J. Pedrazzoli et al., Transfer of clarithromycin to gastric juice is enhanced by omeprazole in Helicobacter pylori-infected individuals, SC J GASTR, 36(12), 2001, pp. 1248-1253
Background: The effects of proton-pump inhibitors and Helicobacter pylori i
nfection on the distribution of drugs employed for the eradication of H. py
lori are poorly understood. The aim of this study was to investigate the ef
fects of a 7-day oral administration of 20 mg omeprazole on the distributio
n of clarithromycin in the gastric juice of individuals with H. pylori infe
ction. Methods: Eighteen H. pylori-infected dyspeptic male volunteers witho
ut endoscopic lesions were enrolled in a study with an open, randomized, tw
o-period crossover design and a 21-day washout period between phases. Plasm
a and gastric juice concentrations of clarithromycin in subjects with and w
ithout omeprazole pretreatment were measured by means of liquid chromatogra
phy coupled to tandem mass spectrometry. Results: The maximum concentration
of clarithromycin (C-max) and the area under the time-concentration curve
from 0 to 2 h (AUC(0-2h)) were significantly higher in gastric juice than i
n plasma. Omeprazole treatment further augmented clarithromycin C-max and A
UC(0-2h) in gastric juice approximately 2-fold (P < 0.05). Conclusions: Sho
rt-term treatment with omeprazole in H. pylori-positive volunteers increase
s the amount of clarithromycin transferred to the gastric juice, confirming
a synergism between these drugs. Our results suggest the presence of an ac
tive transport mechanism for clarithromycin from plasma to the gastric lume
n, which is influenced by omeprazole.