DISPOSITION OF ROXITHROMYCIN IN PATIENTS WITH NORMAL AND SEVERELY IMPAIRED RENAL-FUNCTION

The disposition of roxithromycin, an investigational macrolide antibiotic, was evaluated in 20 subjects, 10 with normal renal function (creatinine clearance [CL(CR)] of 116 ± 17 ml/min [mean ± standard deviation]) and 10 with severely impaired renal function (CL(CR) of 10.2 ± 2.6 ml/min) after a single 300-mg oral dose. Plasma concentration-time data were analyzed in terms of a one- or two-compartment oral absorption model utilizing nonlinear regression analysis. The terminal elimination half-life was significantly prolonged in the group with severely impaired renal function (15.5 ± 4.7 h) compared with that of the group with normal renal function (7.9 ± 2.5 h). Apparent total body clearance was significantly reduced in the renally impaired (25.3 ± 10.5 ml/min) in relation to the group with normal renal function (48.8 ± 11.1 ml/min). The first-order absorption rate constants and apparent volumes of distribution did not differ between the two groups. These data indicate that the disposition of roxithromycin is significantly delayed in subjects with CL(CR)s of < 15 ml/min and suggest that the roxithromycin dosing interval be doubled for these patients.