Primary objective: To compare the pharmacokinetics of rifapentine and 25-desacetyl rifapentine at three different doses: 600 mg, 900 mg, and 1200 mg.

Secondary objective: To describe any correlation between pharmacokinetic parameters of three different doses of rifapentine plus a standard dose of isoniazid and the occurrence of toxicity attributed to anti-tuberculosis treatment.

We will enroll 24-36 patients, 8-12 at each dose of 600, 900 and 1200 mg rifapentine Admissions for pharmacokinetic studies will take place during the continuation phase of tuberculosis therapy. Patients participating in a double-blinded trial of the tolerability and safety of higher doses of rifapentine during continuation phase therapy and consenting to participate in the pharmacokinetic study may be admitted to a Clinical Research Center (CRC) to allow for frequent blood sampling over a 24-hour period. Otherwise, patients will be evaluated in the clinic.

Inclusion:

Patients enrolled in TBTC Study 25 Informed consent

Exclusion:

Severe anemia (Hct <25%) Any severe adverse event related to study drugs in TBTC Study 25