Antivirali

Antivirali are medications designed to treat viral infections by inhibiting steps in the viral life cycle or by inactivating viral particles. They aim to reduce viral replication, lessen illness duration and severity, prevent complications, and decrease transmission when used appropriately. Antivirals are generally virus-specific or mechanism-specific and are usually prescribed by healthcare professionals.

Most antivirals work by targeting a specific stage of viral replication. Common classes include nucleoside or nucleotide analogues that inhibit viral polymerases, protease inhibitors that block processing of viral proteins, and polymerase inhibitors that directly disrupt viral RNA or DNA synthesis. Other agents act as entry inhibitors, preventing viruses from attaching to or fusing with host cells, or as integrase inhibitors that block incorporation of viral DNA into the host genome. Some antivirals are designed for particular viruses and are used in combination therapies to improve efficacy and reduce resistance.

Key agents and targets include oseltamivir and other neuraminidase inhibitors for influenza; acyclovir, valacyclovir, and famciclovir for herpesviruses; ganciclovir and valganciclovir for cytomegalovirus; and a range of therapies for HIV and hepatitis C, including reverse transcriptase inhibitors, protease inhibitors, and integrase inhibitors. For emergent diseases, antivirals such as remdesivir for RNA viruses and nirmatrelvir/ritonavir for SARS-CoV-2 have played significant roles. Sofosbuvir-based regimens are widely used for hepatitis C.

Resistance can develop with improper use or prolonged therapy, limiting effectiveness and necessitating monitoring and stewardship. Safety profiles vary by drug and patient factors, with considerations for pregnancy, comorbidities, and drug interactions.