Metronidazole Milpharm (Metronidazole)

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

• Bacterial vaginosis: restores normal vaginal flora by eliminating anaerobic bacteria.
• Trichomoniasis: eradicates Trichomonas vaginalis infection, relieving symptoms.
• Amoebiasis: treats intestinal Entamoeba histolytica infection, preventing dysentery.
• Anaerobic infections: combats mixed anaerobic infections in intra‑abdominal, pelvic and soft‑tissue sites.

• Metronidazole enters susceptible microorganisms by passive diffusion. Inside the cell, reduction of its nitro group by ferredoxin‑type proteins generates reactive nitro radicals. These metabolites bind to DNA, causing strand breakage and inhibition of nucleic acid synthesis, ultimately leading to cell death of anaerobic bacteria and protozoa. The drug is selectively activated under low‑oxygen conditions, which limits toxicity to host cells and concentrates its effect on anaerobic pathogens.

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

Common Side Effects

• Nausea: occasional upset stomach or feeling sick.
• Metallic taste: a transient metallic sensation in the mouth.
• Headache: mild to moderate head pain.
• Abdominal pain: cramping or discomfort in the stomach area.
• Diarrhea: loose stools occurring during therapy.
• Loss of appetite: reduced desire to eat.

Serious or Rare Side Effects

• Seizures: convulsions requiring immediate medical attention.
• Peripheral neuropathy: tingling, numbness, or burning sensations in extremities.
• Severe allergic reactions: rash, Stevens‑Johnson syndrome, or anaphylaxis.
• Hepatotoxicity: liver enzyme elevations or hepatitis.
• Neutropenia: low white‑blood‑cell count increasing infection risk.
• Pseudomembranous colitis: severe colonic inflammation caused by Clostridioides difficile.

Before initiating therapy, consider the following safety measures.

• Assess renal and hepatic function: adjust therapy in patients with impairment.
• Avoid alcohol: concurrent intake may cause a disulfiram‑like reaction.
• Monitor for neurological symptoms: report numbness or tingling promptly.
• Use with caution in pregnancy: only if benefits outweigh risks.
• Inform patients about possible metallic taste and gastrointestinal upset.
• Store at below 25°C: keep in the original container, protect from moisture and light.

Metronidazole can interact with several medicines; awareness helps prevent adverse outcomes.

Major Interactions (Avoid)

• Alcohol: may cause severe nausea, vomiting, flushing, and hypotension.
• Warfarin: potentiates anticoagulant effect, increasing INR and bleeding risk.
• Lithium: may raise lithium concentrations, leading to toxicity.

Moderate Interactions (Monitor Closely)

• Cimetidine: may increase metronidazole plasma concentrations.
• Phenobarbital: may reduce metronidazole levels, decreasing efficacy.
• Oral contraceptives: may reduce hormonal effectiveness; advise backup contraception.