Urine levels of rifampicin & isoniazid in asymptomatic HIV-positive individuals.

Ramachandran, G.; Hemanth Kumar, A.K.; Sarala, K.; Padmapriyadarsini, C.; Anitha, S.; Tharani, C.B.; Kumaraswami, V.; Swaminathan, S.

Indian Journal of Medical Research; 2007; 125:763-766.

Background & objectives : AIDS and its associated gastrointestinal complications may impair the absorption of anti-tuberculosis (TB) drugs. Impaired absorption of anti-TB drugs could lead to low drug exposure, which might contribute to acquired drug resistance and reduced effectiveness of anti-TB treatment. The aim of this study was to obtain information on the status of absorption of rifampicin (RMP) and isoniazid (INH) in asymptomatic HIV- positive individuals, who are less immunocompromised. The D-xylose absorption test was also carried out to assess the absorptive capacity of intestive.

Methods : The absorption of RMP, INH and D-xylose was studied in 15 asymptomatic HIV- positive individuals with CD4 cell counts > 350 cells/mm 3 and 16 healthy volunteers, after oral administration of single doses of RMP (450 mg), INH (300 mg) and D-xylose (5 g). Urine was collected up to 8 h after drug administration. Percentage dose of the drugs and their metabolites and D-xylose excreted in urine were calculated.

Results : A significant reduction in the urinary excretion of INH and D-xylose in HIV-positive persons compared to healthy volunteers was observed. The per cent dose of RMP and its metabolite, desacetyl RMP was also lower in HIV-positive persons compared to healthy volunteers, but this difference was not statistically significant.

Interpretation & conclusion : Decreased urinary excretion of D-xylose and INH are suggestive of intestinal malabsorption in HIV-positive individuals. HIV infection could cause malabsorption of anti-TB drugs even at an early stage of the disease. The clinical implications of these findings need to be confirmed in larger studies.

Keywords : Asymptomatic HIV infection - isoniazid - malabsorption - rifampicin

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