Metronidazole Mercury Pharmaceuticals Limited (Metronidazole)

Metronidazole is a nitroimidazole antibiotic indicated for several anaerobic and protozoal infections.

• Bacterial vaginosis: restores normal vaginal flora and relieves discharge.
• Trichomoniasis: eradicates Trichomonas vaginalis and resolves genital irritation.
• Amoebiasis: eliminates intestinal Entamoeba histolytica and prevents tissue invasion.
• Clostridioides difficile infection: reduces toxin‑producing bacterial load in the colon.
• Anaerobic bacterial infections: targets a broad range of anaerobes in intra‑abdominal, pelvic, and soft‑tissue sites.

• Metronidazole enters susceptible anaerobic cells and is reduced by intracellular electron transport proteins, generating nitro radicals. These reactive intermediates damage DNA, inhibit nucleic acid synthesis, and disrupt bacterial and protozoal replication, leading to cell death without affecting most aerobic organisms.

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: dull or throbbing head pain.
• Diarrhea: loose stools, sometimes watery.
• Skin rash: mild erythema or itching.
• Dark urine: harmless discoloration of urine.

Serious or Rare Side Effects

• Peripheral neuropathy: tingling or numbness in extremities.
• Seizures: rare convulsive episodes.
• Severe allergic reaction: hives, swelling, or difficulty breathing.
• Hepatotoxicity: elevated liver enzymes or jaundice.
• Stevens‑Johnson syndrome: severe skin blistering.
• Hematologic abnormalities: low white blood cell or platelet counts.

Metronidazole should be used with caution in specific clinical situations.

• Renal impairment: monitor renal function and adjust therapy if needed.
• Hepatic disease: use carefully; liver function tests may be required.
• Alcohol consumption: avoid alcohol during treatment and for 48 hours after to prevent disulfiram‑like reaction.
• Pregnancy: safety not established; weigh benefits against potential risks.
• Breastfeeding: consider infant exposure; consult a healthcare professional.
• Storage: Store at 2‑8 °C: keep refrigerated, protect from light, do not freeze.

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

Major Interactions (Avoid)

• Disulfiram: may cause severe flushing, tachycardia, and hypotension.
• Warfarin: increased anticoagulant effect, risk of bleeding.
• Lithium: elevated lithium levels, potential toxicity.

Moderate Interactions (Monitor Closely)

• Cimetidine: may raise metronidazole plasma concentrations.
• Phenytoin: may reduce phenytoin levels, decreasing seizure control.
• Alcoholic beverages: can intensify disulfiram‑like reaction.