovir which is eliminated renally via glomerular filtration and active renal secretion by OAT1. Emtricitabine and tenofovir alafenamide are unlikely to compete with aciclovir for renal transporters as emtricitabine is eliminated by different renal transporters and tenofovir alafenamide results in 90% lower systemic levels of tenofovir compared to tenofovir-DF. Dose Descovy according to the concomitant antiretroviral. 

Coadministration of dolutegravir (50 mg once daily) with emtricitabine/tenofovir alafenamide (200/10 mg, once daily) increased tenofovir AUC and Cmax by 25% and 10% (n=10). No significant effects were observed on dolutegravir pharmacokinetics relative to historical controls. Coadministration of dolutegravir (50 mg once daily) and tenofovir alafenamide/emtricitabine/elvitegravir/cobicistat (10/200/150/150 mg) had no significant effect on the pharmacokinetics of dolutegravir and tenofovir alafenamide. The recommended dose of Descovy for HIV-1 treatment is 200/25 mg once daily.