Metronidazole

Provider Level

RN/Paramedic

Class

Antibiotic, antiprotozoal

Mechanism of Action

Diffuses into the organism, inhibits protein synthesis by interacting with DNA and causing a loss of helical DNA structure and strand breakage. Therefore, it causes cell death in susceptible organisms (primarily anaerobes and protozoa).

Indications

Treatment of severe anaerobic infections, intra-abdominal infections, pelvic infections, and certain protozoal infections (e.g., amebiasis, trichomoniasis). Often utilized in critical care interfacility transport.

Contraindications

Hypersensitivity to metronidazole or other nitroimidazole derivatives; first trimester of pregnancy in patients with trichomoniasis; concurrent use of disulfiram within the last 2 weeks; concurrent use of alcohol.

Routes

PO, IV

Onset / Duration

Onset: Rapid (IV), 1-2 hours (PO). Duration: 8-12 hours. Half-life is approximately 8 hours.

Adverse Effects

Nausea, vomiting, diarrhea, metallic taste, headache, dizziness, peripheral neuropathy, seizures, encephalopathy, dark urine, local thrombophlebitis at IV site.

Precautions & Interactions

Use with caution in patients with severe hepatic impairment, severe renal impairment, or a history of central nervous system diseases or blood dyscrasias. Potentiates the effects of warfarin.

Special Considerations

A disulfiram-like reaction (severe nausea, vomiting, flushing, tachycardia) can occur if alcohol is consumed during therapy and for at least 3 days afterward. Discontinue immediately if neurologic symptoms (e.g., seizures, neuropathy) develop. Authorized for RN/Paramedic use during interfacility transport.