antiviralsed

Antivirals are medications designed to treat infections caused by viruses. They work by inhibiting steps of the viral life cycle, thereby suppressing viral replication rather than killing infected cells. Because viruses rely on host cells to replicate, antiviral drugs tend to be virus-specific and are chosen to target the causative pathogen. Early treatment often improves outcomes, and in some infections no effective antiviral therapy is available.

Antiviral actions fall into several categories. Nucleoside and nucleotide analogues resemble natural building blocks of viral genomes and terminate replication. Enzyme inhibitors block viral polymerases, proteases, or integrases, interrupting replication or assembly. Entry inhibitors or fusion inhibitors prevent viruses from entering cells. Some agents are monoclonal antibodies that neutralize viruses, providing passive immunity in selected cases. Treatments may be used alone or in combination, depending on the infection and the pathogen.

Examples by disease area include: influenza—neuraminidase inhibitors oseltamivir and zanamivir, and baloxavir marboxil (an endonuclease inhibitor); herpesviruses—acyclovir, valacyclovir, famciclovir; HIV—nucleoside and non-nucleoside reverse transcriptase inhibitors, protease inhibitors, and integrase inhibitors; hepatitis C—direct-acting antivirals such as sofosbuvir (polymerase inhibitor) combined with ledipasvir or velpatasvir; hepatitis B—entecavir and tenofovir; COVID-19—remdesivir (RNA polymerase inhibitor); RSV—ribavirin and the monoclonal antibody palivizumab for prevention in high-risk infants.

Limitations include the development of resistance, drug toxicity, limited activity against some viruses, and the need for timely administration. Antivirals are typically part of broader management that includes vaccination and supportive care, and ongoing research continues to expand their scope and effectiveness.