What is the proper dosage and treatment protocol for Amoxicillin?

Amoxicillin Dosage and Treatment Protocol

The proper dosage of amoxicillin varies by indication, patient age, weight, and infection severity, with adult standard doses ranging from 250-875 mg every 8-12 hours and pediatric doses typically 20-45 mg/kg/day divided every 8-12 hours. 1

Adult Dosing

Standard Dosing by Infection Type

• Ear/Nose/Throat, Skin/Skin Structure, Genitourinary Tract:

  • Mild/Moderate: 500 mg every 12 hours or 250 mg every 8 hours
  • Severe: 875 mg every 12 hours or 500 mg every 8 hours 1

• Lower Respiratory Tract:

  • 875 mg every 12 hours or 500 mg every 8 hours (regardless of severity) 1

• Bronchiectasis Exacerbations:

  • For Streptococcus pneumoniae: 500 mg three times daily for 14 days
  • Alternative higher doses: 1 g three times daily or 3 g twice daily 2

• Community-Acquired Pneumonia:

  • 3 g/day when treating suspected pneumococcal infections 2

• H. pylori Infection:

  • Triple therapy: 1 g amoxicillin twice daily with clarithromycin and lansoprazole for 14 days
  • Dual therapy: 1 g amoxicillin three times daily with lansoprazole for 14 days 1

Special Considerations

• Renal Impairment:
  • GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours
  • GFR <10 mL/min: 500 mg or 250 mg every 24 hours
  • Hemodialysis: 500 mg or 250 mg every 24 hours plus additional dose during and after dialysis 1
  • Avoid 875 mg dose in patients with GFR <30 mL/min 1

Pediatric Dosing

Standard Dosing by Age and Weight

• Children ≥3 months and <40 kg:

  • Mild/Moderate infections: 25 mg/kg/day divided every 12 hours or 20 mg/kg/day divided every 8 hours
  • Severe infections: 45 mg/kg/day divided every 12 hours or 40 mg/kg/day divided every 8 hours 1

• Children <12 weeks (3 months):

  • Maximum 30 mg/kg/day divided every 12 hours due to immature renal function 1

• Community-Acquired Pneumonia:

  • Children <3 years: 80-100 mg/kg/day in three daily doses 2

• Acute Otitis Media:

  • 80-90 mg/kg/day in 2 divided doses 2

Duration of Treatment

• General Principle: Continue treatment for 48-72 hours beyond symptom resolution 1
• Streptococcal Infections: Minimum 10 days to prevent acute rheumatic fever 1
• Bronchiectasis Exacerbations: 14 days 2
• H. pylori Infection: 14 days 1
• Erysipeloid: 7-10 days 2

Administration Guidelines

• Take at the start of a meal to minimize gastrointestinal intolerance 1
• For oral suspension:
  • Shake well before using
  • Refrigeration preferred but not required
  • Discard unused portion after 14 days 1

Common Pitfalls and Considerations

1. Bacterial Resistance:

   • Consider local resistance patterns when selecting dosage
   • Higher doses (e.g., 3 g/day) may be needed for suspected pneumococcal infections with decreased penicillin susceptibility 2

2. Combination Therapy:

   • For beta-lactamase producing organisms, use amoxicillin-clavulanate instead of amoxicillin alone 2
   • Consider amoxicillin-clavulanate for children with insufficient H. influenzae vaccination or concurrent purulent otitis media 2

3. Treatment Failure:

   • Assess response after 48-72 hours
   • If no improvement, consider alternative antibiotics or reevaluation 2

4. Allergic Reactions:

   • Cross-reactivity with cephalosporins is lower than historically reported
   • Second and third-generation cephalosporins have negligible cross-reactivity with penicillin 2

5. Urinary Tract Infections:

   • Short-course therapy (3 days) may be insufficient for childhood UTIs 3
   • Standard 7-10 day course generally recommended for uncomplicated UTIs

By following these evidence-based dosing guidelines and considering patient-specific factors, clinicians can optimize amoxicillin therapy for effective treatment while minimizing adverse effects and antimicrobial resistance.