Moroxydine is an antiviral drug discovered in the 1950’s which was shown to be active against DNA and RNA viruses. Moroxydine analogues are potent anti-hepatitis C virus (HCV) agents.

Favipiravir (originally known as T-705) is an orally administered novel anti-viral compound with a unique mechanism of action that is active against a wide range of RNA-based viruses in laboratory tests. Favipiravir has recently being approved in Japan under the brand name Avigan. Avigan is an experimental antiviral drug being developed by Toyama Chemical of Japan. It is a viral RNA polymerase inhibitor with a new mechanism of action, inhibiting viral gene replication within infected cells to prevent the propagation. Favipiravir is phosphoribosylated by cellular enzymes to its active form, favipiravir-ribofuranosyl-5′- triphosphate (RTP). Favipiravir is active against a broad range of influenza viruses, including A(H1N1)pdm09, A(H5N1) and the recently emerged A(H7N9) avian virus. It also inhibits influenza strains resistant to current antiviral drugs, and shows a synergistic effect in combination with oseltamivir, thereby expanding influenza treatment options. A Phase III clinical evaluation of favipiravir for influenza therapy has been completed in Japan and two Phase II studies have been completed in the United States. In addition to its anti-influenza activity, favipiravir blocks the replication of many other RNA viruses, including arenaviruses (Junin, Machupo and Pichinde); phleboviruses (Rift Valley fever, sandfly fever and Punta Toro); hantaviruses (Maporal, Dobrava, and Prospect Hill); flaviviruses (yellow fever and West Nile); enteroviruses (polio- and rhinoviruses); an alphavirus, Western equine encephalitis virus; a paramyxovirus, respiratory syncytial virus; and noroviruses.

Buciclovir is an acyclic guanosine analog with activity against herpes simplex virus (HSV). Buciclovir is phosphorylated to its triphosphate form by HSV thymidine kinase in infected cells and acts as a specific inhibitor of the viral DNA polymerase. Buciclovir inhibited DNA synthesis, not RNA synthesis, and prevented an increase in the size of newly synthesized DNA. Topical treatment initiated early after infection was efficacious, in contrast to topical treatment delayed 24 h or more. Systemic treatment of infected mice could not prevent the spread of the virus to the brain and mortality. Systemically administered buciclovir had an effect in guinea pigs, even after the delayed onset of treatment, but this effect required high doses of the drug. Buciclovir has only a limited effect against herpesvirus infections once the virus is present in the nervous systems of infected

5-iodo-2'-deoxycytidine (IBACITABINE) is an anti-herpetic agent. Experiments with a tumor mouse model have revealed, that radioiodinated compound, (131)I-5-iodo-2'-deoxycytidine was a promising single photon emission computed tomography probe for imaging proliferation.

Brivudine (trade names Zostex, Mevir, Brivir, among others) is an antiviral drug used in the treatment of herpes zoster ("shingles"). Brivudine is an analog of the nucleoside thymidine. The active compound is brivudine 5'-triphosphate, which is formed in subsequent phosphorylations by viral (but not human) thymidine kinase and presumably by the nucleoside-diphosphate kinase. Brivudine 5'-triphosphate works because it is incorporated into the viral DNA, but then blocks the action of DNA polymerases, thus inhibiting viral replication. Brivudine is used for the treatment of herpes zoster in adult patients. It is taken orally once daily, in contrast to aciclovir, valaciclovir, and other antivirals. A study has found that it is more effective than aciclovir, but this has been disputed because of a possible conflict of interest on part of the study authors. The drug is contraindicated in patients undergoing immunosuppression (for example because of an organ transplant) or cancer therapy, especially with fluorouracil (5-FU) and chemically related (pro)drugs such as capecitabine and tegafur, as well as the antimycotic drug flucytosine, which is also related to 5-FU. It has not been proven to be safe for children and pregnant or breastfeeding women. The drug is generally well tolerated. The only common side effect is nausea (in 2% of patients). Less common side effects (<1%) include a headache, increased or lowered blood cell counts (granulocytopenia, anemia, lymphocytosis, monocytosis), increased liver enzymes, and allergic reactions. Brivudine is approved for use in a number of European countries including Austria, Belgium, Germany, Greece, Italy, Portugal, Spain, and Switzerland.

Umifenovir or arbidol (ethyl-6-bromo-4-[(dimethylamino)methyl]-5-hydroxy-1-methyl-2-[(phenylthio)methyl]-indole-3-carboxylate hydrochloride monohydrate) is a Russian-made potent broad-spectrum antiviral with demonstrated activity against a number of enveloped and non-enveloped viruses.For both viral infections the anti-viral mechanism involves umifenovir inhibition of virus-mediated fusion with target membrane and a resulting block of virus entry into target cells. Arbidol was shown to have effects on nonspecific defense factors, on its capacity to induce interferon and activate phagocytes in particular. Arbidol-treated patients with lower baseline immunity showed improvement in immunological parameters (in the counts of CD4 and CD8 lymphocytes, B lymphocytes, in the levels of serum immunoglobulins). Arbidol produces a high preventive and therapeutical effects in influenza A and B and other acute respiratory viral infections, prevents postinfluenza complications, reduces the incidence of exacerbations of chronic diseases in postinfluenza patients. In influenza, the therapeutical efficiency of the drug appears as decreases in intoxication, the severity of catarrhal syndrome, shorter fever and disease in general. Arbidol is beneficial for patients with secondary immunodeficiency, in those with recurrent herpes infection or chronic bronchitis.

SORIVUDINE (BV-araU) is an Anti-Herpes Virus Drugs, which was Withdrawn in 1995. Aantiviral action of BV-araU against VZV (varicella-zoster virus) and herpes simplex virus type 1 (HSV-1) is based on the inhibition of DNA synthesis in herpesvirus-infected cells.

Ingavirin is pentanedioic acid imidazolyl ethanamide used for the treatment of Influenza and Common Cold in Russia and some other countries. The mechanism of action is implemented at the level of infected cells due to the stimulation of innate immunity factors suppressed by viral proteins. The drug causes an increase in the content of interferon in the blood to the physiological norm, stimulates and normalizes the reduced α-interferon-producing ability of blood leukocytes, stimulates the γ-interferon-producing ability of leukocytes.

Enisamium (4-(benzylcarbamoyl)-1-methylpyridinium iodide) is an isonicotinic acid derivative, that used as an antiviral agent in Russia. Enisamium suppresses the effect of influenza viruses and other pathogens of acute respiratory viral infections due to a direct inhibitory effect on the penetration of viruses through the cell membrane. Enisamium has interferonogenic properties, promotes an increase in the concentration of endogenous interferon (interferon alfa and gamma) in blood plasma by 3-4 times.

Dapivirine, an anti-retroviral (ARV)-based microbicide, is a substituted diaminopyrimidine (DAPY) derivative and a potent non-nucleoside reverse-transcriptase inhibitor (NNRTI) with antiviral activity against HIV-1. Dapivirine showed high activity against wild-type and mutant HIV in in virto HIV models inhibiting a broad panel of HIV-1 isolates from different classes, including a wide range of NNRTI-resistant isolates. Developed by Janssen Sciences (formerly Tibotec Pharmaceuticals), dapivirine was initially tested as an oral treatment for HIV in a number of Phase I/II clinical trials. In 2014 the International Partnership for Microbicides (IPM) began its work on the monthly dapivirine ring. Phase I/II clinical trials in Africa, Europe and the United States proved that dapivirine is safe and well-tolerated. Phase III long-term safety and efficacy studies of the monthly dapivirine ring as part of IPM's Dapivirine Ring Licensure Program confirmed that the monthly dapivirine ring can safely help prevent HIV infection in women. In 2016 the ASPIRE Study reported a 27 percent reduction in HIV-1 acquisition with a trend toward greater protection in women over age 21 and no significant protection for women under age 21.