Eleni Aklillu1, Alimuddin Zumla2,3, Abiy Habtewold4, Wondwossen Amogne5, Eyasu Makonnen6, Getnet Yimer6, Jürgen Burhenne7, Ulf Diczfalusy8. 1. Division of Clinical Pharmacology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge C1:68, Karolinska Institutet, Stockholm, Sweden. 2. Division of Infection and Immunity, University College London, NIHR Biomedical Research Centre at UCL Hospitals NHS Foundation Trust, London, UK. 3. UNZA-UCLMS Research and Training Program, Department of Medicine, University Teaching Hospital, Lusaka, Zambia. 4. Department of Pharmaceutical Sciences, School of Pharmacy, William Carey University, Biloxi, MS, USA. 5. Department of Internal Medicine, College of Health Science, Addis Ababa University, Addis Ababa, Ethiopia. 6. Department of Pharmacology, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia. 7. Department of Clinical Pharmacology and Pharmacoepidemiology, University of Heidelberg, Heidelberg, Germany. 8. Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital, Stockholm, Sweden.
Abstract
BACKGROUND AND PURPOSE: In TB-HIV co-infection, prompt initiation of TB therapy is recommended but anti-retroviral treatment (ART) is often delayed due to potential drug-drug interactions between rifampicin and efavirenz. In a longitudinal cohort study, we evaluated the effects of efavirenz/rifampicin co-treatment and time of ART initiation on CYP3A induction. EXPERIMENTAL APPROACH: Treatment-naïve TB-HIV co-infected patients (n = 102) were randomized to efavirenz-based-ART after 4 (n = 69) or 8 weeks (n = 33) of commencing rifampicin-based anti-TB therapy. HIV patients without TB (n = 94) receiving efavirenz-based-ART only were enrolled as control. Plasma 4β-hydroxycholesterol/cholesterol (4β-OHC/Chol) ratio, an endogenous biomarker for CYP3A activity, was determined at baseline, at 4 and 16 weeks of ART. KEY RESULTS: In patients treated with efavirenz only, median 4β-OHC/Chol ratios increased from baseline by 269% and 275% after 4 and 16 weeks of ART, respectively. In TB-HIV patients, rifampicin only therapy for 4 and 8 weeks increased median 4β-OHC/Chol ratios from baseline by 378% and 576% respectively. After efavirenz/rifampicin co-treatment, 4β-OHC/Chol ratios increased by 560% of baseline (4 weeks) and 456% of baseline (16 weeks). Neither time of ART initiation, sex, genotype nor efavirenz plasma concentration were significant predictors of 4β-OHC/Chol ratios after 4 weeks of efavirenz/rifampicin co-treatment. CONCLUSION AND IMPLICATIONS: Rifampicin induced CYP3A more potently than efavirenz, with maximum induction occurring within the first 4 weeks of rifampicin therapy. We provide pharmacological evidence that early (4 weeks) or deferred (8 weeks) ART initiation during anti-TB therapy has no significant effect on CYP3A induction. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc.
BACKGROUND AND PURPOSE: In TB-HIV co-infection, prompt initiation of TB therapy is recommended but anti-retroviral treatment (ART) is often delayed due to potential drug-drug interactions between rifampicin and efavirenz. In a longitudinal cohort study, we evaluated the effects of efavirenz/rifampicin co-treatment and time of ART initiation on CYP3A induction. EXPERIMENTAL APPROACH: Treatment-naïve TB-HIV co-infectedpatients (n = 102) were randomized to efavirenz-based-ART after 4 (n = 69) or 8 weeks (n = 33) of commencing rifampicin-based anti-TB therapy. HIVpatients without TB (n = 94) receiving efavirenz-based-ART only were enrolled as control. Plasma 4β-hydroxycholesterol/cholesterol (4β-OHC/Chol) ratio, an endogenous biomarker for CYP3A activity, was determined at baseline, at 4 and 16 weeks of ART. KEY RESULTS: In patients treated with efavirenz only, median 4β-OHC/Chol ratios increased from baseline by 269% and 275% after 4 and 16 weeks of ART, respectively. In TB-HIVpatients, rifampicin only therapy for 4 and 8 weeks increased median 4β-OHC/Chol ratios from baseline by 378% and 576% respectively. After efavirenz/rifampicin co-treatment, 4β-OHC/Chol ratios increased by 560% of baseline (4 weeks) and 456% of baseline (16 weeks). Neither time of ART initiation, sex, genotype nor efavirenz plasma concentration were significant predictors of 4β-OHC/Chol ratios after 4 weeks of efavirenz/rifampicin co-treatment. CONCLUSION AND IMPLICATIONS: Rifampicin induced CYP3A more potently than efavirenz, with maximum induction occurring within the first 4 weeks of rifampicin therapy. We provide pharmacological evidence that early (4 weeks) or deferred (8 weeks) ART initiation during anti-TB therapy has no significant effect on CYP3A induction. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc.