Antiviral Drugs. Background. Antiretrovirals. Drugs Used in Infections Caused by Respiratory Viruses

Viruses are the smallest and simplest pathogens, necessarily intracellular, that use the metabolic apparatus of the host cell to multiply. To enter into invaded cells, they use pre-existing host structures, so viruses have tropism for those systems that possess these structures, viral infections being generally confined to those tissues and organs. Viral infections have different symptoms; some infections are asymptomatic, others can be severe, even fatal. Viral infections can develop chronically or acutely. When viruses are highly contagious and when new viruses appear, which the host population has not met and for which it has no immunity, epidemics and pandemics can occur. Some viruses are involved in the genesis of cancer. Viruses are classified primarily by the nucleic acid they contain, in DNA viruses and RNA viruses. Antiviral agents have different mechanisms of action, interfering different life cycle stages of different viruses. Pharmacotherapeutic classification of antiviral drugs is made according to the viral infections in which they are active. Antiviral medication is most often used as curative treatment, but some antiviral drugs can also be used prophylactically. Vaccination is the prophylactic method of active immunization, but unfortunately for many viruses there is no vaccine.