Proton pump inhibitors are the mainstay of medical management in gastroesophageal reflux disease.
Although they provide relief from most symptoms, reflux may persist.
Dr Jeffrey Peters and colleagues in New York suggested that omeprazole does not reduce the total amount of gastroesophageal reflux but simply alters its pH characteristics.
6 asymptomatic volunteers had combined 24-hour impedance pH monitoring before and after 7 days of omeprazole (20 mg BID).
The research group used multichannel intraluminal impedance to identify reflux episodes, which they classified as acid (pH < 4), weak acid (pH>4 but decrease>1 pH unit) and nonacid (pH>4 and decrease < 1 pH unit) by pH measurements 5 cm above the lower esophageal sphincter (LES).
|Acid reflux episodes were reduced from 63% before to 2.1% after omeprazole|
|Journal of Gastrointestinal Surgery|
The researchers also used a gastric pH sensor located 10 cm below the LES to verify the action of omeprazole.
Using impedance, the research team were able to detect a total of 116 reflux episodes before and 96 episodes after omeprazole treatment.
The researchers found that the median number of reflux episodes, median duration of reflux episodes, and total duration of reflux episodes per subject were similar before and after omeprazole.
In addition, acid reflux episodes were reduced from 63% before to 2.1% after omeprazole, whereas nonacid reflux episodes increased from 15% to 76%.
Weak acid reflux episodes did not change.
The researchers found that the proportion of reflux episodes greater than pH 4 increased from 37% to 98%.
Dr Peters concluded, "In normal subjects, omeprazole treatment does not affect the number of reflux episodes or their duration; rather it converts acid reflux to less acid reflux, thus exposing esophagus to altered gastric juice."
"These observations may explain the persistence of symptoms and emergence of mucosal injury white on proton pump inhibitor therapy."