Metronidazole Pediatric Dose — Antimicrobial Reference
Metronidazole is a nitroimidazole antimicrobial that exerts bactericidal and antiprotozoal activity by disrupting DNA synthesis in susceptible organisms. It is widely used in pediatric practice for anaerobic bacterial infections, intra-abdominal infections, and protozoal conditions such as Giardia and Clostridioides difficile. Both intravenous and oral formulations are available, offering flexibility across clinical settings.
Pediatric Dosing
- 7.5 mg/kg/dose IV or PO every 6 hours
- Adult reference dose: 500 mg/dose every 6 hours
Dosing is administered every 6 hours (four times daily). For a 20 kg child: 20 × 7.5 mg/kg = 150 mg per dose, given four times daily. For a 10 kg child: 10 × 7.5 mg/kg = 75 mg per dose every 6 hours. Doses should not routinely exceed the standard adult dose of 500 mg per dose; consult institutional protocol for maximum single-dose guidance in larger pediatric patients.
Indications and Clinical Context
Metronidazole is indicated for infections caused by anaerobic bacteria and certain protozoa, including intra-abdominal and pelvic infections, C. difficile-associated disease, bacterial vaginosis in adolescents, and parasitic infections such as giardiasis and amebiasis. It is frequently combined with aerobic coverage (e.g., a cephalosporin or aminoglycoside) when polymicrobial infection is suspected, as its spectrum is limited to anaerobes and select protozoa.
In the pediatric emergency and critical care setting, IV metronidazole is a standard component of empiric regimens for complicated appendicitis, peritonitis, and necrotizing soft-tissue infections involving anaerobic organisms. Oral bioavailability is excellent, supporting transition from IV to PO when the patient’s clinical status permits.
Administration and Monitoring
Intravenous doses should be infused over 30–60 minutes; rapid bolus administration is not recommended. Oral formulations (suspension or tablet) may be given with food to reduce gastrointestinal upset. The IV and PO doses are equivalent at 7.5 mg/kg/dose every 6 hours, facilitating straightforward route conversion.
- Adverse effects: Nausea, metallic taste, and gastrointestinal discomfort are most common; peripheral neuropathy and CNS effects (seizures, encephalopathy) are rare but associated with prolonged high-dose use.
- Drug interactions: Inhibits CYP2C9; monitor for enhanced anticoagulant effect if warfarin is co-administered. Disulfiram-like reaction possible with ethanol-containing preparations.
- Contraindications: Hypersensitivity to metronidazole or other nitroimidazoles; use with caution in patients with hepatic impairment, as dose adjustment may be required — consult institutional protocol.
Disclaimer: This article is an educational reference summarizing standard pediatric dosing values. It is not a substitute for clinical judgment. Always verify doses against institutional protocols, the current edition of authoritative references (e.g., Lexicomp, Harriet Lane Handbook, PALS guidelines), the patient’s accurate weight, and any patient-specific factors (renal/hepatic function, allergies, comedications) before administration.