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The influence of tuberculosis treatment on efavirenz clearance in patients co-infected with HIV and tuberculosis

Tanuja N. Gengiah; Nicholas H. G. Holford; Julia H. Botha; Andrew L. Gray; Kogieleum Naidoo; Salim Abdool Karim

Title:
The influence of tuberculosis treatment on efavirenz clearance in patients co-infected with HIV and tuberculosis
Author(s):
Gengiah, Tanuja N.
Holford, Nicholas H. G.
Botha, Julia H.
Gray, Andrew L.
Naidoo, Kogieleum
Abdool Karim, Salim
Date:
Type:
Articles
Department:
Epidemiology
Permanent URL:
Book/Journal Title:
European Journal of Clinical Pharmacology
Abstract:
PURPOSE: Drug interactions are of concern when treating patients co-infected with human immunodeficiency virus (HIV) and tuberculosis. Concomitant use of efavirenz (EFV) with the enzyme inducer rifampicin might be expected to increase EFV clearance. We investigated the influence of concomitant tuberculosis treatment on the plasma clearance of EFV. METHODS: Fifty-eight patients were randomized to receive their EFV-containing antiretroviral therapy either during or after tuberculosis treatment. Steady-state EFV plasma concentrations (n = 209 samples) were measured, 83 in the presence of rifampicin. Data were analyzed using a non-linear mixed effects model, and the model was evaluated using non-parametric bootstrap and visual predictive checks. RESULTS: The patients had a median age of 32 (range 19-55) years and 43.1% were women. There was a bimodal distribution of apparent clearance, with slow EFV metabolizers accounting for 23.6% of the population and having a metabolic capacity 36.4% of that of the faster metabolizers. Apparent EFV clearance after oral administration in fast metabolizers was 12.9 L/h/70 kg whilst off tuberculosis treatment and 9.1 L/h/70 kg when on tuberculosis treatment. In slow metabolizers, the clearance estimates were 3.3 and 4.7 L/h/70 kg in the presence and absence of TB treatment, respectively. Overall there was a 29.5% reduction in EFV clearance during tuberculosis treatment. CONCLUSION: Unexpectedly, concomitant rifampicin-containing tuberculosis treatment reduced apparent EFV clearance with a corresponding increase in EFV exposure. While the reasons for this interaction require further investigation, cytochrome P450 2B6 polymorphisms in the population studied may provide some explanation.
Subject(s):
Virology
Epidemiology
Publisher DOI:
http://dx.doi.org/10.1007/s00228-011-1166-5
Item views:
114
Metadata:
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