Pharm 101: Metronidazole

Class

Nitroimidazole antiprotozoal drug


Pharmacodynamics
  • Selectively absorbed by anaerobic bacteria and sensitive protozoa
  • Causes disruption of electron transport chain

Pharmacokinetics
  • PO/IV/suppository administration
  • Well absorbed
  • 99% bioavailability
  • Low protein binding 10-20%
  • Well distributed in tissues, including CSF
  • Hepatic metabolism
  • Renal excretion
    • Half-life 7.5 hours

Antimicrobial activity
  • Potent activity against anaerobes, including Bacteroides and Clostridium species
  • Clinical uses:
    • Anaerobic or mixed intra-abdominal infections
    • Vaginitis
    • Clostriudium difficile
    • Brain abscess

Adverse effects
  • Gastrointestinal
    • Nausea
    • Diarrhoea
    • Stomatitis
  • Neurological:
    • Headache
    • Metallic taste in mouth
    • Peripheral neuropathy with prolonged use
  • Thrombophlebitis
  • Disulfiram-like effect, therefore avoid alcohol
    • Inhibits aldehyde dehydrogenase and causes accumulation of acetaldehyde in blood
  • Inhibitions CYP 3A4 (responsible for metabolism of 50% of drugs)
    • Potentiates effect of warfarin

Precautions/contraindications
  • Hepatic insufficiency or renal failure require dose adjustment

References

Pharm 101 700

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU Emergency Medicine Trainee with interests in medical education, ECG interpretation, and the use of point-of-care ultrasound in the undifferentiated patient. Co-author of the LITFL ECG Library | Twitter

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