Bioavailability of oral ciprofloxacin in early postsurgical patients.

OBJECTIVE To evaluate the absorption of oral ciprofloxacin within 24 hours of laparotomy for major elective surgery or peritonitis. DESIGN In this prospective trial, patients were given a 750-mg oral close the morning after major elective surgery (n=15) or surgery for peritonitis (n=7). Healthy volunteers served as controls (n=9). Serial urine and blood samples were drawn during the subsequent 12 hours, and pharmacokinetic measures were determined by standard high-performance liquid chromatography assay procedures. SETTING Multicenter, university-affiliated hospitals. MAIN OUTCOME MEASURES Drug absorption as determined by area under the concentration time curve, maximum concentration, and time to maximum concentration. RESULTS Oral bioavailability was reduced in elective surgery and peritonitis patients compared with controls. Among the 15 elective surgery patients, 27% (4/15) showed no absorption. The remaining 73% (11/15) had an area under the curve comparable with that of controls (8.3+/-1.6 (mg/[L x h]). Among all patients, those who showed drug absorption vs those who showed no absorption did not differ with respect to malignant neoplasm, case type, age, or biochemistry. However, patients showing no absorption were significantly heavier than patients showing absorption (patients showing absorption, 15%+/-3% over ideal body weight vs patients showing no absorption, 29%+/-6% over ideal body weight; P<.05). When elective surgery patients were stratified by presence or absence of obesity (25% above ideal body weight), mean area under the curve in nonobese patients was 9.80+/-2.37 vs 0.91+/-0.56 (mg/(L x h) in obese patients (P<.05). CONCLUSIONS Oral bioavailability was reduced for peritonitis surgery patients on the first day postoperatively, and for obese elective surgery patients. To achieve adequate serum levels requires continuation of intravenous antibiotics in patients with peritonitis, and adjustment of oral dosage in obese patients in the early period after elective surgery.