💊 Metronidazole

Metronidazole is a nitroimidazole antibiotic and antiprotozoal agent, effective against anaerobic bacteria and certain parasites.

It is a prodrug that is reduced by anaerobic organisms to active metabolites. These metabolites disrupt DNA synthesis and cause DNA strand breakage, leading to bacterial cell death.

Metronidazole is widely used for anaerobic bacterial infections, including intra-abdominal infections, pelvic inflammatory disease, and C. difficile infection (first-line for mild-moderate). It is also effective against protozoal infections such as giardiasis, amoebiasis, and trichomoniasis.

Hypersensitivity to metronidazole or other nitroimidazole derivatives is an absolute contraindication. It should be used with caution in patients with severe hepatic impairment due to altered metabolism, and in those with active CNS disease.

Common adverse effects include nausea, vomiting, metallic taste, and abdominal cramps. A disulfiram-like reaction (flushing, palpitations, headache, nausea) can occur with alcohol consumption. Peripheral neuropathy and seizures are rare but serious neurological adverse effects, especially with prolonged use.

For short courses, routine monitoring is generally not required. For prolonged or high-dose therapy, particularly in patients with hepatic impairment, liver function tests and full blood count may be considered. Monitor for neurological symptoms like numbness or tingling.

Crucially, counsel patients to avoid alcohol during treatment and for at least 48 hours after the last dose. Check for drug interactions, particularly with warfarin (potentiates anticoagulant effect). Advise patients to report any numbness or tingling in their extremities.

Metronidazole is a cornerstone for anaerobic infections and C. difficile. The disulfiram-like reaction with alcohol is a high-yield fact. It is also used topically for rosacea. Be aware of its potential for neurological side effects with prolonged use.

SBAs frequently test the 'no alcohol' advice with metronidazole due to the disulfiram-like reaction. Questions may also focus on its use in C. difficile infection or its efficacy against anaerobic bacteria and specific protozoa.