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Author: Vanessa Ngan, Staff Writer, 2005.
Metronidazole is an imidazole antibiotic that is used in the treatment of many protozoal and bacterial infections. It is available on prescription in various forms and strengths, including tablets, suspensions, solutions for injections, suppositories and topical creams and gels.
For skin conditions, topical metronidazole is indicated for the treatment of facial rosacea. In New Zealand topical metronidazole is a prescription medicine and is available as a 7.5 mg/g aqueous gel and cream (Rozex®) or a 5% generic gel. A foam preparation was also approved by the FDA and marked in the USA in July 2015.
A vaginal gel preparation of metronidazole is also available in some countries to treat bacterial vaginosis.
Metronidazole is an antiprotozoal and anaerobic antibacterial agent. When administered systemically via oral tablets or injection, metronidazole works by inhibiting bacterial DNA synthesis hence preventing the replication of bacteria. However, the mechanisms by which topical metronidazole works in reducing inflammatory lesions of rosacea are unknown. Possible mechanisms of action include antibacterial and/or anti-inflammatory effects.
Topical metronidazole is indicated for the treatment of inflammatory papules, pustules and erythema of rosacea. It should be applied twice daily, morning and evening, to the affected area after washing with a mild cleanser and patting dry. The average period of treatment is 3-4 months, although some improvement should be noticeable after 3 weeks of continued therapy. If significant improvement is seen after 3-4 months, your doctor may prescribe a further 3-4 months therapy. Treatment should be stopped if no clear clinical improvement is evident after the first 3-4 months.
Side effects from the use of topical metronidazole are rare and usually mild. Side effects that should be reported to your doctor as soon as possible include:
Other possible side effects that should resolve after continued use of topical metronidazole include:
If you are not based in New Zealand, we suggest you refer to your national drug approval agency for further information about medicines (eg, the Australian Therapeutic Goods Administration and the US Food and Drug Administration) or a national or state-approved formulary (eg, the New Zealand Formulary and New Zealand Formulary for Children and the British National Formulary and British National Formulary for Children).
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