Relationships between renal function and disposition of oral ciprofloxacin

The relationships between creatinine clearance (CLCR) and the pharmacokinetics of oral ciprofloxacin were characterized. On the basis of these data, a dosage adjustment strategy, which incorporates the severity of infection and the size and renal function of the patient, was developed. An adaptive (feedback) control algorithm is proposed. A total of 32 subjects (8 normal, 8 anuric, and 16 with CLCR between 0.53 and 4.3 liters/h per 1.73 m2) were given a single 750-mg tablet of ciprofloxacin by mouth. Serial serum and urine samples were collected, assayed by high-pressure liquid chromatography, and comodeled. The population relationship between total apparent ciprofloxacin clearance (CL/f) and CLCR, both measured in liters per hour per 1.73 m2, was CL/f = 2.83 x CLCR + 21.8 (r = 0.69; P less than 0.001). The mean terminal half-life was not significantly related to CLCR but was much more variable in subjects with CLCR less than 3 liters/h per 1.73 m2 (F = 4.8; P less than 0.005). We conclude that patients with CLCR less than 1.2 liters/h per 1.73 m2 should receive two-thirds of the normal daily dose and that the dose interval should not be lengthened.