In vitro activity, pharmacokinetics, clinical safety and therapeutic efficacy of enoxacin in the treatment of patients with complicated urinary tract infections.

Minimal inhibitory concentrations (MIC) of enoxacin, nalidixic acid, pipemidic acid, norfloxacin, ciprofloxacin, ofloxacin and pefloxacin against isolates from 400 urological in-patients with complicated urinary tract infections (UTI) were determined by means of an agar dilution technique (10(4) cfu, multipointer). 28 patients (21 male, seven female) aged 36 to 84 years with complicated UTI due to sensitive bacteria were treated orally with 200 mg enoxacin b.i.d. for six to 14 days. Plasma and urine samples were collected from 19 patients, at intervals prior to and following a 400 mg dose of enoxacin, and enoxacin concentrations were determined by a high pressure liquid chromatography (HPLC) method. The MICs of enoxacin against all but one of the gram-negative isolates cultured from 265 urological patients were between 0.03 and 4 mg/l. The MICs against 134 gram-positive isolates were between 0.25 and 16 mg/l except two strains of streptococci. At a concentration of 4 mg/l (8 mg/l), 90.3% (98%) of the total spectrum of isolates were inhibited by enoxacin. Of the quinolones tested, ciprofloxacin appeared to be the most active compound in vitro and cinoxacin the least active antimicrobial agent. The in vitro activity of enoxacin was comparable to that of norfloxacin, ofloxacin and pefloxacin. Oral administration of 400 mg enoxacin to elderly patients resulted in peak serum concentrations between 0.7 and 6.3 mg/l (mean 3.6 mg/l) attained between 1.0 and 6.0 h following drug ingestion. The mean urinary recovery of parent drug within 24 h was 31.2% of the administered dose. 25 of 28 patients treated orally with enoxacin could be followed-up for five to 14 days after the end of treatment. Enoxacin therapy in these patients resulted in 18 cures, one failure and six relapses (same species). The drug was well tolerated and there was no evidence of renal, hepatic or haematological toxicity. Enoxacin appears to be well suited for the treatment of complicated UTI.