Pharmacokinetics of rifabutin in HIV-infected patients with or without wasting syndrome

Aims The purpose of the study was to compare the pharmacokinetic parameters of rifabutin obtained in a group of patients without wasting syndrome (NWS ) with those obtained in a group with wasting syndrome (WS). Methods A single dose of 300 mg rifabutin was administered in the fasting s tate to the patients in both study groups and blood samples were scheduled to be collected at the following times: 0 (predose), 0.5, 1, 2, 3, 4, 6, 8, 24, 48, 72 and 96 h following administration. Data were analysed using non compartmental methods. The pharmacokinetic parameters of rifabutin in patie nts with and without wasting syndrome were compared using the Mann-Whitney U-test. Results C-max was 0.34 +/- 0.14 mg l(-1) in NWS patients and 0.55 +/- 0.16 mg l(-1) (P = 0.01) in patients with WS. t(max) was 4.2 +/- 1.5 and 3.3 +/- 2.3 h (P = 0.17) in NWS and WS patients, respectively. The AUCs were simil ar in the two study groups. V/F was 2905 +/- 1646 l in NWS patients and 170 1 +/- 492 l (P = 0.07) for the WS group. These differences are less pronoun ced following normalization of V/F to patients body weight (43.7 +/- 20.1 v s 35.4 +/- 10.3 1 kg(-1)). t(1/2,lambda z) tended to be shorter in patients with WS (31.4 +/- 12.9 vs 46.0 +/- 23.5 h, P = 0.12). Conclusions Our study suggests that the pharmacokinetics of rifabutin in pa tients with wasting syndrome are not altered to a degree that is clinically important.