Ribavirin Primary HIV infection. The exact mechanism of action of the antiviral activity of ribavirin has not been fully elucidated, but the drug appears to exert its antiviral activity by interfering with RNA and DNA synthesis and subsequently inhibiting protein synthesis and viral replication. Ribavirin is readily absorbed across the cellular plasma membrane, probably via a nucleoside transport mechanism. Phosphorylation of ribavirin occurs principally in virus-infected cells, but also occurs in uninfected cells.
Ribavirin is absorbed systemically from the respiratory tract following nasal and oral inhalation.
Peak plasma ribavirin concentrations generally appear to occur at the end of the inhalation period when the drug is inhaled orally and nasally using SPAG, and increase with increasing duration of the inhalation period. Ribavirin is rapidly absorbed following oral administration, with peak plasma concentrations of the drug occuring within 1-2 hours after administration. Following nasal and oral inhalation, highest ribavirin concentrations are found in the respiratory tract and erythrocytes. Ribavirin is excreted principally in urine. Seizures and asthenia also have been reported with intravenous ribavirin therapy.