Antiviral Agents

The antivirals are a large and diverse group of agents that are typically classified by the virus infections for which they are used, their chemical structure and their mode of action. Most antiviral agents have been developed in the last 20 to 25 years, many as a result of the major research efforts to develop therapies and means of prevention of human immunodeficiency virus (HIV) infection and the acquired immunodeficiency syndrome (AIDS). Some of the agents developed to treat HIV infection, AIDS and its complications were found to also inhibit other viruses, and the novel approaches taken in development of antiretroviral therapy have been applied to develop therapies of other viral infections. . The antiretroviral agents include nucleoside analogues with reverse transcriptase activity (such as tenofovir, emtricitabine, lamivudine, abacavir, stavudine, didanosine, zidovudine), the nonnucleoside reverse transcriptase inhibitors (such as delavirdine, efavirenz, etravirine, nevirapine and rilpivirine), protease inhibitors (atazanavir, darunavir, indinavir, ritonavir, tipranavir and many others), and miscellaneous agents such as maraviroc that inhibits binding of the HIV virus its T cell receptor (CCR5 coreceptor antagonist), enfuvirtide that blocks the uptake of HIV into cells (fusion inhibitor), and integrase inhibitors (raltegravir, elvitegravir and dolutegravir) that block the integrase enzyme of HIV. . The agents active against hepatitis B virus (HBV) include several nucleoside analogues that are also active against and used to treat HIV infection (tenofovir, emtricitabine, lamivudine), as well as agents that are poorly if at all active against HIV (adefovir, entecavir and telbivudine). Alpha interferon and peginterferon (its long acting pegylated form) are also active against hepatitis B, but are no longer commonly used for this indication.