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/mm3 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