PCAB Regimen for H. pylori Eradication
Use clarithromycin triple therapy (PPI + clarithromycin + amoxicillin) for 14 days ONLY if your local clarithromycin resistance is documented to be less than 15% and local eradication rates exceed 90%; otherwise, choose bismuth quadruple therapy as first-line treatment. 1
Regimen Components
When Clarithromycin Triple Therapy is Appropriate:
- Esomeprazole 40 mg twice daily (preferred high-potency PPI) 1
- Amoxicillin 1000 mg twice daily 1, 2
- Clarithromycin 500 mg twice daily 1
- Duration: 14 days 1
Critical Geographic Restriction:
This regimen is classified as "effective only when susceptibility based" and should NOT be used empirically unless your region has documented clarithromycin resistance <15% and achieves >90% local cure rates. 1 In most regions worldwide, standard triple therapy now provides unacceptably low treatment success. 3
Administration Timing
- Esomeprazole: Take 30 minutes before meals on an empty stomach 1
- Amoxicillin: Take at the start of a meal or 30 minutes after meals 1, 2
- Clarithromycin: Take with other medications twice daily 1
Alternative First-Line Therapy (Preferred in Most Regions)
If clarithromycin resistance is ≥15% or unknown, use bismuth quadruple therapy instead: 1
- Bismuth subsalicylate ~300 mg four times daily 4
- Metronidazole 500 mg three times daily 4
- Tetracycline 500 mg four times daily 4
- PPI (standard dose) twice daily 4
- Duration: 14 days 4
Evidence Quality and Nuances
The American Gastroenterological Association and American College of Gastroenterology guidelines emphasize that clarithromycin triple therapy has become ineffective in most populations due to rising resistance. 1 Research from 2010 confirms that this regimen "now provides unacceptably low treatment success" with few exceptions globally. 3
High-quality evidence from 2013 shows that using high-dose PPI (lansoprazole 60 mg twice daily) with long-acting clarithromycin can achieve 100% eradication in low-resistance areas, regardless of CYP2C19 genotype. 5 However, this requires documented low clarithromycin resistance.
A 2020 meta-analysis found that metronidazole-based triple therapy (PAM) showed comparable or superior efficacy to clarithromycin-based therapy (PAC), particularly in patients over 60 years old and in recent years. 6
Common Pitfalls to Avoid
- Never use clarithromycin triple therapy empirically without knowing local resistance patterns 1
- Do not use 7-day regimens; 14 days is mandatory for optimal eradication 1
- Avoid pantoprazole; prefer esomeprazole 40 mg or rabeprazole 20-40 mg twice daily 4
- After any prior treatment failure, susceptibility testing is mandatory before using this regimen 1
- Complete adherence to the full 14-day course is essential for success 4
Dosing in Special Populations
For patients with severe renal impairment (GFR <30 mL/min), amoxicillin dosing must be adjusted to 500 mg every 12 hours (GFR 10-30 mL/min) or 500 mg every 24 hours (GFR <10 mL/min). 2