Metronidazole Noridem (Metronidazole)

Metronidazole is indicated for a range of anaerobic and protozoal infections.

• Anaerobic bacterial infections: eradicates susceptible anaerobes causing intra‑abdominal and soft‑tissue infections.
• Bacterial vaginosis: restores normal vaginal flora by eliminating Gardnerella and related organisms.
• Trichomoniasis: eliminates Trichomonas vaginalis, relieving symptoms and preventing transmission.
• Intra‑abdominal infections: provides systemic coverage for mixed aerobic‑anaerobic peritonitis and abscesses.
• Pelvic inflammatory disease: treats polymicrobial PID where anaerobes are implicated.

• Metronidazole enters susceptible anaerobic bacteria and protozoa, where intracellular reduction of its nitro group generates reactive nitro radicals. These radicals cause DNA strand breakage and inhibit nucleic acid synthesis, leading to loss of cell viability and bacterial or protozoal death.

Metronidazole may cause a variety of adverse reactions, ranging from mild to severe.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Metallic taste: transient dysgeusia during infusion.
• Headache: mild, often resolves without intervention.
• Diarrhea: loose stools, usually self‑limited.
• Skin rash: mild erythema or pruritus.

Serious or Rare Side Effects

• Seizures: rare neurotoxic events, especially with high plasma levels.
• Peripheral neuropathy: tingling or numbness with prolonged therapy.
• Severe allergic reaction: anaphylaxis or Stevens‑Johnson syndrome.
• Hepatotoxicity: elevated liver enzymes or jaundice.
• Hematologic abnormalities: neutropenia or thrombocytopenia.

Metronidazole requires careful use in specific clinical situations.

• Pregnancy: Category B – generally considered safe, but use only if clearly needed.
• Breastfeeding: Small amounts excreted in milk; weigh benefits against potential infant exposure.
• Alcohol interaction: Avoid alcohol during and for 48 hours after therapy to prevent disulfiram‑like reaction.
• Renal or hepatic impairment: Dose may need adjustment; monitor function.
• Drug‑induced neuropathy: Limit duration when possible; monitor for sensory changes.
• Store below 25°C: keep in original container, protect from light and moisture.

Metronidazole can affect or be affected by several concomitant medicines.

Major Interactions (Avoid)

• Disulfiram: concurrent use can cause severe flushing, tachycardia, and hypotension.
• Warfarin: increased anticoagulant effect may raise bleeding risk.
• Lithium: may raise serum lithium levels, risking toxicity.

Moderate Interactions (Monitor Closely)

• Cimetidine: may raise metronidazole plasma concentrations.
• Phenobarbital or phenytoin: may reduce metronidazole efficacy by increasing metabolism.
• Alcohol: can precipitate a disulfiram‑like reaction; advise abstinence.