Penetration of metronidazole to tissues.

One dose of 500 mg metronidazole (M) was given to 21 patients before appendectomy and the concentrations of the parent compound and the major metabolite hydroxymetronidazole (OH-M), assayed in serum and tissue homogenates of appendix and subcutaneous tissues by high pressure liquid chromatography. Based on determinations in one specimen per patient during the initial 1.25-4 h after end of the 50 min infusion, the levels of M in relation to serum were 60.8% (+/- S.D. 19.8) for the appendix and 29.0% +/- 8.7 for subcutaneous tissue. The corresponding values for OH-M were 103.9 +/- 28.2 and 57.0% +/- 16.8. The slope of the log-linear regression curves of M corresponded to elimination half-life (T 1/2) values of 5.2 h in serum, 2.7 h in appendix and 2.6 h in subcutis tissue, but the differences were not statistically significant. The values of OH-M were similar for serum and appendix. OH-M had T 1/2 of 7.9 and 6.1 h for serum and subcutaneous tissue and 21.3 h in the appendix, but the values were not significantly different.