Validation of pH Dataloggers for Pharmacologic Studies

Twenty-four-hour gastric aspiration studies have been superseded by dataloggers that continuously record intragastric pH. We have studied both techniques in a practical pharmacologic study, comparing early evening versus nighttime dosing with ranitidine and nizatidine against placebo. Whereas there was a highly significant point correlation between aspiration and datalogger pH, the slope was significantly less than 1. The correlation was poorer during the day (r = 0.51) than at night (r = 0.83). Irrespective of the techniques used, however, conclusions reached on drug efficacy were similar, but direct comparison of data from the two techniques is not possible.