Drug Interaction Study With Ribavirin and Abacavir in Male Subjects With Hepatitis C Who Have Failed Ribavirin Treatment

Abacavir is an anti-HIV drug that belongs to the class of nucleosides reverse transcriptase
inhibitors. Ribavirin is a drug used to treat hepatitis C infection. Both abacavir and
ribavirin are approved by the Food and Drug administration (FDA). The doses of abacavir and
ribavirin used in this study are also FDA approved.Some individuals who have HIV infection
also have hepatitis C. It is possible that they may need to take both abacavir to treat HIV
and ribavirin to treat hepatitis C. Recent studies suggest that abacavir decreases the level
of ribavirin in the body (in the blood and in cells named peripheral blood mononuclear cells
or PBMCs). Thus, taking ribavirin and abacavir together could lead to treatment failure for
hepatitis C. So it is important to understand how levels of ribavirin medication are
affected when the two medications are taken together.

Inclusion Criteria:

- HCV-monoinfected male subjects who previously failed RBV-based therapy for hepatitis
C infection, and are currently not receiving therapy for hepatitis C; at least 18-55
years of age.

- Negative HIV-1 serology documented by any licensed ELISA test kit within 30 days
prior to study entry.

- Positive HCV antibody documented within 30 days prior to study entry.

- Negative HLA-B*5701 test documented within 30 days prior to study entry.

- Ability and willingness of subject to provide a signed informed consent and comply
with study requirements.

- All male subjects must not participate in a conception process (e.g., active attempt
to impregnate, sperm donation, in vitro fertilization). If participating in sexual
activity that could lead to pregnancy, male subjects must take every precaution to
avoid risk of pregnancy for their female partners by using reliable contraception
(condom) while receiving study therapy and for 6 months following permanent
discontinuation of study therapy. Subjects will also be instructed to counsel their
female partners regarding fetal risk and need for appropriate contraception (e.g.,
hormonal, barrier) so as a secondary effort to prevent pregnancy even though the
female partners will not be study participants.

- Estimated creatinine clearance ≥50 mL/minute, within 30 days prior to study entry

- Laboratory values obtained within 30 days prior to study entry:

- Hgb within the normal limits as defined by the reporting laboratory

- AST (SGOT), ALT (SGPT), and alkaline phosphatase >5 x ULN as defined by the reporting
laboratory.

- Direct bilirubin ≤1.5 x UNL as defined by the reporting laboratory.

- Subject has not consumed alcohol in the 48 hours prior to the administration of study
drugs.

- Framingham cardiovascular disease risk score <10%.

Exclusion Criteria:

- As determined by the investigator, a significant active or previous history of
cardiovascular, renal, hematologic, neurologic, gastrointestinal, psychiatric,
endocrine, or immunologic disease (s). This inclusive of chronic illnesses such as
hypertension, coronary artery disease, arthritis, diabetes, any chronic
gastrointestinal condition that may affect drug absorption. History of chronic or
acute medical condition that in the opinion of the investigator would jeopardize
safety of subjects participating in this study. Any other medical or psychological
condition that might, in the opinion of the site investigator, interfere with
participation in the study or put subjects at undue risk.

- History of anemia, hemoglobinopathy or any other cause of or tendency to hemolysis.

- History of RBV-induced anemia that required dose reduction or discontinuation of RBV
therapy while receiving treatment for hepatitis C infection in the past. Patients who
required treatment with erythropoietin or blood transfusion for the management of
RBV-associated anemia will be excluded from participating in the study.

- Use of prescription or over-the-counter medications, including herbal products,
within 30 days prior to study entry that in the opinion of the investigator would
preclude study participation.

- Men with a pregnant female partner.

- Active drug use or dependence that, in the opinion of the investigator, would
interfere with adherence to study requirements, and/or currently receiving methadone
replacement therapy for the treatment of substance abuse.

- Inability of abstaining from alcohol-containing beverages for the duration of the
study.

- Hospitalization or therapy for serious illness within 30 days prior to study entry as
judged by the investigator.

- Known or suspected HSR to study drugs or their formulations.

- Participation in any investigational drug study within 30 days prior to study entry.

- Active or history of gout disease.