This prospective, randomized, single-blind, cross-over study will compare the bioavailability of Copegus (ribavirin) administered as tablets and ribavirin administered as capsules in healthy volunteers. Volunteers will be randomized to receive a single dose of 400 mg of ribavirin either as a capsule or as tablets; after a washout phase volunteers will be crossed-over to the other treatment. The anticipated time on study treatment is 10 days.

Inclusion Criteria:

• Adult healthy volunteers, 18 to 55 years of age
• Clinically healthy as confirmed by medical history, physical examination, electrocardiogram, thorax teleradiography and routine clinical laboratory measurements
• Body mass index between 18 and 28 kg/m2
• Negative testing for drugs of abuse

Exclusion Criteria:

• History or presence of any clinically significant condition that might interfere with the pharmacokinetics of the study drugs
• Volunteers require co-medications during the study
• Exposure to agents known as inducers or inhibitors of hepatic enzymatic system within 30 days prior to study start
• Having taken any medication with a clearance period of over seven half-life before study start
• Hospitalization or significant illness 30 days before study start
• Having received a investigational drug within 90 days prior to study start