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. Contraindications Contraindicated in patients hypersensitive to the drug or its components and in women who are or may become pregnant. Vials containing 6 grams of sterile, lyophilized powder to be reconstituted in sterile water for aerosol administration. Oral solutions and intravenous preparations must be compounded since these dosage forms are not commercially available. Solutions in the SPAG-2 unit should be replaced with newly reconstituted solutions every 24 hours.