Trimethoprim-sulphamethoxazole and metronidazole as prophylaxis in colorectal surgery: A study of bioavailability after an oral single dose

Objective: To evaluate oral single dose prophylaxis in colorectal surgery. Design: Prospective study. Setting: University hospital, Sweden. Subjects: 24 patients (13 women; 11 men; mean age 57 years, range 27-81) Li sted for elective colorectal operations. Intervention: At 0630 on the day of the operation ail patients were given a n oral dose of trimethoprim-sulphamethoxazole (TMP 160 mg and SMZ 800 mg) a nd metronidazole (2 g). The serum concentrations of TMP and SMZ were analys ed in Venous samples taken at the start and end of each operation. Results: The earliest operation started at 0830 and the last finished at 17 00. The median (range) serum concentrations of TMP were 1.4 (0.7-2.6) mg/L (start) and 1.3 (1.0-2.8) mg/L (end), and of SMZ 35 (15-65) mg/L (start) an d 33 mg (13-70) mg/L (end). The individual values were above or equal to th e minimal inhibitory concentration (TMP 0.8 mg/L; SMZ 15.2 mg/L) for releva nt Grain-negative species. Conclusion: Oral TMP/SMZ in the morning gives satisfactory serum concentrat ions independently of when the operation is done during the day. The regime n is simple and has the potential for being an effective alternative to int ravenous prophylaxis.