Metronidazole (Paediatric)

SOURCE: eMC UK SPC, productName 'Metronidazole 200 mg Film-Coated Tablets', §4.2. FORMULATION CAVEAT: this is the ORAL tablet SPC — intravenous and rectal regimens are not covered by this source (§4.2 only notes that surgical prophylaxis is 'followed by postoperative intravenous or rectal administration until the patient is able to take tablets'). VERBATIM anaerobic treatment: 'Adults 800 mg followed by 400 mg 8 hourly.' SURGICAL PROPHYLAXIS (adults): '400 mg 8 hourly during 24 hours immediately preceding operation.' OTHER ADULT INDICATIONS from the §4.2 table (adults and children over 10 years): urogenital trichomoniasis — 2000 mg as a single dose, or 200 mg three times daily, or 400 mg twice daily (7 or 5–7 days; where re-infection is likely the consort should receive a similar course concurrently); bacterial vaginosis — 400 mg twice daily for 5–7 days or 2000 mg as a single dose (1 day); amoebiasis invasive intestinal disease in susceptible subjects — 800 mg three times daily for 5 days; intestinal disease in less susceptible subjects and chronic amoebic hepatitis — 400 mg three times daily for 5–10 days; amoebic liver abscess and other extra-intestinal amoebiasis — 400 mg three times daily for 5 days; symptomless cyst passers — 400–800 mg three times daily for 5–10 days; giardiasis — 2000 mg once daily for 3 days, or 400 mg three times daily for 5 days, or 500 mg twice daily for 7–10 days; acute ulcerative gingivitis — 200 mg three times daily for 3 days; acute dental infections — 200 mg three times daily for 3–7 days; leg ulcers and pressure sores — 400 mg three times daily for 7 days. ELDERLY: well tolerated, but a pharmacokinetic study suggests cautious use of high dosage regimens in this age group. MONITORING: regular clinical and laboratory monitoring (especially leucocyte count) if treatment beyond 10 days is considered necessary (§4.4). Source §4.4 and §4.8 were truncated at the source-fetch limit and §4.5 was not retrieved.

The 7.5 mg/kg figure is the per-DOSE component of the divided regimen for established anaerobic infection. VERBATIM §4.2: children over 8 weeks to 12 years of age — 'The usual daily dose is 20-30mg/kg/day as a single dose or divided into 7.5mg/kg every 8 hours. The daily dose may be increased to 40mg/kg, depending on the severity of the infection. Duration of treatment is usually 7 days.' Children under 8 weeks of age — '15mg/kg as a single dose daily or divided into 7.5mg/kg every 12 hours.' In newborns with a gestational age under 40 weeks, accumulation can occur during the first week of life, so serum metronidazole concentrations should preferably be monitored after a few days of therapy. SURGICAL PROPHYLAXIS: children under 12 years — 20–30 mg/kg as a single dose given 1–2 hours before surgery; newborns with a gestational age under 40 weeks — 10 mg/kg body weight as a single dose before operation. PROTOZOAL INFECTIONS (fixed doses by age band, §4.2 table): trichomoniasis in children — 40 mg/kg orally as a single dose or 15–30 mg/kg/day divided in 2–3 doses; giardiasis children 7–10 years 600–800 mg once daily, 3–7 years 500 mg once daily, or alternatively 15–40 mg/kg/day divided in 2–3 doses; amoebiasis, gingivitis and other indications have separate fixed doses for the 7–10, 3–7 and 1–3 year bands. 'Children and infants weighing less than 10 kg should receive proportionally smaller dosages.' Verify all under-18 dosing against a children's formulary.