Aciclovir, also known as acyclovir, is an antiviral medication. It is primarily used for the treatment of herpes simplex virus infections, chickenpox, and shingles. Other uses include prevention of cytomegalovirus infections following transplant and severe complications of Epstein–Barr virus infection. It can be taken by mouth, applied as a cream, or injected.
Ritonavir, sold under the brand name Norvir, is an antiretroviral medication used along with other medications to treat HIV/AIDS. This combination treatment is known as highly active antiretroviral therapy (HAART). Ritonavir is a protease inhibitor, though it now mainly serves to boost the potency of other protease inhibitors. It may also be used in combination with other medications to treat hepatitis C and COVID-19. It is taken by mouth. Tablets of ritonavir are not bioequivalent to capsules, as the tablets may result in higher peak plasma concentrations.
A prodrug is a pharmacologically inactive medication or compound that, after intake, is metabolized into a pharmacologically active drug. Instead of administering a drug directly, a corresponding prodrug can be used to improve how the drug is absorbed, distributed, metabolized, and excreted (ADME).
The first pass effect is a phenomenon of drug metabolism at a specific location in the body which leads to a reduction in the concentration of the active drug before it reaches the site of action or systemic circulation. The effect is most associated with orally administered medications, but some drugs still undergo first-pass metabolism even when delivered via an alternate route. During this metabolism, drug is lost during the process of absorption which is generally related to the liver and gut wall. The liver is the major site of first pass effect; however, it can also occur in the lungs, vasculature or other metabolically active tissues in the body. Notable drugs that experience a significant first-pass effect are buprenorphine, chlorpromazine, cimetidine, diazepam, ethanol, imipramine, insulin, lidocaine, midazolam, morphine, pethidine, propranolol, and tetrahydrocannabinol (THC). First-pass metabolism is not to be confused with Phase I metabolism, which is a separate process.
Sofosbuvir, sold under the brand name Sovaldi among others, is a medication used to treat hepatitis C. It is taken by mouth.
Galidesivir is an antiviral drug, an adenosine analog. It was developed by BioCryst Pharmaceuticals with funding from NIAID, originally intended as a treatment for hepatitis C, but subsequently developed as a potential treatment for deadly filovirus infections such as Ebola virus disease and Marburg virus disease, as well as Zika virus. Currently, galidesivir is under phase 1 human trial in Brazil for coronavirus.
The ProTide technology is a prodrug approach used in molecular biology and drug design. It is designed to deliver nucleotide analogues into the cell. This technology was invented by Professor Chris McGuigan from the School of Pharmacy and Pharmaceutical Sciences at Cardiff University in the early 1990s. ProTides form a critical part of antiviral drugs such as sofosbuvir, tenofovir alafenamide, and remdesivir.
Carbocyclic nucleosides are nucleoside analogues in which a methylene group has replaced the oxygen atom of the furanose ring. These analogues have the nucleobase attached at a simple alkyl carbon rather than being part of a hemiaminal ether linkage. As a result, they have increased chemical stability. They also have increased metabolic stability because they are unaffected by phosphorylases and hydrolases that cleave the glycosidic bond between the nucleobase and furanose ring of nucleosides. They retain many of the biological properties of the original nucleosides with respect to recognition by various enzymes and receptors.
Remdesivir, sold under the brand name Veklury, is a broad-spectrum antiviral medication developed by the biopharmaceutical company Gilead Sciences. It is administered via injection into a vein. During the COVID‑19 pandemic, remdesivir was approved or authorized for emergency use to treat COVID‑19 in numerous countries.
Silmitasertib (INN), codenamed CX-4945, is a small-molecule inhibitor of protein kinase CK2, a constitutively active serine/threonine-specific protein kinase that is overexpressed in several types of tumors.
GS-6620 is an antiviral drug which is a nucleotide analogue. It was developed for the treatment of Hepatitis C but while it showed potent antiviral effects in early testing, it could not be successfully formulated into an oral dosage form due to low and variable absorption in the intestines which made blood levels unpredictable. It has however continued to be researched as a potential treatment for other viral diseases such as Ebola virus disease.
Valopicitabine (NM-283) is an antiviral drug which was developed as a treatment for hepatitis C, though only progressed as far as Phase III clinical trials. It acts as an RNA-dependent RNA polymerase inhibitor. It is a prodrug which is converted inside the body to the active form, 2'-C-methylcytidine triphosphate.
GS-441524 is a nucleoside analogue antiviral drug which was developed by Gilead Sciences. It is the main plasma metabolite of the antiviral prodrug remdesivir, and has a half-life of around 24 hours in human patients. Remdesivir and GS-441524 were both found to be effective in vitro against feline coronavirus strains responsible for feline infectious peritonitis (FIP), a lethal systemic disease affecting domestic cats. Remdesivir was never tested in cats, but GS-441524 has been found to be effective treatment for FIP.
Sangivamycin is a natural product originally isolated from Streptomyces rimosus, which is a nucleoside analogue. It acts as an inhibitor of protein kinase C. It has antibiotic, antiviral and anti-cancer properties and has been investigated for various medical applications, though never approved for clinical use itself. However, a number of related derivatives continue to be researched.
Nirmatrelvir is an antiviral medication developed by Pfizer which acts as an orally active 3C-like protease inhibitor. It is part of a nirmatrelvir/ritonavir combination used to treat COVID-19 and sold under the brand name Paxlovid.
Lufotrelvir (PF-07304814) is an antiviral drug developed by Pfizer which acts as a 3CL protease inhibitor. It is a prodrug with the phosphate group being cleaved in vivo to yield the active agent PF-00835231. Lufotrelvir is in human clinical trials for the treatment of COVID-19, and shows good activity against COVID-19 including several variant strains, but unlike the related drug nirmatrelvir it is not orally active and must be administered by intravenous infusion, and so has been the less favoured candidate for clinical development overall.
Bemnifosbuvir is an antiviral drug invented by Atea Pharmaceuticals and licensed to Roche for clinical development, a novel nucleotide analog prodrug originally developed for the treatment of hepatitis C. Bemnifosbuvir is the orally bioavailable hemisulfate salt of AT-511, which is metabolized in several steps to the active nucleotide triphosphate AT-9010, acting as an RNA polymerase inhibitor and thereby interfering with viral replication. Bemnifosbuvir has been researched for the treatment of coronavirus diseases such as that produced by SARS-CoV-2. It showed good results in early clinical trials but had inconsistent results at later stages. Bemnifosbuvir's Phase III study ended early as it failed to meet its primary endpoint of symptom alleviation and did not decrease viral load. However, the drug was well-tolerated and reduced relative hospitalization risk by 71%.
Elsulfavirine is drug used to treat HIV infection. It is a non-nucleoside reverse transcriptase inhibitor (NNRTI). Elsulfavirine is a prodrug which is metabolized to the active antiviral agent deselsulfavirine. It was developed by the Russian company Viriom.
Ensitrelvir, sold under the brand name Xocova is an antiviral medication used as a treatment for COVID-19. It was developed by Shionogi in partnership with Hokkaido University and acts as an orally active 3C-like protease inhibitor. It is taken by mouth.
Deuremidevir, also known as VV116, is an nucleoside analogue antiviral drug. It is administrated through oral tablets, which contain the hydrobromide salt of this drug.
