Serum and tissue concentrations of cefoxitin and cefotaxime in women undergoing hysterectomy

In a comparative study of serum and uterine tissue concentrations of cefoxitin and cefotaxime in patients undergoing hysterectomy, 40 patients were randomised to receive either cefoxitin 2g or cefotaxime 2g by intravenous administration. Serum samples were obtained before drug administration, at the ligation of the uterine arteries and at the end of surgery. Cefoxitin, cefotaxime and desacetylcefotaxime concentrations were determined by high performance liquid chromatography. The composite serum half-lives (determined by linear regression) for cefoxitin, cefotaxime and desacetylcefotaxime were 0.8, 0.7 and 2.1 hours, respectively. Although serum concentrations were higher for cefotaxime than for cefoxitin after a 2g dose, the uterine concentrations (at 40 mins) of cefoxitin were higher (51 micrograms/g vs 16 micrograms/g) than those of cefotaxime. After a 2g dose of cefotaxime the desacetylcefotaxime peak uterine concentration was 8 micrograms/g. Both drugs achieved adequate concentrations in serum and uterine tissue to prevent and treat infections caused by common Enterobacteriaceae such as Escherichia coli, with cefotaxime having a longer apparent duration of activity. However, cefoxitin provided serum and uterine concentrations above the minimum inhibitory concentration of Bacteroides fragilis for a longer period than did cefotaxime.