Metronidazole

Question 1

What are the common indications for metronidazole?

Answer 1

1) Antibiotic-associated colitis - C.diff
2) Oral infections or aspiration pneumonia
3) Surgical and gynaecological infections
4) Protozoal infections

Question 2

what is the spectrum of activity of metronidazole?

Answer 2

Anaerobic bacteria and protozoa

Question 3

what is the MoA of metronidazole?

Answer 3

Bactericidal- Binds to DNA → disrupts helix → inhibits bacterial nucleic acid synthesis

Question 4

outline the important side effects caused by metronidazole

Answer 4

1) GI upset and hypersensitivity reactions
2) high doses or prolonged use can cause neurological adverse effects, including peripheral and optic neuropathy, seizures and encephalopathy
3) Taste disturbance, Furred tongue, Oral mucositis

Question 5

who should metronidazole be used in caution with?

Answer 5

1) Hepatically metabolised reduce dose in severe liver disease
2) inhibits the enzyme acetaldehyde dehydrogenase. avoid alcohol as this can cause ‘disulfiram-like’ reaction, including flushing, headache, nausea and vomiting.

Question 6

outline some of the important interactions with regards to metronidazole

Answer 6

1) some inhibitory effect on CYP, reducing metabolism of warfarin ( risk of bleeding) and phenytoin
2) with CYP inducers (e.g. phenytoin, rifampicin), reduced plasma concentrations of metronidazole
3) increases the risk of toxicity with lithium

Question 7

how long should alcohol be avoided after metronidazole treatement?

Answer 7

48 hours

Question 8

what are the monitoring requirements for metronidazole?

Answer 8

For treatment exceeding 10 days, measure FBC and perform LFT to monitor for adverse effects