Metronidazole Flashcards
What drug class does metronidazole belong to?
Drug Class: nitroimidazole
What is the MOA of metronidazole?
Metronidazole is metabolised to active metabolites that are thought to interfere with DNA synthesis.
What are the indications for metronidazole use?
Anaerobic bacterial infections, eg B. fragilis
Protozoal infections, eg giardiasis, trichomoniasis
Clostridium difficile-associated disease
Dental infections, including acute gingivitis
Bacterial vaginosis
PID
Amoebiasis (intestinal and extra-intestinal)
Surgical prophylaxis
Eradication of H. pylori (as part of a multidrug regimen
Rosacea
Fungating wounds
What are the precautions for metronidazole use?
- Treatment with disulfiram - combination may cause psychotic reactions
- Treatment with fluorouracil - avoid combination (increases fluorouracil concentration)
- Cockayne syndrome
- Renal
- Hepatic
- History of CNS disorders (including seizures) —nitroimidazoles are neurotoxic and may aggravate existing neurological disease.
- History of blood dyscrasias - may cause leucopenia
What is the precaution surrounding metronidazole and treatment with disulfiram?
Treatment with disulfiram—combination may cause psychotic reactions; do not use metronidazole within 2 weeks of disulfiram.
What is the renal precaution surrounding metronidazole use?
Metabolites may accumulate in severe impairment possibly causing adverse effects. Dose adjustment is not usually necessary.
What is the hepatic precaution surrounding metronidazole?
Risk of drug accumulation and toxicity in severe impairment, especially if renal impairment is also present; reduce dose.
Is metronidazole safe in pregnancy or breastfeeding?
Safe to use in pregnancy (take in divided doses if possible)
Safe to use in breastfeeding. May cause some bitterness in milk. Use in divided doses after breastfeeding rather than single daily doses.
What are the common adverse effects of metronidazole?
nausea anorexia abdominal pain vomiting diarrhoea metallic taste CNS effects, eg dizziness, headache (frequencies may depend on whether a single large dose is given)
What are some rare adverse effects of metronidazole?
- Clostrudium difficile-associated disease
Are there any high dose &/or prolonged treatment adverse effects?
Leucopenia is reversible and usually only occurs after prolonged treatment; peripheral neuropathy (usually reversible) and/or CNS toxicity (eg seizures, encephalopathy, cerebellar toxicity) are more likely.
What is leucopenia?
Low white blood cell count.
Leucopenia is a decrease in the number of white blood cells, which puts a person at risk for infection. Normally when a person has infection or inflammation, the number of white blood cells increases so there are more cells to fight the infection with.
What is the adult dosage range of metronidazole?
Adult
Oral, 200–400 mg every 8–12 hours, up to 4 g daily.
Rectal, 1 g every 8–12 hours.
Severe infections
IV, 500 mg every 8–12 hours as part of multidrug regimen. Maximum 4 g daily.
What is the metronidazole treatment regimen for clostridium difficle-associated disease?
Oral
Adult, oral 400 mg every 8 hours for 10 days.
Child, oral 10 mg/kg (maximum 400 mg) every 8 hours for 10 days.
IV
Give IV if unable to tolerate oral treatment, or with vancomycin in severe disease.
Adult, IV 500 mg every 8 hours for 10 days.
Child, IV 12.5 mg/kg (maximum 500 mg) every 8 hours for 10 days.
What is the metronidazole treatment regimen for bacterial vaginosis?
Adult, oral 400 mg twice daily for 7 days
