Transintestinal elimination of ciprofloxacin in humans--concomitant assessment of its metabolites in serum, ileum and colon.

Ciprofloxacin (200 mg) was infused to seven patients at the beginning of elective colorectal surgery. Thirty minutes after the end of infusion (i.e. 60 min after the start of the operation) ciprofloxacin reached concentrations of 1.60 mg/l in serum and of 3.42-6.07 mg/kg fresh weight in the ileum and colon. During the next 30 min (90 min after the start of operation) the concentration of ciprofloxacin in serum decreased to 86% of its initial level, but this decrease was less rapid than that observed in the ileal (to 56.8%) or colonic (to 74.8%) mucosa. Three metabolites could be identified (desethylen-, sulpho-, oxociprofloxacin). Initially, at 60 min the amount of these metabolites was about 15% of the total drug concentration in serum, but only 2-3% of that in the gut tissues. At 90 min the relative amount of metabolites was increased in serum as well as in the gut tissues. It is concluded that transintestinal elimination of ciprofloxacin is a general feature of the whole gut. Obviously, the elimination process is not due to degradation of ciprofloxacin within the gut wall.