Elvitegravir is a human immunodeficiency virus type 1 (HIV-1) integrase strand transfer inhibitor used in combination with cobicistat, emtricitabine and tenofovir alafenamid (GENVOYA®) for the treatment of HIV-1 infection in antiretroviral treatment-experienced adults. Because integrase is necessary for viral replication, inhibition prevents the integration of HIV-1 DNA into the host genome and thereby blocks the formation of the HIV-1 provirus and resulting propagation of the viral infection.

Rilpivirine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) which is used for the treatment of HIV-1 infections in treatment-naive patients. It is active against wild-type and NNRTI-resistant HIV-1. Rilpivirine is a diarylpyrimidinethat inhibits HIV-1 replication by non-competitive inhibition of HIV-1 reverse transcriptase (RT). Rilpivirine does not inhibit the human cellular DNA polymerases α, β and γ.

Etravirine (formerly known as TMC125) is an antiretroviral agent more specifically classified as a Non-Nucleoside Reverse Transcriptase Inhibitor. Etravirine exerts its effects via direct inhibition of the reverse transcriptase enzyme of human immunodeficiency virus type 1 (HIV-1). It directly binds reverse transcriptase and consequently blocks DNA-dependent and RNA-dependent polymerase activity. In combination with other antiretroviral agents, it is indicated for the treatment of human immunodeficiency virus type 1 (HIV-1) infection in antiretroviral treatment-experienced adult patients, who have evidence of viral replication and HIV-1 strains resistant to a non-nucleoside reverse transcriptase inhibitor (NNRTI) and other antiretroviral agents. The most common adverse events (incidence > 10%) of any intensity that occurred at a higher rate than placebo are rash and nausea. Etravirine should not be co-administered with the following antiretrovirals: Tipranavir/ritonavir, fosamprenavir/ritonavir, atazanavir/ritonavir; Protease inhibitors administered without ritonavir; NNRTIs.

Maraviroc (UK-427,857; brand-named Selzentry, or Celsentri outside the U.S) is a selective CCR5 antagonist with potent anti-human immunodeficiency virus type 1 (HIV-1) activity and favorable pharmacological properties. Maraviroc is the product of a medicinal chemistry effort initiated following identification of an imidazopyridine CCR5 ligand from a high-throughput screen of the Pfizer compound file. Selzentry, in combination with other antiretroviral agents, is indicated for adult patients infected with only CCR5-tropic HIV-1. This indication is based on analyses of plasma HIV-1 RNA levels in two controlled trials of SELZENTRY in treatment-experienced subjects and one trial in treatment-naive subjects. Maraviroc selectively binds to the human chemokine receptor CCR5 present on the cell membrane, preventing the interaction of HIV-1 gp120 and CCR5 necessary for CCR5-tropic HIV-1 to enter cells. CXCR4-tropic and dual-tropic HIV-1 entry is not inhibited by maraviroc. Antiviral Activity in Cell Culture Maraviroc inhibits the replication of CCR5-tropic laboratory strains and primary isolates of HIV-1 in models of acute peripheral blood leukocyte infection. The mean EC50 value (50% effective concentration) for maraviroc against HIV-1 group M isolates (subtypes A to J and circulating recombinant form AE) and group O isolates ranged from 0.1 to 4.5 nM (0.05 to 2.3 ng per mL) in cell culture. When used with other antiretroviral agents in cell culture, the combination of maraviroc was not antagonistic with NNRTIs (delavirdine, efavirenz, and nevirapine), NRTIs (abacavir, didanosine, emtricitabine, lamivudine, stavudine, tenofovir, zalcitabine, and zidovudine), or protease inhibitors (amprenavir, atazanavir, darunavir, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir, and tipranavir). Maraviroc was not antagonistic with the HIV fusion inhibitor enfuvirtide. Maraviroc was not active against CXCR4-tropic and dual-tropic viruses (EC50 value greater than 10 µM). The antiviral activity of maraviroc against HIV-2 has not been evaluated. Maraviroc can cause serious, life-threatening side effects such as, liver problems, skin reactions, and allergic reactions.

Raltegravir (RAL, Isentress, formerly MK-0518) is an antiretroviral drug produced by Merck & Co., used to treat HIV and it is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection in patients 4 weeks of age and older. Raltegravir inhibits the catalytic activity of HIV-1 integrase, an HIV-1 encoded enzyme that is required r viral replication. Inhibition of integrase prevents the covalent insertion, or integration, of unintegrated linear HIV-1 DNA into the host cell genome preventing the formation of the HIV-1 provirus. The provirus is required to direct the production of progeny virus, so inhibiting integration prevents propagation of the viral infection. Raltegravir did not significantly inhibit human phosphoryl transferases including DNA polymerases α, β, and γ. Coadministration with others drugs that are strong inducers of UGT1A1, such as rifampin, may result in reduced plasma concentrations of raltegravir. The most common adverse reactions of moderate to severe intensity (≥2%) are insomnia, headache, dizziness, nausea and fatigue. Severe, potentially life-threatening, and fatal skin reactions have been reported. This include cases of Stevens-Johnson syndrome and toxic epidermal necrolysis. Hypersensitivity reactions have also been reported and were characterized by rash, constitutional findings, and sometimes, organ dysfunction, including hepatic failure. The major mechanism of clearance of raltegravir in humans is UGT1A1-mediated glucuronidation.

Tipranavir (PNU-140690, trade mark APTIVUS) is a potent, orally bioavailable nonpeptidic HIV protease inhibitor of the 5,6-dihydro-4-hydroxy-2-pyrone sulfonamide class. Tipranavir has potent in vitro activity against a variety of HIV-1 laboratory strains and clinical isolates, including those resistant to ritonavir, as well as HIV-2. The drug is launched in several countries, including the US and in the EU. APTIVUS, co-administered with ritonavir, is indicated for combination antiretroviral treatment of HIV-1 infected patients who are treatment-experienced and infected with HIV-1 strains resistant to more than one protease inhibitor.

BARACLUDE® is the tradename for entecavir, a guanosine nucleoside analogue with selective activity against hepatitis B virus (HBV). It inhibits all three steps in the viral replication process. By competing with the natural substrate deoxyguanosine triphosphate, entecavir functionally inhibits all three activities of the HBV polymerase (reverse transcriptase, rt): (1) base priming, (2) reverse transcription of the negative strand from the pregenomic messenger RNA, and (3) synthesis of the positive strand of HBV DNA. Upon activation by kinases, the drug can be incorporated into the DNA which has the ultimate effect of inhibiting the HBV polymerase activity. Entecavir is used for the treatment of chronic hepatitis B virus infection in adults with evidence of active viral replication and either evidence of persistent elevations in serum aminotransferases (ALT or AST) or histologically active disease.

Atazanavir is the first once-daily protease inhibitor for the treatment of human immunodeficiency virus type 1 infection and should be used only in combination therapy, as part of a highly active antiretroviral therapy (HAART) regimen. In addition to being the most potent protease inhibitor in vitro, atazanavir has a distinct cross-resistance profile that does not confer resistance to other protease inhibitors. However, resistance to other protease inhibitors often confers clinically relevant resistance to atazanavir.

Emtricitabine was discovered by Emory researchers Dr. Dennis C. Liotta, Dr. Raymond F. Schinazi and Dr. Woo-Baeg Choi and licensed to Triangle Pharmaceuticals by Emory University in 1996. Triangle was acquired by Gilead in 2003. Emtricitabine, marketed by Gilead as Emtriva, was first approved by the U.S. Food and Drug Administration in July 2003 for the treatment of HIV infection in combination with other antiretroviral agents. Emtricitabine, a synthetic nucleoside analog of cytidine, is phosphorylated by cellular enzymes to form emtricitabine 5'-triphosphate. Emtricitabine 5'-triphosphate inhibits the activity of the HIV-1 reverse transcriptase by competing with the natural substrate deoxycytidine 5'-triphosphate and by being incorporated into nascent viral DNA which results in chain termination.

The potential antiviral effect of adefovir, an acyclic nucleoside phosphonate analog of 2′-deoxyadenosine monophosphate, was first studied by Holý and De Clercq in 1980s. Adefovir is an acyclic nucleotide analog of adenosine monophosphate which is phosphorylated to the active metabolite adefovir diphosphate by cellular kinases. Adefovir diphosphate inhibits HBV DNA polymerase (reverse transcriptase) by competing with the natural substrate deoxyadenosine triphosphate and by causing DNA chain termination after its incorporation into viral DNA. Oral adefovir dipivoxil is effective and generally well tolerated in HBeAg-positive and -negative patients chronically infected with wild-type or lamivudine-resistant HBV.