What is the recommended dose of Amoxicillin (amoxicillin) 400mg/5ml for a 35-pound (approximately 15.9 kilograms) pediatric patient?

Amoxicillin Dosing for a 35-Pound (15.9 kg) Pediatric Patient

For a 35-pound (15.9 kg) child using amoxicillin 400mg/5ml suspension, the recommended dose is 318-398 mg per day (approximately 4-5 ml per day) divided into two doses for mild to moderate infections, or 636-716 mg per day (approximately 8-9 ml per day) divided into two doses for severe infections or lower respiratory tract infections. 1, 2

Weight-Based Dosing Calculation

The standard pediatric dosing for amoxicillin is weight-based, as this child weighs less than 40 kg and requires pediatric calculations rather than adult fixed doses 1, 2:

For mild to moderate infections (ear/nose/throat, skin, uncomplicated UTI):

• 20-25 mg/kg/day divided every 12 hours 1, 2
• For 15.9 kg: 318-398 mg total daily dose
• Practical dosing: 159-199 mg per dose twice daily 1
• Using 400mg/5ml suspension: approximately 2-2.5 ml per dose twice daily

For severe infections or lower respiratory tract infections:

• 40-45 mg/kg/day divided every 12 hours 1, 2
• For 15.9 kg: 636-716 mg total daily dose
• Practical dosing: 318-358 mg per dose twice daily 1
• Using 400mg/5ml suspension: approximately 4-4.5 ml per dose twice daily

Infection-Specific Dosing Guidance

The dose selection depends critically on the infection type and severity 3, 1:

Use lower dose (20-25 mg/kg/day) for:

• Uncomplicated acute otitis media 3, 1
• Mild skin and soft tissue infections 3, 1
• Uncomplicated urinary tract infections 1

Use higher dose (40-45 mg/kg/day) for:

• Community-acquired pneumonia 3, 1
• Acute otitis media with treatment failure 1
• Suspected resistant organisms 3, 1
• Severe infections requiring hospitalization 3, 1

Administration Instructions

Key administration principles to ensure optimal absorption and tolerability:

• Administer at the start of a meal to minimize gastrointestinal intolerance 2
• Shake the suspension vigorously before each dose 2
• The suspension can be placed directly on the child's tongue or mixed with formula, milk, fruit juice, water, or cold drinks, which should be consumed immediately 2
• Store reconstituted suspension in refrigerator (preferable but not required); discard after 14 days 2

Duration of Therapy

Treatment duration varies by infection type 1, 2:

• Most infections require 7-10 days of treatment 1
• Severe infections may require up to 14 days depending on clinical response 1
• Continue treatment for a minimum of 48-72 hours beyond symptom resolution or evidence of bacterial eradication 2
• For Streptococcus pyogenes infections, at least 10 days of treatment is mandatory to prevent acute rheumatic fever 2

Critical Dosing Pitfalls to Avoid

Common errors that must be prevented:

• Never use adult fixed doses for children under 40 kg 1, 4
• Do not round to convenient volumes without ensuring the dose falls within the appropriate mg/kg range 1
• Always calculate doses based on actual body weight in kilograms, not estimated or ideal body weight 1, 4
• The 875 mg tablet formulation should NOT be used in patients with severe renal impairment (GFR <30 mL/min) 2
• Ensure patient weight in kilograms is documented on all prescriptions to prevent dosing errors 1

Special Considerations for This Patient

At 35 pounds (15.9 kg), this child falls into the weight-based dosing category that requires careful calculation 1, 4:

• This weight is below the 40 kg threshold where adult dosing begins 4, 2
• The child requires pediatric weight-based calculations (mg/kg) rather than fixed adult doses 4
• Using the 400mg/5ml suspension allows for precise weight-based dosing without tablet manipulation 1
• Age alone does not determine dosing—weight is the critical factor 4

Renal Function Considerations

For this pediatric patient, renal function assessment is important if there are concerns about kidney disease 2:

• Children with normal renal function do not require dose adjustment 2
• If GFR is 10-30 mL/min: reduce to 250-500 mg every 12 hours depending on severity 2
• If GFR is <10 mL/min: reduce to 250-500 mg every 24 hours 2
• For children on hemodialysis: administer additional dose during and at end of dialysis 2