Metronidazol Aristo (Metronidazole)

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

• Bacterial vaginosis: restores normal vaginal flora by eliminating anaerobic bacteria.
• Trichomoniasis: eradicates Trichomonas vaginalis, relieving symptoms and preventing transmission.
• Amoebiasis: destroys Entamoeba histolytica trophozoites, treating intestinal and extra‑intestinal disease.
• Anaerobic bacterial infections: clears infections such as intra‑abdominal, skin, and pelvic infections caused by susceptible anaerobes.
• Clostridioides difficile infection: reduces toxin‑producing C. difficile, aiding resolution of moderate to severe colitis.

• Metronidazole is a pro‑drug that, after entering susceptible microorganisms, is reduced by ferredoxin‑type proteins to generate nitro radical anions. These reactive intermediates interact with DNA, causing strand breakage and loss of helical structure, and also inhibit nucleic acid synthesis, leading to cell death of anaerobic bacteria and protozoa. The reduction process is selective for low‑oxygen environments, which explains the drug’s activity against anaerobes while sparing most aerobic cells.

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.
• Diarrhea: loose stools that usually resolve after treatment ends.
• Headache: mild to moderate headache during the course.
• Abdominal cramps: intermittent stomach cramps.
• Dark urine: discoloration of urine, generally harmless.

Serious or Rare Side Effects

• Peripheral neuropathy: tingling or numbness in extremities, potentially irreversible if prolonged.
• Seizures: rare occurrence of convulsions, requiring immediate medical attention.
• Severe allergic reaction: rash, itching, swelling, or anaphylaxis.

Before prescribing Metronidazole, clinicians should consider several precautionary measures to ensure safe use.

• Assess renal function: dose adjustment may be needed in severe renal impairment.
• Evaluate hepatic status: monitor liver enzymes in patients with liver disease.
• Avoid alcohol: concurrent alcohol can cause a disulfiram‑like reaction with flushing and tachycardia.
• Use caution in pregnancy: weigh benefits against potential risks, especially in the first trimester.
• Monitor for neurotoxicity: watch for signs of peripheral neuropathy during prolonged therapy.
• Store at ambient temperature: keep below 25 °C in the original container, protect from moisture.

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

Major Interactions (Avoid)

• Alcohol: may precipitate a severe disulfiram‑like reaction with nausea and cardiovascular symptoms.
• Warfarin: can enhance anticoagulant effect, increasing risk of bleeding.
• Lithium: may raise lithium levels, leading to toxicity.

Moderate Interactions (Monitor Closely)

• Cimetidine: may increase metronidazole plasma concentrations.
• Phenytoin: may reduce metronidazole levels, decreasing therapeutic effect.
• Oral contraceptives: may slightly reduce contraceptive efficacy, advise additional protection.