Cure of refractory duodenal ulcer and infection caused by Helicobacter pylori by high doses of omeprazole and amoxicillin in a homozygous CYP2C19 extensive metabolizer patient

A 53‐year old female patient with duodenal ulcer and Helicobacter pylori infection was treated three times with a proton pump inhibitor–based triple therapy, such as lansoprazole‐clarithromycin‐amoxicillin (INN, amoxicilline) and lansoprazole‐minocycline‐cefaclor. However, the H pylori infection was not cured. A culture test revealed that her infection was a clarithromycin‐resistant but amoxicillin‐sensitive strain of H pylori . Moreover, a polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) analysis revealed that she was a homozygous extensive metabolizer of cytochrome P450 (CYP) 2C19 (wt/wt). The usual dose of the proton pump inhibitor was therefore assumed to be insufficient for her and then she was treated with a high dose of omeprazole (120 mg/day) and amoxicillin (2250 mg/day) for 2 weeks. The H pylori infection and the ulcer lesion were then cured. One of the factors associated with success or failure of cure of H pylori infection by the proton pump inhibitor–based triple therapy appeared to be CYP2C19 genotype status. Dual treatment with a sufficient dose of a proton pump inhibitor plus amoxicillin could cure H pylori infection even after the failure to cure H pylori infection by a usual proton pump inhibitor–based triple therapy in patients with the wt/wt homozygous extensive metabolizer genotype of CYP2C19. Clinical Pharmacology & Therapeutics (2000) 67 , 684–689; doi: 10.1067/mcp.2000.106826