The FDA has approved Odefsey (Gilead), a once-daily, fixed-dose combination of the non-nucleoside reverse transcriptase inhibitor (NNRTI) rilpivirine and the nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) emtricitabine and tenofovir alafenamide, for initial treatment of HIV-1 infection in patients with HIV-1 RNA (viral load) ≤100,000 copies/mL or to replace a stable antiretroviral regimen in patients who have been virologically suppressed (viral load <50 copies/mL) for at least six months with no history of treatment failure.

The FDA has approved a fixed-dose combination of the integrase strand transfer inhibitor (INSTI) elvitegravir, the pharmacokinetic enhancer cobicistat, and the nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) emtricitabine and tenofovir disoproxil fumarate (Stribild – Gilead) for treatment of HIV-1 infection in antiretroviral treament-naïve adults. Elvitegravir is the second INSTI to be approved by the FDA for use in HIV treatment; raltegravir (Isentress) was the first.

Etravirine (Intelence - Tibotec), a new non-nucleoside reverse transcriptase inhibitor (NNRTI), has received fast-track FDA approval for use in combination therapy in treatment-experienced adults who have HIV-1 infection resistant to an NNRTI and other antiretroviral agents.

The FDA has approved emtricitabine/tenofovir (Truvada - Gilead) and abacavir/lamivudine (Epzicom - GSK), two new fixed-dose combinations of nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), for once-daily use in treatment of HIV infection. Two other fixed-dose NRTI combinations were previously approved for twice-daily dosing. Dual NRTI therapy is generally used in either an NNRTI (non-nucleoside reverse transcriptase inhibitor)-based or a PI (protease inhibitor)-based regimen.

Serious adverse interactions between drugs continue to be reported. Many of these are due to inhibition or induction of cytochrome P450 (CYP) enzymes, particularly CYP3A4. CYP3A is thought to be involved in the metabolism of more than 50 percent of currently prescribed drugs.2 CYP3A4, which is more abundantly expressed than CYP3A5, accounts for most CYP3A activity in vivo.

Valoctocogene roxaparvovec-rvox (Roctavian – Biomarin), an adeno-associated virus (AAV) vector-based gene therapy, has been approved by the FDA for one-time treatment of severe hemophilia A in adults without pre-existing antibodies to AAV serotype 5. It is the first gene therapy to be approved in the US for treatment of hemophilia A.

View Table 3: Some Drug Interactions with DAAs for HCV Infection

Amprenavir is the fifth protease inhibitor to become available for treatment of HIV infection. It was approved by the FDA for use with other drugs in the treatment of HIV-infected adults and children at least four years old.

The FDA has approved Zepatier (Merck), a fixed-dose combination of two direct-acting antiviral agents — elbasvir, an NS5A inhibitor, and grazoprevir, an NS3/4A protease inhibitor — for oral treatment of chronic hepatitis C virus (HCV) genotype 1 or 4 infection.

Darunavir (Prezista - Tibotec), a new protease inhibitor, has received accelerated approval from the FDA for use in combination therapy of human-immunodeficiency virus (HIV) infection in previously treated adults. It is coadministered with low-dose ritonavir (Norvir), which increases its bioavailability.