Metronidazolo S.A.L.F. (Metronidazole)

Metronidazole is indicated for a range of anaerobic and protozoal infections.

• Anaerobic bacterial infections: effective against mixed anaerobic infections, reducing bacterial load.
• Bacterial vaginosis: restores normal vaginal flora by eliminating pathogenic anaerobes.
• Trichomoniasis: eradicates Trichomonas vaginalis, relieving symptoms and preventing recurrence.
• Intra‑abdominal infections: controls polymicrobial infections following surgery or perforation.
• Pelvic inflammatory disease: targets anaerobic organisms contributing to pelvic inflammation.
• Bacterial sepsis: used as part of combination therapy for severe systemic infections caused by susceptible anaerobes.

• Metronidazole enters anaerobic microorganisms and undergoes reduction of its nitro group, generating reactive nitro radicals. These free radicals damage DNA, inhibit nucleic acid synthesis, and disrupt essential metabolic pathways, leading to bacterial cell death while sparing most aerobic cells.

Metronidazole may cause a range of adverse reactions.

Common Side Effects

• Nausea: mild to moderate upset stomach.
• Metallic taste: transient alteration of taste perception.
• Headache: occasional mild to moderate headache.
• Diarrhea: loose stools, usually self‑limiting.
• Abdominal pain: cramping or discomfort in the stomach area.
• Dizziness: occasional light‑headed sensation.

Serious or Rare Side Effects

• Seizures: rare neurologic events, especially with high doses.
• Peripheral neuropathy: tingling or numbness in extremities.
• Severe allergic reactions: anaphylaxis, rash, or swelling.
• Stevens‑Johnson syndrome: severe skin and mucous membrane reaction.
• Hepatic dysfunction: elevated liver enzymes or hepatitis.
• Neutropenia: marked reduction in white blood cells.

Metronidazole requires careful clinical monitoring in several situations.

• Renal impairment: adjust dosing and monitor renal function.
• Hepatic dysfunction: use with caution and observe liver enzymes.
• Alcohol consumption: avoid due to disulfiram‑like reaction.
• Pregnancy: safety not established; weigh maternal benefits against potential fetal risk.
• Concurrent warfarin therapy: monitor INR closely for increased anticoagulant effect.
• Store at room temperature: keep in original container, protect from light and moisture.

Metronidazole interacts with several medicines; some require avoidance, others close monitoring.

Major Interactions (Avoid)

• Alcohol: may cause severe disulfiram‑like reaction.
• Warfarin: may potentiate anticoagulant effect, increasing INR.
• Lithium: may raise lithium concentrations, risking toxicity.
• Cimetidine: may increase metronidazole plasma levels.
• Phenobarbital: may reduce metronidazole efficacy.

Moderate Interactions (Monitor Closely)

• Erythromycin: may increase risk of neurotoxicity.
• Ciprofloxacin: may raise seizure risk.
• Phenytoin: may lower metronidazole plasma concentrations.