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
- Katzung BG. Basic and Clinical Pharmacology. 14e. 2018: 895-896, 929-930
Pharmacology 101
Top 200 drugs
Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Co-creator of the LITFL ECG Library. Twitter: @rob_buttner