Prevention of TB using rifampicin plus isoniazid reduces nevirapine concentrations in HIV-exposed infants.

Background: Newborns of HIV-infected mothers are given daily doses of nevirapine to prevent HIV-1 acquisition. Infants born to mothers with TB should also receive TB preventive therapy. TB preventive regimens include isoniazid for 6 months or rifampicin plus isoniazid for 3 months (RH preventive therapy). The effect of concomitant RH preventive therapy on nevirapine concentrations in infants is unknown. Patients and methods: Tshepiso was a prospective case-control cohort study of pregnant HIV-infected women with and without TB whose newborn infants received standard doses of nevirapine for HIV prophylaxis. Infants born to mothers with TB also received RH preventive therapy. Infant plasma nevirapine concentrations were measured at 1 and 6 weeks. The effects of RH preventive therapy on nevirapine disposition were investigated in a population pharmacokinetic model. Results: Of 164 infants undergoing pharmacokinetic sampling, 46 received RH preventive therapy. After adjusting for weight using allometric scaling, the model estimated a 33% reduction in nevirapine trough concentrations with RH preventive therapy compared with TB-unexposed infants not receiving concomitant rifampicin and a 30% decline in trough concentrations in a typical infant between day 7 and 35 post-partum. Conclusions: Rifampicin-based TB preventative treatment reduces nevirapine concentrations significantly in HIV-exposed infants. Although the nevirapine exposures required to prevent HIV acquisition in breastfeeding infants are undefined, given the potential risks associated with underdosing nevirapine in this setting, it is prudent to avoid rifampicin-based preventive therapy in HIV-exposed children receiving prophylactic nevirapine.

Pharmacokinetics of efavirenz and treatment of HIV-1 among pregnant women with and without tuberculosis coinfection.

BACKGROUND: Pregnancy and tuberculosis treatment or prophylaxis can affect efavirenz pharmacokinetics, maternal human immunodeficiency virus type 1 (HIV-1) treatment outcomes, and mother-to-child transmission (MTCT) risk. METHODS: We evaluated a prospective cohort of pregnant, HIV-infected women with and without tuberculosis in Soweto, South Africa. Pharmacokinetic sampling was performed at gestation week 37 and during the postpartum period. Efavirenz trough concentrations (Cmin) were predicted using population pharmacokinetic models. HIV-viral load was measured at delivery for mothers and at 6 weeks of age for infants. RESULTS: Ninety-seven women participated; 44 had tuberculosis. Median efavirenz Cmin during pregnancy was 1.35 µg/mL (interquartile range [IQR], 0.90-2.07 µg/mL; 27% had an efavirenz Cmin of < 1 µg/mL), compared with a median postpartum value of 2.00 µg/mL (IQR, 1.40-3.59 µg/mL; 13% had an efavirenz Cmin of < 1 µg/mL). A total of 72% of pregnant women with extensive CYP2B6 genotypes had an efavirenz Cmin of <1 µg/mL. Rifampin did not reduce the efavirenz Cmin. Isoniazid (for prophylaxis or treatment), though, reduced the rate of efavirenz clearance. At delivery, median durations of ART were 13 weeks (IQR, 9-18 weeks) and 21 weeks (IQR, 13-64 weeks) for women with and those without tuberculosis, respectively; 55% and 83%, respectively, had a viral load of <20 copies/mL (P = .021). There was 1 case of MTCT. CONCLUSIONS: Pregnancy increased the risk of low efavirenz concentrations, but MTCT was rare. A detectable HIV-viral load at delivery was more common among pregnant women with tuberculosis, in whom ART was generally initiated later.

Tobacco Smoking and Tuberculosis among Men Living with HIV in Johannesburg, South Africa: A Case-Control Study.

SETTING: Although there is ample evidence that smoking increases the risk of tuberculosis (TB), the magnitude of impact on TB risk among HIV-infected persons is poorly described. Given that a high proportion of patients with TB are co-infected with HIV in South Africa, the risks arising from the intersection of smoking, TB, and HIV/AIDS have key relevance for tobacco control policies. OBJECTIVE: To evaluate the association of pulmonary tuberculosis (PTB) with current tobacco smoking among men with HIV in South Africa. DESIGN: Case-control study of antiretroviral therapy naïve men with confirmed HIV-infection in Johannesburg. Cases had laboratory-confirmed PTB and controls had no evidence of active TB. Participants were interviewed to collect detailed smoking histories. RESULTS: We enrolled 146 men diagnosed with PTB and 133 controls. Overall, 33% of participants were currently smoking, defined as smoking a cigarette within 2 months (34% cases vs. 32% controls, p = 0.27). Median CD4 count was lower (60 vs. 81 cells/mm3, P = 0.03) and median viral load was higher (173 vs. 67 copies/ul per thousand, P<0.001) among cases versus controls. In adjusted analyses, current smoking tripled the odds of PTB (aOR 3.2; 95%CI: 1.3-7.9, P = 0.01) and former smoking nearly doubled the odds of PTB (aOR 1.8; 95%CI 0.8-4.4, P = 0.18) compared to never smoking. CONCLUSIONS: Males with HIV that smoke are at greater odds for developing PTB than non-smokers. Extensive smoking cessation programs are needed to reduce odds of TB and promote health among adults living with HIV.