Antibacterial activity after a single-dose of norfloxacin, ofloxacin and pipemidic acid detected in urine of volunteers.

Six healthy volunteers received in a triple-crossover design a single oral dose of norfloxacin, ofloxacin or pipemidic acid. Urine samples were collected during the 24 h following the administration and were tested for inhibitory and bactericidal activity against selected strains of Enterobacteriaceae and Pseudomonas aeruginosa. Norfloxacin and ofloxacin inhibited the urinary growth of sensitive strains during the 24 h of sampling time at dilutions much higher than those generally considered satisfactory. Nalidixic acid was less effective and did not achieve bactericidal activity against Ps. aeruginosa over the interval of 12 to 24 h.