Concomitant dosing of famotidine with a triple therapy increases the cure rates of Helicobacter pylori infections in patients with the homozygous extensive metabolizer genotype of CYP2C19.
BACKGROUND
Proton-pump inhibitors, such as lansoprazole, are metabolized in the liver by CYP2C19 and cannot inhibit acid sufficiently in homozygous extensive metabolizers of CYP2C19.


OBJECTIVE
To examine whether famotidine would increase the cure rates of Helicobacter pylori infection by a standard triple therapy.


METHODS
A total of 177 H. pylori-positive patients were randomly assigned to either lansoprazole 30 mg b.d., clarithromycin 200 mg b.d. and amoxicillin 750 mg b.d. for 1 week (LCA group; n = 89) or famotidine 20 mg b.d., lansoprazole 30 mg b.d., clarithromycin 200 mg b.d. and amoxicillin 750 mg b.d. for 1 week (FLCA group; n = 88). Famotidine was administered after lunch and before sleep, and the others were after breakfast and dinner. CYP2C19 genotypes were determined by a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method.


RESULTS
In the LCA group, the eradication rates for homozygous extensive metabolizers, heterozygous extensive metabolizers, and poor metabolizers were 63%, 87%, and 100%, respectively (P = 0.014). Those in the FLCA group were 85%, 85%, and 100%, respectively (N.S.). The cure rate for homozygous extensive metabolizers in the FLCA group was significantly higher than that in the LCA group (P = 0.035).


CONCLUSIONS
Famotidine improves the cure rate of H. pylori infection by a triple therapy in CYP2C19 homozygous extensive metabolizers patients.
Okudaira
K
K
Second Department of Internal Medicine, National Defense Medical College, Tokorozawa, Saitama, Japan. grd1819@gr.ndmc.ac.jp
Furuta
T
T
Shirai
N
N
Sugimoto
M
M
Miura
S
S
D000328:Adult; D000900:Anti-Bacterial Agents; D000897:Anti-Ulcer Agents / Q000627:therapeutic use*; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D065731:Cytochrome P-450 CYP2C19; D004359:Drug Therapy, Combination / Q000627:therapeutic use; D004381:Duodenal Ulcer / Q000188:drug therapy / Q000235:genetics / Q000382:microbiology; D015738:Famotidine / Q000627:therapeutic use*; D005757:Gastritis, Atrophic / Q000188:drug therapy / Q000235:genetics / Q000382:microbiology; D005838:Genotype; D016481:Helicobacter Infections / Q000150:complications / Q000188:drug therapy* / Q000235:genetics; D016480:Helicobacter pylori; D006801:Humans; D008297:Male; D008875:Middle Aged; D006899:Mixed Function Oxygenases / Q000235:genetics*; D013276:Stomach Ulcer / Q000188:drug therapy / Q000235:genetics / Q000382:microbiology; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D000897:Anti-Ulcer Agents; D015738:Famotidine; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19