Alternate Name(s):
Flagyl
Classification:
Antibiotic
Original Date:
January 1993
Revised Date:
December 2025
Indications:
- Infections due to susceptible anaerobic organisms
- Definite Necrotizing Enterocolitis
Administration:
- IV intermittent infusion: over 30 - 60 minutes
Dosage:
General Dosing:
| CGA | Loading Dose | Maintenance Dose* |
| 24 to < 34 weeks |
15 mg/kg/dose once |
7.5 mg/kg/dose Q12H |
| 34 to 40 weeks | 15 mg/kg/dose once | 7.5 mg/kg/dose Q8H |
| > 40 weeks | 15 mg/kg/dose once | 10 mg/kg/dose Q8H |
*initiate maintenance dosing 24 hours after the loading dose
Side Effects:
- GI: vomiting, diarrhea
- GU: dark brown urine discolouration
- Hematologic: mild transient leukopenia
- Local: thrombophlebitis
Parameters to Monitor:
- WBC count
Reconstitution and Stability:
- Metronidazole 5 mg/mL (premix bag)
Compatibility:
- Solutions Compatible: D5W, 0.9% NaCl
- Y-site Compatible: acyclovir, dexmedetomidine, dopamine, fluconazole, heparin, hydromorphone, midazolam, milrinone, morphine, piperacillin/tazobactam, SMOF, TPN, vasopressin
Notes:
- Contains 28 mmol Na/g.
References:
- Dannelley JF, Martin EM, Chaaban H, Miler JL. Review of Metronidazole Dosing in Preterm Neonates. Am J Perinatol, 2017 Jul; 34 (9): 833-38.
- Randell RL, Balevic SJ, Greenberg RG, Cohen-Wolkowiez M, Smith MJ, Benjamin DK Jr, Bendel C, Bliss JM, Chaaban H, Chhabra R, Dammann CEL, Downey LC, Hornik CD, Hussain N, Laughon MM, Lavery A, Moya F, Saxonhouse M, Sokol GM, Trembath A, Weitkamp J-H, Hornik CP; Best Pharmaceuticals for Children Act—Pediatric Trials Network Steering Committee. Metronidazole exposure-response and safety in infants. Antimicrob Agents Chemother. 2025 Nov 5;69(11):e0037725.
- Cohen-Wolkowiez M, Sampson M, Bloom BT, Arrieta A, Wynn JL, Martz K, Harper B, Kearns GL, Capparelli EV, Siegel D, Benjamin DK Jr, Smith PB; Best Pharmaceuticals for Children Act–Pediatric Trials Network. Determining population and developmental pharmacokinetics of metronidazole using plasma and dried blood spot samples from premature infants. Pediatr Infect Dis J. 2013 Sep;32(9):956-61.
- Cohen-Wolkowiez M, Ouellet D, Smith PB, James LP, Ross A, Sullivan JE, Walsh MC, Zadell A, Newman N, White NR, Kashuba AD, Benjamin DK Jr. Population pharmacokinetics of metronidazole evaluated using scavenged samples from preterm infants. Antimicrob Agents Chemother. 2012 Apr;56(4):1828-37.
- Taketomo CK, Hodding JH, Kraus DM. Pediatric Dosage Handbook 22nd Edition. Hudson: Lexi-Comp Inc; 2015
- American Society on Health-System Pharmacists (ASHP). Handbook on Injectable Drugs. 19th Edition: Bethesda: ASHP 2017