Metronidazole

C. diff Risk

Low

Oral Bioavailability

NA

Approximate Cost

IV-$3/d PO-$1/d

Spectrum Of Activity

Dosing

Renally cleared, requires dosage adjustment with changes in renal function. Consult with a pharmacist for renal dosing.

Severe impairment: Dose adjustment may be required. Consult with a pharmacist if using in a patient with severe hepatic impairment.

Usual dose, IV: 22.5-40 mg/kg/DAY divided q8h. Max 1500 mg/DAY.

Usual dose, Oral: 30-50 mg/kg/DAY divided into 3 daily doses; Max 2250 mg/DAY

General Information

Common Usage

Suspected or confirmed anaerobic infections including intra-abdominal, biliary, central nervous system, Clostridium difficile, Giardia and pelvic infections.

Also used in Crohns disease, bacterial vaginosis, and hepatic encephalopathy

Drug Monitoring

CBC with differential at baseline and after prolonged or repeated courses of therapy. With prolonged therapy (>6wks) or if symptoms develop assess for peripheral/optic neuropathy

Adverse Effects

GI symptoms common- especially nausea/vomiting and metallic taste

Peripheral/optic neuropathy with extended therapy

Disulfiram-like reaction (severe vomiting)

Rare neurotoxicity including aseptic meningitis and encephalopathy

Major Interactions

Disulfiram reaction wtih alcohol or alcohol-containing medications/products.

May enhance the QT prolongation of drugs which are known to prolong the QT interval

May increase the serum concentation of vitamin K antagonists (warfarin)

Additional Information

Bacterial, protozoal and ameobic DNA is fragmented by reactive nitroso-imidazole radicals

Pharmacology

Antimicrobial class: Nitroimidazole

Average serum half life:

  • Neonates <7 days: (prolonged with lower GA) 24.8-75.3 hours.

  • Neonates ≥7 days: ~22.5 hours

  • Children and adolescents: 6-10 hours.

  • Adults: 8 hours

Route of Elimination:

  • urine (unchanged drug and metabolites: 60-80%; ~20% of total as unchanged drug)

  • feces (6-15%)