Metronidazol Polpharma (Metronidazole)

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

• Bacterial vaginosis: eliminates anaerobic bacteria to restore normal vaginal flora.
• Trichomoniasis: eradicates Trichomonas vaginalis, relieving symptoms and preventing recurrence.
• Amoebiasis: destroys Entamoeba histolytica trophozoites, treating intestinal and extra‑intestinal disease.
• Giardiasis: clears Giardia lamblia infection, reducing diarrhea and abdominal discomfort.
• Anaerobic bacterial infections: targets a broad range of anaerobes in intra‑abdominal, skin and dental infections.
• Clostridioides difficile infection: reduces toxin‑producing C. difficile, aiding resolution of moderate cases.

• Metronidazole enters susceptible anaerobic microorganisms by passive diffusion. Inside the cell, reduction of its nitro group by ferredoxin‑dependent enzymes generates reactive nitro radicals. These radicals interact with DNA, causing strand breakage and inhibiting nucleic acid synthesis, which leads to cell death. The selective activation in low‑oxygen environments accounts for its efficacy against anaerobic bacteria and protozoa.

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

Common Side Effects

• Nausea: mild stomach upset often occurring early in therapy.
• Metallic taste: transient metallic sensation in the mouth.
• Headache: mild to moderate headache during treatment.
• Diarrhea: loose stools that usually resolve after discontinuation.
• Vomiting: occasional episodes of emesis, usually self‑limited.

Serious or Rare Side Effects

• Peripheral neuropathy: tingling or numbness in extremities, potentially irreversible.
• Seizures: rare occurrence of convulsions, especially with high doses.
• Stevens‑Johnson syndrome: severe skin reaction with blistering and mucosal involvement.
• Hepatotoxicity: elevated liver enzymes indicating liver injury.
• Hypersensitivity reactions: rash, fever, or anaphylaxis in susceptible individuals.

When prescribing Metronidazole, clinicians should observe several precautionary measures to ensure safe use.

• Assess renal and hepatic function: adjust therapy in patients with impairment.
• Evaluate for history of neurological disorders: monitor for peripheral neuropathy.
• Avoid use in first trimester: consider alternative agents if pregnancy is possible.
• Review concomitant alcohol consumption: advise patients to abstain during and 48 hours after therapy.
• Monitor for superinfection: watch for overgrowth of non‑susceptible organisms.
• Store at ambient temperature: keep tablets in original container, protect from moisture and heat.

Metronidazole can interact with other medicines, affecting its efficacy or safety.

Major Interactions (Avoid)

• Alcohol: may cause a disulfiram‑like reaction with flushing, nausea and tachycardia.
• Warfarin: potentiates anticoagulant effect, increasing risk of bleeding.
• Lithium: may raise lithium levels, leading to toxicity.
• Phenobarbital: induces hepatic enzymes, lowering metronidazole concentrations.

Moderate Interactions (Monitor Closely)

• Cimetidine: can increase metronidazole plasma concentrations.
• Phenytoin: may reduce metronidazole levels, decreasing therapeutic effect.
• Oral contraceptives: may experience reduced efficacy; advise additional contraceptive measures.
• Baclofen: may increase central nervous system side effects; monitor patient.