Metronidazole B. Braun Melsungen (Metronidazole)

Metronidazole is indicated for infections caused by anaerobic bacteria and certain protozoa.

• Anaerobic bacterial infections: eradicates susceptible anaerobes in mixed or pure infections.
• Bacterial vaginosis: restores normal vaginal flora by eliminating Gardnerella species.
• Trichomoniasis: eliminates Trichomonas vaginalis, relieving symptoms.
• Intra‑abdominal infections: treats peritonitis and abscesses involving anaerobic organisms.

• Metronidazole is reduced by anaerobic microorganisms to reactive nitro radicals that damage DNA and inhibit nucleic acid synthesis, leading to bacterial cell death. The drug selectively targets low‑oxygen environments, sparing aerobic cells and providing a focused antimicrobial effect.

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 or increased bowel movements.
• Abdominal pain: cramping or discomfort.
• Dizziness: light‑headed feeling.

Serious or Rare Side Effects

• Seizures: rare neurologic events.
• Peripheral neuropathy: tingling or numbness in extremities.
• Severe allergic reactions: anaphylaxis, rash, or swelling.
• Stevens‑Johnson syndrome: severe skin blistering.
• Hepatic dysfunction: elevated liver enzymes or hepatitis.
• Neutropenia: reduced white blood cell count.

Before initiating therapy, consider the following safety measures.

• Assess renal function: adjust therapy if renal impairment is present.
• Monitor hepatic enzymes: watch for liver toxicity during prolonged use.
• Avoid alcohol: prevent disulfiram‑like reactions.
• Use with caution in pregnancy: risk unknown, weigh benefits against potential harm.
• Adjust dose in hepatic impairment: consider reduced dosing.
• Store at below 25°C: keep in the original pack, protect from moisture and light.

Metronidazole can interact with several medications, requiring careful management.

Major Interactions (Avoid)

• Alcohol: may cause severe flushing and tachycardia.
• Warfarin: potentiates anticoagulant effect, increasing bleeding risk.
• Lithium: may increase lithium toxicity.
• Cyclosporine: elevated cyclosporine concentrations.
• Phenytoin: reduces metronidazole plasma levels.

Moderate Interactions (Monitor Closely)

• Cimetidine: increases metronidazole exposure.
• Carbamazepine: may lower metronidazole efficacy.
• Rifampin: reduces metronidazole concentrations.
• Oral contraceptives: may decrease contraceptive effectiveness.
• Theophylline: raises theophylline levels, risking toxicity.