Pharm

Metronidazole

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Metronidazole, Flagyl

  • Mechanism
  1. Nitroimidazole antibiotic (includes tindazole, secnidazole)
  2. Inhibits Protein synthesis in susceptible organisms by disrupting DNA helix and resulting in DNA breakage
  • Indications
  1. Protozoal Infection
    1. Trichomoniasis
    2. Amebiasis
    3. Giardiasis
  2. Anaerobic Bacteria infection
    1. Bacteroides fragilis
    2. Clostridium difficile
    3. Bacterial Vaginosis
  • Precautions
  1. Carcinogenic in mice and rats (FDA Black box warning)
  • Pharmacokinetics
  1. Half-Life: 8 hours
  2. Renal excretion
  • Dosing
  • Children
  1. Dose
    1. Load: Metronidazole 15 mg/kg IV
    2. Maintenance: Metronidazole 7.5 mg/kg/dose
  2. Interval
    1. First week of life: q12 hours
    2. After first week of life: q 8hours
  • Dosing
  • Adult
  1. Intravenous
    1. Loading dose: 15 mg/kg up to 1000 mg IV
    2. Maintenance dose: 7.5 mg/kg up to 500 mg IV q6-8 hour
  2. Oral dose: 250 to 750 mg PO tid
  • Adverse Effects
  1. Disulfiram Effect (Antabuse Effect)
    1. Since the 1960s, Alcohol has been strictly cautioned against when taking Metronidazole
    2. More recent data suggests no inhibition of aldehyde dehydrogenase as is seen with Disulfiram
    3. Safest to avoid Alcohol with Metronidazole, but interactions appear to be very uncommon
    4. (2021) Presc Lett 28(10): 58
  2. Gastrointestinal intolerance
  3. Neurotoxicity (stop immediately if these occur)
    1. Seizures
    2. Encephalopathy
    3. Cerebellar dysfunction
    4. Peripheral Neuropathy (e.g. distal Paresthesias)
  • Pregnancy
  1. Class B Medication (Avoid in first trimester pregnancy)
  • Directions
  1. Taking with food decreases gastric irritation
  • References
  1. Burtin (1995) Am J Obstet Gynecol 172:525-9 [PubMed]