Reduced bioavailability of oral Metronidazole in postoperative ileus

Metronidazole has been reported to reduce postoperative anaerobic infectionsfollowing surgical procedures. Because of high cost and poor availability of intravenous metronidazolecompared with that of oral preparation, we decided to measure the serum level of metronidazoleafter oral administration in patients during postoperative ileus, and to evaluate thesubstitution of intravenous metronidazole for the oral product. The present study comprised 45 adult patients undergoing major abdominal surgeryvia long laparatomy incision from Aug to Nov 2003.(500 mg of Metronidazole was administered as a single dose orally to each patient twice, one inileus condition and the other in nonileus condition. Blood sampling was done 1 hour after eachepisode of the drug administration). A significant reduction (P<0.001) was found between the mean serum metronidazoleconcentration (2.90 ± 2.29 SD g/ml) during postoperative ileus, and that of controls(11.07±6.72 SD g/ml). In majority of patients (62.5%), the serum level of metronidazole in ileusdid not reach its minimum inhibitory concentration (3 µg/ml) for the most clinically importantanaerobic bacteria. Postoperative ileus significantly affected the oral absorption of metronidazole. As aresult, if we want to control an active anaerobic infection with a prompt antibiotic therapy, it seemsthat initiating of the therapeutic regimen with oral Metronidazole postoperatively is not justified