Rabeprazole (RPZ) concentrations were measured in gastric mucosa from inhibition zones on H. pylori culture medium and calibration curves.
The proton pump inhibitor (PPI) RPZ and H. pylori were used to measure inhibition zone diameters. The methods were prepared according to previously described. RPZ standard dilution solution was used to make drug concentrations of 0.05～100μg/ml. The diameters of inhibition zones were measured with discs method (72 hours, 35℃, in CO2) . The effects of gastric juice on H. pylori were assessed by adding gastric juice obtained during upper gastric endoscopy to the standard dilution solution. Gastric juice was also centrifuged, heat-treated, filtered by dialysis, and dried, and the antibacterial activity evaluated. H. pylori growth was examined using the pre-endoscopy drugs xylocaine spray, xylocaine jelly, gascon drops, and untreated gastric juice.
A linear curve was obtained for drug concentrations of 0.78～100μg/ml, however, marked increases in inhibition zone diameter were seen with gastric juice addition, suggesting the existence of a substance of suppressed H. pylori. The substance seemed to exist for all treatments, with the pre-endoscopic drugs having the greatest inhibitory effect. Untreated gastric juice did not possess the inhibitory effect.
It is hoped that in the future this method can be used directly assay the concentrations of PPIs and other drugs in the gastric mucosa in successful and unsuccesuful H. pylori eradication cases.
