Impaired absorption of zidovudine in patients with AIDS-related small intestinal disease.

OBJECTIVES

To investigate the effect of small intestinal disease (SID) on the absorption of zidovudine (ZDV) in patients with AIDS.

METHODS

Fourteen fasted homosexual men with AIDS received a single oral dose of ZDV (5 mg/kg). Nine subjects had clinical evidence of intestinal disease (chronic diarrhoea with wasting) confirmed by reduced fat absorption measured indirectly using the 14C-triolein test. Five subjects had AIDS-related symptoms other than those affecting the gastrointestinal tract with normal fat absorption. Sequential measurements of plasma ZDV including its glucuronide metabolite (GZDV) were obtained using radio-immunoassay and ZDV/GZDV concentrations-time profiles of both groups of subjects were compared. Comparisons were also made for each of the following computed variables: the maximum plasma concentration (Cmax), time to reach Cmax (Tmax), area under the plasma concentration-time curve (AUC0-6 h), the elimination half-life (t 1/2), and apparent oral clearance (CL0).

RESULTS

In patients with SID, Cmax ZDV was reduced (6.39 +/- 3.39 versus 11.51 +/- 5.01 mumol/l; P < 0.05) and Tmax ZDV prolonged (0.81 +/- 0.51 versus 0.40 +/- 0.14 h; P < 0.05) but AUC0-6 h ZDV was no different from the non-SID group (8.03 +/- 2.73 versus 14.56 +/- 9.0 mumol/l-1xh; P = 0.06). There were no differences in t 1/2 ZDV (1.22 +/- 0.20 versus 1.13 +/- 0.30 h) or CL0 ZDV (3017 +/- 1158 versus 1700 +/- 889 ml/min; P > 0.05) between SID and non-SID groups, respectively, and GZDV values were comparable between the two groups.

CONCLUSIONS

These data suggest delayed absorption rather than altered metabolism of ZDV in AIDS-related SID and raise the possibility of drug malabsorption. The clinical efficacy of orally administered low-dose ZDV regimens may require further evaluation in patients with chronic diarrhoea and AIDS.