Metronidazole Cooper (Metronidazole)

Metronidazole is a nitroimidazole antibiotic used to manage infections caused by anaerobic bacteria and certain protozoa.

• Bacterial vaginosis: effective treatment of bacterial vaginosis in women.
• Trichomoniasis: eradicates Trichomonas vaginalis infection.
• Anaerobic intra‑abdominal infections: resolves intra‑abdominal and pelvic inflammatory disease caused by anaerobes.
• Clostridioides difficile infection: used as part of therapy for C. difficile‑associated colitis.
• Skin and soft tissue infections: treats anaerobic skin and soft‑tissue infections.

• Metronidazole enters susceptible anaerobic cells by passive diffusion and is reduced by intracellular redox proteins to reactive nitro radicals. These metabolites bind to DNA, causing strand breakage and inhibition of nucleic acid synthesis, ultimately leading to bacterial cell death. The drug’s selective activation in low‑oxygen environments accounts for its activity against anaerobic bacteria and protozoa.

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

Common Side Effects

• Nausea: mild to moderate upset stomach.
• Metallic taste: transient metallic sensation in the mouth.
• Headache: occasional mild headache.

Serious or Rare Side Effects

• Seizures: rare neurologic event requiring immediate attention.
• Peripheral neuropathy: tingling or numbness in extremities.
• Severe allergic reactions: including rash, itching, swelling, or anaphylaxis.

When using Metronidazole, several safety considerations should be observed to minimize risk.

• Renal impairment: assess renal function and adjust therapy if necessary.
• Hepatic impairment: use with caution in patients with liver disease.
• Alcohol consumption: avoid alcohol during treatment and for at least 48 hours after the last dose to prevent a disulfiram‑like reaction.
• Pregnancy: safety not established; reserve for situations where benefits outweigh potential risks.
• Concurrent warfarin therapy: monitor INR closely due to possible enhanced anticoagulant effect.
• Store at below 25°C: keep in original container, protect from moisture and light.

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

Major Interactions (Avoid)

• Alcohol: may cause a disulfiram‑like reaction.
• Warfarin: can increase anticoagulant effect and bleeding risk.
• Lithium: may raise lithium levels and toxicity.

Moderate Interactions (Monitor Closely)

• Cimetidine: may increase metronidazole plasma concentrations.
• Phenobarbital: may reduce metronidazole levels, decreasing efficacy.
• Phenytoin: may lower metronidazole concentrations, requiring monitoring.