Metronidazol Generis (Metronidazole)

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

• Anaerobic bacterial infections: eradicates susceptible anaerobes in intra‑abdominal, pelvic, and soft‑tissue infections.
• Bacterial vaginosis: restores normal vaginal flora by eliminating Gardnerella and other anaerobic organisms.
• Trichomoniasis: eliminates Trichomonas vaginalis, relieving symptoms and preventing transmission.
• Amebic liver abscess: destroys Entamoeba histolytica trophozoites, aiding resolution of hepatic lesions.
• Intra‑abdominal infections: provides coverage for mixed aerobic‑anaerobic flora in peritonitis and postoperative infections.
• Pelvic inflammatory disease: treats anaerobic components of PID, reducing inflammation and complications.

• Metronidazole enters susceptible microorganisms by passive diffusion. Inside anaerobic cells, its nitro group is reduced to reactive nitro radicals that bind to DNA, causing strand breakage and inhibition of nucleic acid synthesis. The resulting damage prevents bacterial replication and leads to cell death, while aerobic cells are less affected due to efficient oxidation of the drug. Thus, the drug exhibits selective toxicity toward anaerobes and certain protozoa.

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

Common Side Effects

• Nausea: mild to moderate nausea may occur during therapy.
• Metallic taste: a transient metallic sensation in the mouth is frequently reported.
• Headache: mild headache can develop, especially with higher infusion rates.
• Diarrhea: loose stools may appear, usually self‑limiting.
• Abdominal pain: crampy abdominal discomfort is occasionally observed.
• Skin rash: mild erythematous rash may develop.

Serious or Rare Side Effects

• Seizures: rare central nervous system toxicity can precipitate seizures.
• Peripheral neuropathy: prolonged use may lead to sensory neuropathy, sometimes irreversible.
• Severe allergic reactions: anaphylaxis or Stevens‑Johnson syndrome may occur.
• Hepatic toxicity: elevated liver enzymes or hepatitis have been reported.
• Neutropenia: significant reduction in white blood cells can develop.
• Disulfiram‑like reaction: flushing, tachycardia, and hypotension after alcohol intake.

Before initiating Metronidazol Generis, clinicians should consider several safety precautions.

• Assess renal function: adjust dosing in patients with impaired kidney clearance.
• Monitor hepatic status: use cautiously in liver disease and watch liver enzymes.
• Evaluate alcohol use: avoid concomitant alcohol to prevent disulfiram‑like reactions.
• Review pregnancy status: although Category B, weigh benefits against potential risks.
• Check for hypersensitivity: discontinue if signs of severe allergic reaction appear.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Metronidazol Generis can interact with several medicines, altering efficacy or safety.

Major Interactions (Avoid)

• Alcohol: may cause severe disulfiram‑like reaction with flushing and hypotension.
• Lithium: concurrent use can increase lithium levels, risking toxicity.
• Warfarin: metronidazole may potentiate anticoagulant effect, raising bleeding risk.
• Cyclosporine: increased neurotoxicity has been reported when combined.

Moderate Interactions (Monitor Closely)

• Phenytoin: may reduce metronidazole plasma concentrations, decreasing effectiveness.
• Carbamazepine: enzyme induction can lower metronidazole levels.
• Rifampin: may decrease metronidazole exposure, requiring clinical monitoring.