Metronidazole B. Braun (Metronidazole)

Metronidazole is employed to manage infections caused by anaerobic bacteria and susceptible protozoa.

• Anaerobic bacterial infections: effective against infections caused by anaerobic organisms, reducing bacterial load.
• Bacterial vaginosis: restores normal vaginal flora by eliminating pathogenic anaerobes.
• Trichomoniasis: eradicates Trichomonas vaginalis, relieving symptoms and preventing transmission.
• Intra‑abdominal infections: controls polymicrobial infections within the abdominal cavity.
• Pelvic inflammatory disease: targets anaerobic pathogens contributing to pelvic infection.
• Skin and soft tissue infections: treats infected wounds where anaerobes are present.

• Metronidazole enters anaerobic microorganisms and is reduced by cellular ferredoxin proteins to reactive nitro radicals. These radicals damage DNA, inhibit nucleic acid synthesis, and disrupt essential metabolic pathways, leading to irreversible cell death of susceptible bacteria and protozoa.

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

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Metallic taste: transient metallic sensation in the mouth.
• Headache: mild to moderate headache.
• Diarrhea: loose stools, usually self‑limiting.
• Abdominal pain: cramping or discomfort.
• Dizziness: occasional light‑headedness.

Serious or Rare Side Effects

• Seizures: rare neurologic events requiring immediate care.
• Peripheral neuropathy: tingling or numbness in extremities.
• Stevens‑Johnson syndrome: severe skin reaction with blistering.
• Anaphylaxis: life‑threatening allergic response.
• Severe liver injury: marked elevation of hepatic enzymes.
• Neutropenia: significant drop in white blood cell count.

Metronidazole requires careful monitoring in specific clinical situations.

• Renal function assessment: adjust therapy in patients with impaired kidney function.
• Hepatic monitoring: observe liver enzymes during prolonged treatment.
• Alcohol avoidance: prevent disulfiram‑like reactions by abstaining from alcohol.
• Pregnancy considerations: use only if benefits outweigh potential risks, as safety data are limited.
• Elderly patients: start with lower doses and monitor for toxicity.
• 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 flushing, tachycardia, and hypotension.
• Warfarin: can enhance anticoagulant effect, increasing bleeding risk.
• Lithium: may raise lithium levels, leading to toxicity.

Moderate Interactions (Monitor Closely)

• Carbamazepine: may reduce metronidazole plasma concentrations.
• Oral contraceptives: efficacy may be decreased, consider alternative contraception.