Bictegravir

This single dose medication inhibits the strand transfer of viral DNA into the human genome, preventing HIV-1 virus replication and propagation.

In vitro, bictegravir has shown powerful antiviral activity against HIV-2 and various subtypes of HIV-1. It has shown synergistic effects when combined with other ARVs, including tenofovir alafenamide (TAF), emtricitabine (FTC), and darunavir (DRV). The three components of the first USA approved medication ( trade name: Biktarvy) are as follows:

Bictegravir: integrase strand transfer inhibitor; INSTI), an HIV-1 encoded enzyme necessary for viral replication. Inhibition of the integrase enzyme prevents the integration of HIV-1 into host DNA, blocking the conversion of the HIV-1 provirus and progression of the virus.

Emtricitabine: FTC, is phosphorylated by cellular enzymes to form emtricitabine 5'-triphosphate. Emtricitabine is phosphorylated to form emtricitabine 5'-triphosphate intracellularly. This metabolite inhibits the activity of human immunodeficiency virus (HIV) reverse transcriptase by competing with the substrate deoxycytidine 5'-triphosphate and by incorporating itself into viral DNA preventing DNA chain elongation.

Tenofovir Alafenamide: TAF is a phosphonamidate prodrug of tenofovir (2′-deoxyadenosine monophosphate analog). Plasma exposure to TAF leads to leakage into cells and then TAF is intracellularly converted to tenofovir by hydrolysis by cathepsin. Tenofovir is subsequently phosphorylated by cellular kinases to the metabolite tenofovir diphosphate, which is the active form of the drug. Tenofovir diphosphate inhibits HIV-1 replication by incorporating into viral DNA by the HIV reverse transcriptase, resulting in DNA chain-termination. Tenofovir diphosphate also weakly inhibits mammalian DNA polymerases.