What is the dosing regimen for Co-amoxiclav (amoxicillin/clavulanic acid)?

Co-amoxiclav Dosing Regimens

Co-amoxiclav dosing depends critically on patient age, infection severity, and local resistance patterns, with pediatric patients requiring weight-based dosing and adults requiring higher doses for resistant organisms or severe infections. 1

Pediatric Dosing

Neonates and Infants <12 Weeks

• 30 mg/kg/day divided every 12 hours (based on amoxicillin component) due to incompletely developed renal function 1
• Use 125 mg/31.25 mg per 5 mL oral suspension (experience with 200 mg/28.5 mg formulation is limited in this age group) 1

Children ≥12 Weeks to <40 kg

Standard dosing by age for oral suspension: 2, 3

• Birth to 1 year: 0.266 ml/kg of 125/31 suspension three times daily, or 2.5 ml three times daily 2
• 1-6 years: 5 ml of 125/31 suspension three times daily 2
• 7-12 years: 5 ml of 250/62 suspension three times daily 2
• 12-18 years: 1 tablet (250/125) three times daily 2

High-dose regimen for severe infections or resistant organisms:

• 90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate in 2 divided doses for otitis media, sinusitis, lower respiratory tract infections, and more severe infections 3, 4, 1
• This provides a 14:1 ratio of amoxicillin to clavulanate, which causes less diarrhea than other formulations while maintaining efficacy 3
• The high-dose regimen achieves middle ear fluid concentrations adequate to overcome penicillin-resistant S. pneumoniae 3

Alternative moderate-dose regimen: 1

• 45 mg/kg/day every 12 hours or 40 mg/kg/day every 8 hours for more severe infections 1
• 25 mg/kg/day every 12 hours or 20 mg/kg/day every 8 hours for less severe infections 1

Intravenous dosing:

• 30 mg/kg three times daily IV for all pediatric ages 2, 3
• Dose frequency can be increased to 4 times daily in severe infections for patients >3 months 2

Children ≥40 kg

• Dose according to adult recommendations 1

Adult Dosing

Standard Oral Regimens

For mild-to-moderate infections: 5

• 500 mg/125 mg three times daily provides adequate coverage 5
• 875 mg/125 mg twice daily is specifically recommended for respiratory infections including acute bacterial rhinosinusitis, community-acquired pneumonia, and acute exacerbations of chronic bronchitis 5

For hospital-treated non-severe pneumonia: 2

• 625 mg three times daily orally 2

For severe infections or high resistance risk:

• 2000 mg/125 mg twice daily achieves adequate serum concentrations to eradicate penicillin-resistant S. pneumoniae with amoxicillin MICs up to 4-8 mg/L 4, 6
• This high-dose regimen is indicated when antibiotic resistance is likely, including recent antibiotic use, contact with healthcare environment, prior antibiotic therapy failure, or high prevalence of resistant bacteria in the community 4

Intravenous Dosing

For hospital-treated severe pneumonia and serious infections: 2, 5

• 1.2 g three times daily IV 2, 5
• Alternative: cefuroxime 1.5 g three times daily IV or cefotaxime 1 g three times daily IV 2

Duration of Therapy

• Acute otitis media: 10 days 1
• Acute bacterial rhinosinusitis (adults): 5-7 days 4, 5
• Acute bacterial rhinosinusitis (children): 10-14 days 4
• Community-acquired pneumonia: 7-10 days, may need up to 14 days depending on clinical response 2, 4, 5
• Bacterial pneumonia (children): 10 days 3
• Intra-abdominal infections: 4-7 days with adequate source control 5
• Uncomplicated urinary tract infections: 3-7 days 4

Critical Dosing Considerations

Risk factors requiring high-dose therapy in children: 3

• Age <2 years
• Daycare attendance
• Recent antibiotic use (within 30 days)
• Moderate to severe illness
• Incomplete vaccination against Haemophilus influenzae type b (<3 injections)
• Concurrent purulent otitis media

Risk factors requiring high-dose therapy in adults: 4

• Recent antibiotic use
• Contact with healthcare environment
• Previous antibiotic therapy failure
• High prevalence of resistant bacteria in the community (>10% penicillin-resistant S. pneumoniae)
• Comorbidities (diabetes, chronic heart/lung/liver/kidney disease)
• Immunocompromised status
• Age >65 years

Common Pitfalls to Avoid

• Never substitute two 250 mg tablets for one 500 mg tablet, as this results in excessive clavulanate dosing 5
• The 250 mg/125 mg tablet and 250 mg/62.5 mg chewable tablet are NOT interchangeable due to different clavulanic acid content 1
• Verify suspension concentration (125/31 vs 250/62) before calculating volume to avoid dosing errors 3
• Using standard doses when high-dose therapy is indicated leads to treatment failure with resistant organisms 3
• Switch from IV to oral as soon as clinically appropriate; for parenteral cephalosporins, switch to co-amoxiclav 625 mg three times daily rather than oral cephalosporins 2
• Doses may be doubled in severe infections for both oral and IV formulations 2
• Evaluate clinical response within 48-72 hours of initiating therapy 4