PK Study of Rifampicin Interactions With DMPA and Efavirenz in TB

Globally, women comprise 52% of all people living with human immunodeficiency virus (HIV). Decisions about contraception in a population of women infected with both tuberculosis (TB) and HIV are of paramount importance. In the setting of the treatment of active TB, preventing pregnancy becomes even more important because it allows women to attain a level of health that will support healthy future pregnancies. Treatment options for TB may be limited in pregnancy because of concerns about teratogenicity. Millions of women around the world use depot medroxyprogesterone acetate (DMPA, trade name Depo-Provera) for prevention of pregnancy. DMPA is an intermediate-acting progesterone-only injectable contraceptive with a high efficacy rate. Unfortunately, DMPA's safety and effectiveness among women co-infected with TB and HIV is unknown since the interactions of TB treatment, combination ART (cART), and DMPA have not been well studied. The results of this study are likely to be applicable to women receiving RIF-containing TB treatment who are not being treated concurrently with EFV as well, given that addition of EFV to RIF is unlikely to increase induction of metabolizing enzymes significantly beyond the induction achieved with RIF alone. The study population included premenopausal women, 18 to 46 years of age, who were co-infected with HIV and TB. To be eligible to enroll in the study, participants must have been on EFV 600 mg once daily plus two or more nucleoside reverse transcriptase inhibitors (NRTIs) for at least 28 days prior to study entry with no plans to change therapy for the 12 weeks of the study. Women must have been on the continuation phase of active TB treatment (with a minimum of 12 weeks remaining) taking RIF 8-12 mg/kg orally and INH 4-6 mg/kg orally on a 5-day or more per week schedule (or as directed by national guidelines for TB treatment). At study entry/week 0, DMPA 150 mg was administered intramuscularly as a single dose. Study duration was 12 weeks. Visits occurred at weeks 0, 2, 4, 6, 8, 10, and 12. The key evaluations included physical examination, clinical assessments, hematology, chemistry, HIV RNA, pregnancy testing, plasma progesterone levels, and plasma DMPA concentration levels. The sample size was 46 participants, of which 42 had to be evaluable. Participants who missed two successive visits prior to week 8 and those who did not complete the week 10 and week 12 clinic visits with available DMPA concentrations and progesterone levels were not evaluable and replaced in the sample size. The final number of participants enrolled was 62 participants, with only 42 evaluable.