Cinoxacin: pharmacokinetics and tolerance in patients with normal and impaired renal function

The pharmacokinetics of cinoxacin, a new antibacterial compound related to nalidixic acid and oxolinic acid, were investigated in 22 patients with varying degrees of renal impairment. After oral administration of cinoxacin at 500 mg every 12 h for 7 days to all patients, the drug was found to be well tolerated. The urine concentrations of cinoxacin in all patients far exceeded the minimal inhibitory concentrations for susceptible organisms commonly found in urinary tract infections. The serum half-life of cinoxacin in patients with normal renal function was approximately 2.7 h but increased to approximately 8.5 h in patients with creatinine clearance less than 30 ml/min. No undue drug accumulation was demonstrated in any patient group during the treatment. Highly significant correlations were found between the elimination rate constant and creatinine clearance and also between the elimination half-life and serum creatinine. The bioavailability of cinoxacin was independent of renal function.