Metronidazole B Braun (Metronidazole)

Metronidazole is used to manage infections caused by anaerobic bacteria and certain protozoa.

• Anaerobic bacterial infections: reduces bacterial load and improves clinical symptoms in mixed anaerobic infections.
• Clostridioides difficile infection: eradicates toxin‑producing C. difficile, aiding resolution of colitis.
• Bacterial vaginosis: restores normal vaginal flora by eliminating anaerobic overgrowth.
• Trichomoniasis: eliminates Trichomonas vaginalis, relieving genital symptoms.
• Amebic liver abscess: destroys Entamoeba histolytica trophozoites, facilitating abscess resolution.

• Metronidazole enters anaerobic cells and is reduced by ferredoxin‑type proteins to reactive nitro radicals. These radicals interact with DNA, causing strand breakage and loss of helical structure, and also inhibit nucleic acid synthesis. The resulting damage leads to bacterial or protozoal cell death, while aerobic cells are largely unaffected due to lack of reduction.

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

Common Side Effects

• Nausea: mild to moderate upset stomach.
• Metallic taste: transient metallic sensation in the mouth.
• Headache: occasional throbbing headache.
• Diarrhea: loose stools during therapy.
• Abdominal pain: cramping or discomfort.
• Dizziness: light‑headed feeling.

Serious or Rare Side Effects

• Seizures: rare neurologic events requiring immediate care.
• Peripheral neuropathy: tingling or numbness in extremities.
• Severe allergic reactions: anaphylaxis, rash, or swelling.
• Stevens‑Johnson syndrome: serious skin eruption.
• Hepatic dysfunction: elevated liver enzymes or hepatitis.
• Neutropenia: reduced white blood cell count increasing infection risk.

Metronidazole requires careful use in specific patient groups and conditions.

• Renal impairment: adjust dosing and monitor renal function.
• Hepatic impairment: use with caution; monitor liver enzymes.
• Alcohol consumption: avoid during and 48 hours after therapy to prevent disulfiram‑like reaction.
• Pregnancy and lactation: assess risk–benefit; limited safety data available.
• Concurrent anticoagulants: monitor coagulation parameters for enhanced effect.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Metronidazole can interact with several medicines, altering efficacy or safety.

Major Interactions (Avoid)

• Alcohol: may cause severe disulfiram‑like reaction.
• Warfarin: increased anticoagulant effect; monitor INR closely.
• Lithium: elevated lithium levels; monitor for toxicity.

Moderate Interactions (Monitor Closely)

• Phenytoin: may reduce metronidazole plasma concentrations.
• Cimetidine: may increase metronidazole levels, enhancing side effects.
• Phenobarbital: may decrease metronidazole efficacy through enzyme induction.