Cinoxacin concentrations in plasma, urine and prostatic tissue after oral administration to man.

Cinoxacin, a synthetic antibacterial compound, was given orally in a dose of 500 mg to 8 patients undergoing transurethral prostatectomy. The drug was well absorbed and the peak plasma level (mean 13.9 mcg/ml) occurred 1 or 2 hours after administration. Concentrations of cinoxacin in the urine reached a peak (mean 236.5 mcg/ml) 4 to 6 hours after dosing, and remained higher than the mean MIC for most common urinary pathogens for 12 hours after administration. The concentration of cinoxacin in prostatic tissue 2.5-4 hours after administration varied between 0.6 and 6.3 mcg/g. The individual variations were unrelated to the concurrent plasma level and appeared to be influenced more by inter-subject variation than by the physicochemical properties of the drug. In 1 patient the cinoxacin level was estimated in renal tissue (70.1 mcg/g), in muscle (12.6 mcg/g), and in perirenal fat (4.7 mcg/g).