The purpose of this study is to determine if a relationship exists between the level of antituberculosis drugs (isoniazid, rifampin, ethambutol, and pyrazinamide) in the blood and the outcome of HIV-positive patients with tuberculosis. This study also evaluates how these drugs are absorbed and metabolized in the body.

Patients receive up to 8 weeks of two or more anti-tuberculosis drugs, of which at least two are isoniazid, rifampin, pyrazinamide, or ethambutol. Blood specimens are collected at 2, 6, and 10 hours after administration of study medication, once between Days 10 and 14 of a phase of daily treatment and once while on an intermittent dose regimen (twice weekly or three times weekly).

Inclusion Criteria

You may be eligible for this study if you:

• Are HIV-positive and have tuberculosis.
• Are 13 years of age or older.
• Have written, informed consent of parent or guardian if you are under 18 years of age.
• Agree to practice abstinence or use barrier methods of birth control during the study.

Exclusion Criteria

You will not be eligible for this study if you:

• Have any other disorder or condition which might cause study treatment to be undesirable.
• Are pregnant.