IDStewardship

Metronidazole (Flagyl)

Oral metronidazole

IV metronidazole

KEY POINTS

  • Metronidazole (Flagyl) is an antimicrobial drug that works by interacting with DNA to interfere with the helical DNA structure/strands, which results in inhibition of protein synthesis and cell death for susceptible organisms
  • Has activity versus a variety of organisms, including Gram negative bacteria, Gram positive bacteria, and protozoa
    • An important drug for the management of infections caused by anaerobic bacteria
      • Utility of metronidazole for Clostridium difficile (a Gram positive anaerobe) has become less over time and it is no longer considered the drug of choice for mild-moderate disease
    • A common drug used for treatment of bacteria vaginosis (the most common vaginal infection in women 15 to 44 years of age)
    • A common drug used for treatment of trichomoniasis, the most common non-viral sexually transmitted infection in the United States
    • Also used for pelvic inflammatory disease, amoebic infections, Helicobacter pylori infections and more
  • In general is well tolerated, but…
    • Has a U.S. Black Box Warning for being “possibly carcinogenic based upon animal data”
    • Common to cause metallic taste and larger oral doses common to cause nausea
    • Long-term or repeated use has been associated with peripheral neuropathy
    • May also cause CNS effects (e.g., headache, aseptic meningitis, encephalopathy)
  • Beware disulfiram-like reaction with alcohol (generally recommend to avoid alcohol within 3 days of therapy)
    • Few drug-drug interactions overall
  • Commonly dosed 500mg every 12 or 8 hours
    • A common target for IV to PO conversion programs due to good bioavailability
    • Dose adjustment for renal function only necessary when significant impairment is present (and even this is debated)
    • Has an extended release tablet formulation available

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