PHARMACOKINETICS AND BIOAVAILABILITY OF METRONIDAZOLE AFTER TABLETS, SUPPOSITORIES AND INTRAVENOUS ADMINISTRATION

  • 1 January 1984
    • journal article
    • research article
    • Vol. 19, 45-60
Abstract
The pharmacokinetics of metronidazole were determined in a cross-over study on 11 healthy volunteers after administration of 400 mg tablets from 2 producers, 1000 mg suppositories and 800 mg i.v. doses. High-pressure liquid chromatography was used to assay unchanged metronidazole (M) and the hydroxy metronidazole metabolite (OH-M). Thie peak concentrations were observed 1.2-1.3 h after administration of the tablets and 4.9 h after suppositories. After the i.v. dose, the OH-M peak appeared after 8 h. The serum half-life [t1/2] was 6.5 h after the i.v. dose, 6.1-6.8 h after the tablets and 6.8 h after the suppositories. After i.v. dosage, the terminal phase distribution volume was 38.1 l and the total body clearance 4.09 l/h. The bioavailability of the tablets was 80.4 and 84.1% and the suppositories 53.8%. The rate of elimination OH-M was faster after suppositories than after i.v. dosage, which was faster than tablets. Accordingly, the serum t1/2 was 9.7 h after suppositories, 19.2 h after i.v. infusion and 10.6 and 11.8 h after the tablets. The rates of apparent metabolism were rated in the same relative order, with a faster rate after the suppositories, 0.168/h compared to 0.368/h after i.v. administration. The differences pertaining to OH-M were probably caused by interaction with the metabolic activity of the bacterial flora of the colon.

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