Ribavirin is a synthetic drug with a pronounced antiviral effect. Ribavirin penetrates into virus-infected cells, blocks the formation of viral RNA, and thereby inhibits the multiplication of viruses. Ribavirin is highly active against herpes simplex virus type 1 and 2, cytomegalovirus , adenovirus, influenza A and B virus parainfluenza, hepatitis C virus, mumps, hemorrhagic fever, smallpox and some other viruses. Insensitive to the drug: the herpes zoster virus, smallpox, pseudorabies, enteroviruses, rhinoviruses. Ribavirin is well absorbed in the digestive tract; in the bloodstream penetrates into the erythrocytes, and in the respiratory organs - in the secret of the glands of the mucous membrane. With long-term use falls into the cerebrospinal fluid. The maximum concentration of this antiviral drug in the blood is noted 1.5 hours after admission. Plasma accumulates in large quantities. It is excreted from the body with urine very slowly (about 300 hours after cessation of administration).