Antiviral Drugs

Antiviral Drugs are medications approved by the FDA for the treatment or control of viral infections to minimize symptoms and infectivity and shorten the duration of illness. Most of the antivirals available are used to treat HIV, herpes Virus, Hepatitis B and C viruses, and Influenza A and B viruses. These molecules mainly target specific stage(s) in the viral life cycle, eg, attachment to host, uncoating, synthesis of viral mRNA, translation of V-mRNA, replication of V-DNA or V-RNA, assembly of progeny virus, budding or release of the new viruses and free virus in body fluids. Antiviral drugs are classified based on their respective targetted action, eg, entry blockers preventing virus entry to the host; nucleoside/nucleotide analogs interfere with virus genome synthesis.

It is difficult to find drugs selective for the virus as they are obligate intracellular parasites. These non-living virus particles acquire life in a specific living host using host metabolic processes. Antiviral drugs are not typical antibiotics that act on different metabolic stages of living bacterial cells, ultimately neutralizing them. Antibiotics do not act on the virus, and the virus protein-specific antivirals do not kill/inactivate viruses, but through interfering with virus replication, they reduce virus load within the host, allowing the innate immune system of the body to neutralize the virus. If the targets are common among different viruses of the same family, then the drug will show overall effectiveness.

Antiviral drug resistance is an obstacle to antiviral therapy, is decreased susceptibility to the drug caused by changes in virus genotype. In RNA viruses, like Flu/coronavirus, the absence of a ‘foolproof’ mechanism of correction of mistakes generated during genome replication by RNA polymerase exists. So the question of antiviral drug resistance is there. [Mamun Rashid Chowdhury]