Metronidazole
Class: antibiotic – anti-anaerobe
Indications (NB some may be unlicensed): anaerobic bacterial infections, useful in controlling malodorous wounds
Contraindications/cautions: hypersensitivity to nitroimidazoles such as ornidazole; caution in renal & hepatic impairment
Adverse reactions: common: GI upset (abdominal pain, nausea, vomiting, diarrhoea), urticaria, metallic taste, furry tongue; less common: QT prolongation, drowsiness, headache, dizziness, urine darkening, blood disorders, muscle/joint pain
Metabolism/clearance: metabolised in the liver to some active and some inactive metabolites which are excreted with some parent drug by the kidneys
Interactions:
- disulfiram-like reaction (nausea, vomiting, sweating) may occur with concomitant alcohol
- increased toxicity of lithium may occur with metronidazole
- Metronidazole can increase INR in patients on warfarin
- Increased plasma concentrations of cyclosporin, fluorouracil, phenytoin
| Dosing: | |
|---|---|
| oral: | 800 mg stat then 400 mg 3 times a day |
| subcut: | injection available but not usually used subcut |
| iv: | 500 mg 3 times a day (infusion) |
| rectal: | 1 g 3 times a day for 3 days then twice a day |
| topical: | apply twice a day |
Syringe driver: not applicable
Mechanism of action: in malodorous wounds kills anaerobes responsible for the smell
Topical use:
- useful for malodourous wounds
- availability of 0.75% gel limited in NZ and not funded
- tablets can be crushed finely and applied to wound in lubricating gel or as a powder