ORIGINAL ARTICLE Impact of Acid Suppression on Upper Gastrointestinal pH and Motility Whitney Michalek • John R. Semler • Braden Kuo Received: 27 July 2010 / Accepted: 26 October 2010 / Published online: 18 November 2010 Ó Springer Science+Business Media, LLC 2010 Abstract Background Proton pump inhibitors (PPIs), widely pre- scribed to patients with upper gastrointestinal symptoms, alter intragastric pH, and may affect upper gastrointestinal transit and motility parameters in addition to affecting the ability to determine Wireless Motility Capsule (WMC) gastric emptying time. Aim To assess PPI effect on motility parameters of the upper gastrointestinal tract and to determine if PPIs con- found ability of WMC to measure gastric emptying time. Methods Twenty healthy subjects were treated with esomeprazole 40 mg bid for 1 week. Another 50 healthy subjects underwent evaluation in absence of PPIs. All subjects underwent WMC test after meal ingestion. After a rapid, sustained luminal pH rise C 0.5 pH units, marking potential gastric emptying time of WMC, an abdominal X-ray (KUB) was taken for gastric emptying time confir- mation. Mean pH, pressure and transit time were compared between PPI-treated and untreated groups. Results There was no difference in gastric emptying time, small bowel transit time (SBTT), or pressure profiles between the groups. The pH in all cases rose C 0.5 pH units. Distal small bowel pH was significantly lower in subjects on PPIs. Gastric emptying time was identified in all subjects treated with PPIs. Pressure and slope criteria were developed to confirm the time of emptying. Conclusion PPI therapy does not have a significant impact on upper gastrointestinal transit and motility but it does decrease distal small bowel pH. The medication reduced the magnitude of pH change at gastric emptying time but using additional criteria based on slope and con- traction frequency, WMC was able to measure gastric emptying time in all patients treated with PPIs. Keywords Stomach and duodenum Á Gastric emptying Á Motility Á Acidity (intragastric) Introduction Acid suppression medication is one of the most prescribed classes of therapeutic agents and includes proton pump inhibitors (PPIs), H2-receptor antagonists, and others. PPIs act by targeting the terminal-step in gastric acid produc- tion, resulting in decreased gastric acid secretion. Twice a day, 40 mg omeprazole treatment raises the stomach pH from a median of 1.7 [1] to a median of 6.5 [2]. Some clinically used PPIs include omeprazole, lansoprazole and esomeprazole. A retrospective medical record study was conducted to determine the pattern of use of PPIs and H2-receptor antagonists in clinical practice [3] and found that 2.8% of patients in a managed care population had prescription records consistent with the chronic use of acid suppression therapy. In that population, 47% were taking H2-receptor antagonists and 57% PPIs. The impact of acid suppression on upper gastrointestinal motility function is unclear with mixed reports in the literature. Frequently, patients on PPIs are evaluated for motility disorders for issues such as gastroparesis, nausea and W. Michalek Á B. Kuo (&) Massachusetts General Hospital, 55 Fruit St. GRJ 274, Boston, MA 02114, USA e-mail: bkuo@partners.org W. Michalek e-mail: wmichalek@partners.org J. R. Semler SmartPill Corporation, 847 Main St., Buffalo, NY 14203-1109, USA e-mail: jrsemeler@smartpillcorp.com 123 Dig Dis Sci (2011) 56:1735–1742 DOI 10.1007/s10620-010-1479-8