ATC Group: J05AB Nucleosides and nucleotides excl. reverse transcriptase inhibitors

Acyclovir is an antiviral agent with activity against herpes simplex virus and varicella-zoster virus. Acyclovir inhibits the DNA polymerase of the virus, preventing further proliferation.

Brivudine is a thymidine analogue with antiviral activity, indicated for the early treatment of acute herpes zoster in adult patients. Brivudine is incorporated into the viral DNA and blocks the action of DNA polymerases, thus inhibiting viral replication.

Cidofovir suppresses HCMV replication by selective inhibition of viral DNA synthesis. Biochemical data support selective inhibition of HSV-1, HSV-2 and HCMV DNA polymerases by cidofovir diphosphate, the active intracellular metabolite of cidofovir.

Famciclovir is the oral prodrug of penciclovir. Famciclovir is rapidly converted in vivo into penciclovir, which has in vitro activity against herpes simplex viruses (HSV types 1 and 2), varicella zoster virus (VZV), Epstein-Barr virus and cytomegalovirus.

Ganciclovir, 9-(1,3-dihydroxy-2-propoxymethyl)guanine or DHPG, is a broadspectrum virustatic agent which inhibits the replication of viruses, including viruses of the herpes group, both in vivo and in vitro: herpes simplex types 1 and 2 (HSV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes zoster (HZV).

Molnupiravir is indicated for treatment of mild to moderate coronavirus disease 2019 (COVID-19) in adults with a positive SARS-COV-2 diagnostic test and who have at least one risk factor for developing severe illness. Molnupiravir is a prodrug that is metabolised to the ribonucleoside analogue N-hydroxycytidine (NHC) which distributes into cells where it is phosphorylated to form the pharmacologically active ribonucleoside triphosphate (NHC-TP).

Penciclovir has demonstrated in vivo and in vitro activity against herpes simplex viruses (types 1 and 2) and varicella zoster virus. Penciclovir triphosphate persists in infected cells for more than 12 hours where it inhibits replication of viral DNA and has a half-life of 9, 10 and 20 hours in cells infected with varicella zoster virus, herpes simplex virus type 1 and herpes simplex virus type 2 respectively.

Valaciclovir, an antiviral, is the L-valine ester of aciclovir. Valaciclovir is rapidly and almost completely converted in man to aciclovir and valine. Aciclovir is a specific inhibitor of the herpes viruses with in vitro activity against herpes simplex viruses (HSV) type 1 and type 2, varicella zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr Virus (EBV), and human herpes virus 6 (HHV-6).

Valganciclovir is an L-valyl ester (prodrug) of ganciclovir. Ganciclovir is a synthetic analogue of 2'-deoxyguanosine and inhibits replication of herpes viruses in vitro and in vivo.