Disclaimer to the On-line Edition
This Manual has been designed for use in the NICU at London Health Sciences Centre (LHSC), London, Ontario, Canada, and represents clinical practice at this institution. The information contained within the Manual may not be applicable to other centres. If users of this Manual are not familiar with a drug, it is recommended that the official monograph be consulted before it is prescribed and administered. Any user of this information is advised that the contributors, Editor and LHSC are not responsible for any errors or omissions, and / or any consequences arising from the use of the information in this Manual.



  • the treatment of documented or suspected infections caused by susceptible anaerobic bacteria
  • used as perioperative prophylaxis in infants undergoing contaminated or potentially contaminated GI surgery (eg. perforation due to NEC)


  • metronidazole is active against most obligately anaerobic bacteria (including several Bacteroides species, Clostridium, Peptococcus and Peptostreptococcus) and many protozoa (including Trichomonas vaginalis and Giardia lamblia)
  • the exact mechanism of action has not been determined
  • metronidazole is well absorbed when given orally
  • in adults, up to 60 % of an IV or oral dose is metabolized in the liver
  • half-life in neonates is reported to be 25-75 hours

Side Effects

  • diarrhea, vomiting, constipation
  • peripheral neuropathy, seizures
  • thrombophlebitis, leukopenia


  • may cause the urine to be dark or reddish-brown in colour; this is the result of water-soluble pigments which come from metabolism of the drug
  • use with caution in infants with CNS disease, liver failure or renal failure


1200 - 2000 g < 7 days old7.5 mg/kg IV (or po) q24h
1200 - 2000 g > 7 days old7.5 mg/kg IV (or po) q12h
> 2000 g and < 7 days old7.5 mg/kg IV (or po) q12h
> 2000 g and > 7 days old15 mg/kg IV (or po) q12h
  • it is unclear at the present what the dosage recommendation should be in infants less than 1200 g. A dose of 7.5 mg/kg q48h has been suggested for infants less than 1200 g and less than 28 days old; however, the Clinician will have to weigh the clinical situation and the properties of the drug to make a dosage decision
  • give IV by slow infusion
  • give oral suspension with feeds to minimize GI upset


  • 5 mg/mL syringe, prepared by Pharmacy
  • 500 mg/100mL IV solution for after hours use
  • 20 mg/mL oral suspension, prepared by Pharmacy


  1. McEvoy G K (ed): AHFS Drug Information, American Society of Hospital Pharmacists, 1991.
  2. Nelson JD: Pocketbook of Pediatric Antimicrobial Therapy, 7th Edition, 1987, Williams and Wilkins, Baltimore.
  3. Krogh CME et al (ed): Compendium of Pharmaceuticals and Specialties, Canadian Pharmaceutical Association, 1992.
  4. Gomella TL (Ed): Neonatology - Management, Procedures, On-Call Problems, Diseases, Drugs, 1992, Appleton and Lange, Norwalk, Connecticut.
  5. Taketomo CK, Hodding JH and Kraus DM: Pediatric Dosage Handbook, Lexi-Comp Inc., Cleveland, 1992.
  6. Prober CG, Stevenson DK and Benitz WE: The use of antibiotics in neonates weighing less than 1200 grams, Pediatr Infect Dis J 1990; 9: 111-121.

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