Pharmacokinetics and Safety of Rifabutin 150 mg Once Daily Versus Rifabutin 300 mg Thrice Weekly

Inclusion Criteria: 1. Confirmed HIV positive after voluntary counseling and testing 2. Aged \>18-60years of age 3. PI-naïve (NNRTI intolerance/failure) or PI experience ( TB developed during on salvage regimen) without prior PI mutation 4. Any CD4 cell count 5. ALT \<5 times ULN 6. Serum creatinine \<1.4 mg/dl 7. Hemaglobin \>7 mg/L 8. TB is diagnosed and planned to receive stable doses of rifabutin containing anti-TB therapy for at least another 4 week period after initiation of ART 9. No other active OI (CDC class C event), except oral candidiasis or disseminated MAC 10. Body weight \>40kg 11. Able to provide written informed consent Exclusion Criteria: 1. Current use of steroid (except short course steroid for IRIS) and other immunosuppressive agents. 2. Current use of any prohibited medications related to drug pharmacokinetics. 3. Patients with current alcohol or illicit substance use that in the opinion of the site Principal Investigator would conflict with any aspect of the conduct of the trial. 4. Unlikely to be able to remain in follow-up for the protocol defined period. 5. Patients with proven or suspected acute hepatitis. Patients with chronic viral hepatitis are eligible provided ALT, AST \< 5 x ULN. 6. Karnofsky performance score \<30% 7. TB meningitis and bone/joints ( due to longer period of anti TB drug) 8. Pregnancy 9. Patient choose to use efavirenz, not LPV/r. However, in ART naïve, EFV is allowed after intensive PK of LPV/r and rifabutin at week 2-4.