Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do not destroy their target pathogen; instead they inhibit its development.
Defective interfering particles (DIPs), also known as defective interfering viruses, are spontaneously generated virus mutants in which a critical portion of the particle's genome has been lost due to defective replication or non-homologous recombination. The mechanism of their formation is presumed to be as a result of template-switching during replication of the viral genome, although non-replicative mechanisms involving direct ligation of genomic RNA fragments have also been proposed. DIPs are derived from and associated with their parent virus, and particles are classed as DIPs if they are rendered non-infectious due to at least one essential gene of the virus being lost or severely damaged as a result of the defection. A DIP can usually still penetrate host cells, but requires another fully functional virus particle to co-infect a cell with it, in order to provide the lost factors.
Zanamivir is a medication used to treat and prevent influenza caused by influenza A and B viruses. It is a neuraminidase inhibitor and was developed by the Australian biotech firm Biota Holdings. It was licensed to Glaxo in 1990 and approved in the US in 1999, only for use as a treatment for influenza. In 2006, it was approved for prevention of influenza A and B. Zanamivir was the first neuraminidase inhibitor commercially developed. It is currently marketed by GlaxoSmithKline under the trade name Relenza as a powder for oral inhalation.
Oseltamivir, sold under the brand name Tamiflu, is an antiviral medication used to treat and prevent influenza A and influenza B (flu). Many medical organizations recommend it in people who have complications or are at high risk of complications within 48 hours of first symptoms of infection. They recommend it to prevent infection in those at high risk, but not the general population. The Centers for Disease Control and Prevention (CDC) recommends that clinicians use their discretion to treat those at lower risk who present within 48 hours of first symptoms of infection. It is taken by mouth, either as a pill or liquid.
Rimantadine is an orally administered antiviral drug used to treat, and in rare cases prevent, influenzavirus A infection. When taken within one to two days of developing symptoms, rimantadine can shorten the duration and moderate the severity of influenza. RImantadine can mitigate symptoms including fever. Both rimantadine and the similar drug amantadine are derivates of adamantane. RImantadine is found to be more effective than amantadine because when used the patient displays fewer symptoms. Rimantadine was approved by the Food and Drug Administration (FDA) in 1994.
Amantadine, sold under the brand name Gocovri among others, is a medication used to treat dyskinesia associated with parkinsonism and influenza caused by type A influenzavirus, though its use for the latter is no longer recommended due to widespread drug resistance. It acts as a nicotinic antagonist, dopamine agonist, and noncompetitive NMDA antagonist. The antiviral mechanism of action is antagonism of the influenzavirus A M2 proton channel, which prevents endosomal escape.
Neuraminidase inhibitors (NAIs) are a class of drugs which block the neuraminidase enzyme. They are commonly used as antiviral drugs because they block the function of viral neuraminidases of the influenza virus, by preventing its reproduction by budding from the host cell. Oseltamivir (Tamiflu) a prodrug, Zanamivir (Relenza), Laninamivir (Inavir), and Peramivir belong to this class. Unlike the M2 inhibitors, which work only against the influenza A, neuraminidase inhibitors act against both influenza A and influenza B. The neuraminidase inhibitors oseltamivir and zanamivir were approved in the US and Europe for treatment and prevention of influenza A and B. Peramivir acts by strongly binding to the neuraminidase of the influenza viruses and inhibits activation of neuraminidase much longer than Oseltamivir or Zanamivir. However, Laninamivir in the cells is slowly released into the respiratory tract, resulting in long-lasting anti-influenza virus activity. Thus the mechanism of the long-lasting activity of laninamivir is basically different from that of Peramivir.
Peramivir is an antiviral drug developed by BioCryst Pharmaceuticals for the treatment of influenza. Peramivir is a neuraminidase inhibitor, acting as a transition-state analogue inhibitor of influenza neuraminidase and thereby preventing new viruses from emerging from infected cells. It is approved for intravenous administration.
Treatments for influenza include a range of medications and therapies that are used in response to disease influenza. Treatments may either directly target the influenza virus itself; or instead they may just offer relief to symptoms of the disease, while the body's own immune system works to recover from infection.
Umifenovir, sold under the brand name Arbidol, is an antiviral medication for the treatment of influenza infection used in Russia and China. The drug is manufactured by Pharmstandard. Russian and China studies have shown it to be effective and it is approved in both countries while, it is not approved by the US FDA for the treatment or prevention of influenza because it was never applied for FDA approval since the drug company is in Russia not the US.
Nitazoxanide, sold under the brand name Alinia among others, is a broad-spectrum antiparasitic and broad-spectrum antiviral medication that is used in medicine for the treatment of various helminthic, protozoal, and viral infections. It is indicated for the treatment of infection by Cryptosporidium parvum and Giardia lamblia in immunocompetent individuals and has been repurposed for the treatment of influenza. Nitazoxanide has also been shown to have in vitro antiparasitic activity and clinical treatment efficacy for infections caused by other protozoa and helminths; evidence as of 2014 suggested that it possesses efficacy in treating a number of viral infections as well.
Influenza, commonly called "the flu", is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These symptoms typically begin 1–4 days after exposure to the virus and last for about 2–8 days. Diarrhea and vomiting can occur, particularly in children. Influenza may progress to pneumonia, which can be caused by the primary viral infection or by a secondary bacterial infection. Other complications of infection include acute respiratory distress syndrome, meningitis, encephalitis, and worsening of pre-existing health problems such as asthma and cardiovascular disease.
Viral neuraminidase is a type of neuraminidase found on the surface of influenza viruses that enables the virus to be released from the host cell. Neuraminidases are enzymes that cleave sialic acid groups from glycoproteins. Neuraminidase inhibitors are antiviral agents that inhibit influenza viral neuraminidase activity and are of major importance in the control of influenza.
The 2009 swine flu pandemic was an influenza pandemic that lasted about 19 months, from January 2009 to August 2010, and was the most recent flu pandemic involving H1N1 influenza virus. First described in April 2009, the virus appeared to be a new strain of H1N1 that resulted from a previous triple reassortment of bird, swine, and human flu viruses and that further combined with a Eurasian pig flu virus, leading to the term "swine flu".
Laninamivir (CS-8958) is a neuraminidase inhibitor that is a drug used for the treatment and prophylaxis of Influenzavirus A and Influenzavirus B. It is currently in Phase III clinical trials. It is a long-acting neuraminidase inhibitor administered by nasal inhalation.
Antiviral proteins are proteins that are induced by human or animal cells to interfere with viral replication. These proteins are isolated to inhibit the virus from replicating in a host's cells and stop it from spreading to other cells. The Pokeweed antiviral protein and the Zinc-Finger antiviral protein are two major antiviral proteins that have undergone several tests for viruses, including HIV and influenza.
Peter Palese is a United States microbiologist and Professor and Chair of the Department of Microbiology at the Icahn School of Medicine at Mount Sinai in New York City, and an expert in the field of RNA viruses.
Favipiravir, sold under the brand name Avigan among others, is an antiviral medication used to treat influenza in Japan. It is also being studied to treat a number of other viral infections, including SARS-CoV-2. Like the experimental antiviral drugs T-1105 and T-1106, it is a pyrazinecarboxamide derivative.
Triazavirin is a broad-spectrum antiviral drug developed in Russia through a joint effort of Ural Federal University, Russian Academy of Sciences, Ural Center for Biopharma Technologies and Medsintez Pharmaceutical. It has a novel triazolotriazine core, which represents a new structural class of non-nucleoside antiviral drugs.
Pimodivir is an antiviral drug which was developed as a treatment for influenza. It acts as an inhibitor of influenza virus polymerase basic protein 2, and has shown promising results in Phase II clinical trials.
