Current clinical applications and dose regimens of metronidazole and related nitroimidazoles

Metronidazole, in particular, and the other nitroimidazoles (tinidazole, ornidazole) available in Australia are well established drugs for the treatment of protozoal (trichomonal or amoebic) infections; recent data testify to their efficacy in the prevention and therapy of anaerobic infections. Administration by oral and rectal routes is indicated rather than by the intravenous route on the basis of efficacy, safety and cost; this recommendation is applicable to both loading and maintenance dosing. Intravenous administration should be restricted to emergency preoperative loading (single 500-mg dose); to patients with proven anaerobic infections; patients with serious sepsis associated with an unidentified organism; patients who are unable to take medication by mouth and those without a functional rectum or with diarrhoea; and patients with leukaemia who are vomiting. These drugs are remarkably safe under conditions of acute use if the intravenous route is avoided. However, extreme caution in their long-term use and use in obstetric and paediatric patients should be exercised until toxicological issues are resolved. It is concluded that the nitroimidazoles are effective, cheap and safe drugs for the short-term treatment of protozoal and bacterial (anaerobic) infections.