Pharmacokinetics and absolute bioavailabilty of ciprofloxacin administered through a nasogastric tube with continuous enteral feeding to critically ill patients

Objective: To determine the pharmacokinetics and absolute bioavailability of ciprofloxacin in 12 critically ill patients receiving continuous enteral feeding. Design: a prospective, cross-over study. Setting: 12-bed surgical intensive care unit in a University Hospital. Patients: 12 stable critically ill patients on mechanical ventilation and receiving continuous enteral feeding (Normoreal fibres) without diarrhea or excessive residual gastric contents ( < 200 ml/4 h). None had gastro-intestinal disease, renal insufficiency (estimated creatinine clearance greater than or equal to 50 ml/min) or was receiving medications that could interfere with ciprofloxacin absorption or metabolism. Measurements ann main results: The study was carried out after the fourth (steady state) b.i.d. intravenous (i. v.) 1-h infusion of 400 mg and the second b.i.d. nasogastric (NG) dose of 750 mg (crushed tablet in suspension). Plasma concentrations were measured by high-performance liquid chromatography. The median (range) peak concentration after i. v. infusion was 4.1 (1.5-7.4) mg/l, and that after NG administration was 2.3 (0.7-5.8) mg/l, occurring 1.25 (0.75-3.33)h after dosing. The median [range] areas under plasma concentration-time curves were similar for the two administration routes (10.3 [3.3-34.6] and 8.4 [3.6-53.4] for i.v. infusion and NG administration, respectively). Ciprofloxacin bioavailability ranges from 31 to 82 % (median, 44 %). Conclusions: In tube-fed critically ill patients, a switch to the NG ciprofloxacin after initial i. v. therapy to simplify the treatment of severe infections is restricted to those for whom serial assessments of ciprofloxacin levels are routinely available.