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Drug Name: Metronidazole

Click on the titles below for drug details

  • Produce free radicals which causes DNA damage and degradation. Effective even against non-growing organisms despite interacting with DNA.
  • PO and IV
  • Taking with food minimizes stomach upset
  • Doses
    • General doses:
      • Oral: 7.5 mg/kg/dose every 8 hours, maximum daily dose: 2250 mg
      • IV: 7.5-10 mg/kg/dose every 8 hours; maximum daily dose: 1500 mg (rarely 2000 mg)
    • Decreased kidney function does not impact serum half-life but is associated with accumulation of metabolites with more severe impairment and prolonged courses resulting in potential for higher CNS side effects. Talk to your friendly pharmacist.
    • Requires hepatic adjustment in severe impairment, though single-dose regimens do not require dosage adjustment. Talk to your friendly pharmacist.
  • Dosage forms:
    • 500mg/5mL suspension
    • 250mg and 500mg tablet
    • 375mg capsule (less common)
  • Spectrum
    • Broad anaerobic Gram-positive and anaerobic Gram-negative activity
      • Gram-positive examples include Clostridium species
      • Gram-negative examples include Bacteroides, Fusobacterium, and H. pylori
    • Does NOT cover: Aerobes
  • Indications:
    • Often combined with cephalosporins for broad coverage of intraabdominal organisms
    • Entamoeba histolytica
    • Bacterial vaginosis: Typical adolescent dose is 500 mg PO BID x7 days
    • Clostridium difficile infection (note: enteral vancomycin is typically preferred)
      • 7.5 mg/kg/dose every 6-8 hours for 10 days (maximum dose 500 mg)
      • 10 mg/kg/dose every 8 hours for severe infection
    • Giardiasis - 5 mg/kg/dose every 8 hours for 5-7 days (maximum dose 250 mg/dose)
    • Intraabdominal infection (combination regimen), typically only requires 4-7 days after source control
      • 10 mg/kg/dose q8hrs
    • Pelvic Inflammatory Disease - Oral, IV: 500 mg q12 hours for 14 days
    • Intracranial infections (e.g., Epidural Abscess, Pott's Puffy Tumor)
  • Hypersensitivity to metronidazole or tinidazole
  • Use with caution in patients with hepatic impairment due to risk of accumulation
  • Use with caution in patients with seizure disorders given risk of CNS side effects
  • CNS side effects including seizures, encephalopathy, aseptic meningitis, neuropathy, headache, and dizziness
  • Harmless brown discoloration of urine
  • Disulfiram-like reaction (abdominal pain, nausea, vomiting, headaches, flushing) when administered with alcohol up to 3 days after discontinuation.
  • Rare bone marrow suppression (neutropenia, thrombocytopenia)
  • Nausea, vomiting, diarrhea
  • Vaginitis
  • Excellent bioavailability, including in the CSF (concentrations similar to those in plasma)
  • Take with food to minimize GI upset
  • Disulfiram-like reaction, especially for adolescents and young adults who may drink alcohol
  • Discoloration of urine
  • CNS side effects: headache, dizziness, confusion (encephalopathy), neck pain (aseptic meningitis), seizures