What is the dosage and treatment duration for Coamoxiclav (amoxicillin/clavulanic acid)?

Co-Amoxiclav (Amoxicillin/Clavulanic Acid) Dosing and Duration

For adults with respiratory tract infections, use 875 mg/125 mg twice daily or 500 mg/125 mg three times daily for 7-10 days; for more severe infections or when antibiotic resistance is likely, use the high-dose formulation of 2000 mg/125 mg twice daily. 1

Adult Dosing Regimens

Standard Dosing

• Mild to moderate infections: 500 mg/125 mg every 12 hours OR 250 mg/125 mg every 8 hours 1
• Respiratory tract infections and more severe infections: 875 mg/125 mg every 12 hours OR 500 mg/125 mg every 8 hours 1
• Community-acquired pneumonia (hospital-treated, non-severe): 625 mg three times daily orally 2

High-Dose Regimen for Resistant Organisms

• 2000 mg/125 mg twice daily when antibiotic resistance is likely, including: 2

  • Recent antibiotic use (within last 30 days)
  • Contact with healthcare environment
  • Prior antibiotic therapy failure
  • High prevalence of resistant bacteria in the community (>10% penicillin-resistant S. pneumoniae)
  • Age >65 years
  • Comorbidities (diabetes, chronic heart/lung/liver/kidney disease)
  • Immunocompromised status

• This high-dose regimen achieves adequate serum concentrations to eradicate penicillin-resistant Streptococcus pneumoniae with amoxicillin MICs up to 4-8 mg/L 2

Special Infection Types

• Spontaneous bacterial peritonitis: 1 g/0.2 g every 8 hours IV, with similar resolution rates to cefotaxime (87.5% efficacy) 3
• Intra-abdominal infections: 2 g/0.2 g every 8 hours in non-critically ill, immunocompetent patients 2
• Uncomplicated urinary tract infections: 3-7 days duration 2

Pediatric Dosing

Neonates and Infants <12 Weeks

• 30 mg/kg/day divided every 12 hours (based on amoxicillin component) 1
• Use 125 mg/31.25 mg per 5 mL oral suspension formulation 1

Children ≥12 Weeks

Standard dosing:

• Less severe infections: 25 mg/kg/day every 12 hours OR 20 mg/kg/day every 8 hours 2
• More severe infections: 45 mg/kg/day every 12 hours OR 40 mg/kg/day every 8 hours 2

High-dose formulation for resistant infections:

• 90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate in two divided doses for acute bacterial rhinosinusitis and resistant infections 2

Age-based oral suspension dosing:

• 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

Intravenous dosing:

• 30 mg/kg three times daily IV for all pediatric ages 2
• Increase to four times daily in severe infections for patients >3 months 2

Children ≥40 kg

• Dose according to adult recommendations 1
• Do not use 250 mg/125 mg tablets until child weighs at least 40 kg due to different amoxicillin:clavulanic acid ratios 1

Duration of Therapy

• Respiratory tract infections: 7-10 days, may extend up to 14 days depending on clinical response 2
• Acute bacterial rhinosinusitis (adults): 5-7 days 2
• Acute bacterial rhinosinusitis (children): 10-14 days (longer than adults) 2
• Sinusitis: 10-14 days or until symptomatically improved for 7 days 2
• Community-acquired pneumonia: 7-10 days 2
• Uncomplicated urinary tract infections: 3-7 days 2
• Spontaneous bacterial peritonitis: 5-10 days (standard treatment duration) 3

Renal Impairment Dosing

• GFR <30 mL/min: Do not use 875 mg/125 mg dose 1
• GFR 10-30 mL/min: 500 mg/125 mg OR 250 mg/125 mg every 12 hours 1
• GFR <10 mL/min: 500 mg/125 mg OR 250 mg/125 mg every 24 hours 1
• Hemodialysis patients: 500 mg/125 mg OR 250 mg/125 mg every 24 hours, with additional dose during and at end of dialysis 1

Administration Considerations

• Take at the start of a meal to enhance clavulanate absorption and minimize gastrointestinal intolerance 1
• The every 12-hour regimen is associated with significantly less diarrhea compared to every 8-hour dosing 1
• Evaluate clinical response within 48-72 hours of initiating therapy 2
• Switch from IV to oral as soon as clinically appropriate 2

Critical Dosing Warnings

• Do NOT substitute two 250 mg/125 mg tablets for one 500 mg/125 mg tablet—they contain the same amount of clavulanic acid (125 mg) and are not equivalent 1
• Do NOT interchange 250 mg/125 mg tablets with 250 mg/62.5 mg chewable tablets—they contain different amounts of clavulanic acid 1
• Avoid underdosing in areas with high penicillin-resistant S. pneumoniae prevalence (>10%)—always use high-dose formulations 2
• Formulations containing aspartame (200 mg/28.5 mg and 400 mg/57 mg suspensions and chewable tablets) should not be used by phenylketonurics 1

Common Pitfalls

• Gastrointestinal disturbances (particularly diarrhea) are the most common adverse events, occurring in 8.9-15% of patients 4
• Co-amoxiclav has higher rates of gastrointestinal side effects compared to penicillin, with a number needed to harm of 10 5
• In melioidosis, dosing intervals should not exceed 6 hours to maintain adequate T>MIC 6