Augmentin Dosing for an 18 kg Pediatric Patient
For a pediatric patient weighing 18 kg, the recommended dose of Augmentin (amoxicillin/clavulanate) is 45 mg/kg/day of the amoxicillin component in two divided doses for mild to moderate infections, or 90 mg/kg/day in two divided doses for severe infections.
Dosing Calculation
Standard Dose (Mild to Moderate Infections):
- Amoxicillin component: 45 mg/kg/day
- For 18 kg child: 45 mg/kg × 18 kg = 810 mg/day
- Divided into two doses: 405 mg per dose, given twice daily
High Dose (Severe Infections):
- Amoxicillin component: 90 mg/kg/day
- For 18 kg child: 90 mg/kg × 18 kg = 1,620 mg/day
- Divided into two doses: 810 mg per dose, given twice daily
When to Use Standard vs. High Dose
Use the high-dose formulation (90 mg/kg/day) when:
- Treating severe infections
- Managing lower respiratory tract infections
- Dealing with suspected drug-resistant pathogens
- Child has recently received antibiotics in the past 30 days
- Child attends daycare (increased risk of resistant organisms)
- Child is under 2 years of age 1
Use the standard dose (45 mg/kg/day) when:
- Treating mild to moderate infections of the ear, nose, throat, skin, or genitourinary tract
- No risk factors for resistant pathogens are present 2
Administration Guidelines
- Administer at the start of a meal to minimize gastrointestinal intolerance 2
- Continue treatment for a minimum of 48-72 hours after the patient becomes asymptomatic 2
- For infections caused by Streptococcus pyogenes, treatment should continue for at least 10 days 2
- Shake oral suspension well before using 2
Formulation Selection
The FDA-approved formulation of Augmentin is available in several strengths:
- Oral suspension: 125 mg/5 mL or 250 mg/5 mL of amoxicillin component
- For the 18 kg child on standard dose (405 mg per dose), this would require approximately 8-8.5 mL of the 250 mg/5 mL suspension per dose
- For high dose (810 mg per dose), consider using the high-dose pediatric formulation (Augmentin ES-600) which contains 600 mg/5 mL of amoxicillin 3, 4
Important Considerations
- The high-dose formulation (Augmentin ES-600) provides a 14:1 ratio of amoxicillin to clavulanate, compared to the 7:1 ratio in standard formulations, allowing for higher amoxicillin doses without increasing clavulanate (which is associated with GI side effects) 4
- Refrigeration of the reconstituted suspension is preferable but not required 2
- Any unused portion must be discarded after 14 days 2
- Monitor for common side effects, primarily mild gastrointestinal disturbances such as diarrhea 5