Our objective was to compare the onset and duration of a single dose of pantoprazole or omeprazole on maximally stimulated gastric acid secretion. This double-blind, randomized, placebo-controlled study involved 36 healthy adults and utilized continuous pentagastrin infusion to stimulate acid secretion after administration of pantoprazole, 40 mg, omeprazole, 20 mg, or placebo. Gastric aspirates were collected over 24 hr and analyzed for volume, pH, and hydrogen ion concentration, and gastric acid outputs (GAO) were calculated. Comparison between GAO and intragastric pH was performed. Pantoprazole resulted in significantly greater inhibition of GAO than omeprazole. Mean cumulative 24-hr GAO was 164 +/- 130 mEq for pantoprazole versus 283 +/- 159 mEq for omeprazole (P = 0.031). Pantoprazole patients reached and maintained GAO levels below the 10-mEq/hr threshold at 5.7 hr, whereas omeprazole patients never reached this threshold. We conclude that pantoprazole significantly suppressed gastric acid secretion compared to omeprazole. Comparisons between pH and GAO showed that GAO was a more appropriate measure of gastric acid secretion than intragastric pH.

Pratha, V. S., Hogan, D. L., Lane, J. R., Williams, P. J., Burton, M. S., Lynn, R. B., & Karlstadt, R. G. (2006). Inhibition of pentagastrin-stimulated gastric acid secretion by pantoprazole and omeprazole in healthy adults. Digestive diseases and sciences, 51(1), 123-131.

Intravenous injections of CCK-B agonists, such as pentagastrin, produce symptoms of panic and potent activation of the human hypothalamic-pituitary-adrenal (HPA) axis. It is unclear whether these psychological and endocrine effects are mediated by similar or independent processes. Independence is supported by prior evidence that beta-adrenergic receptor blockade attenuates cardiovascular and symptom but not vasopressin responses to CCK-4. To further explore associations between somatic, emotional and endocrine responses to CCK-B agents, and potential beta-adrenergic mediating mechanisms, symptom and endocrine responses to pentagastrin were examined after propranolol pre-treatment. Cardiovascular, symptom, and endocrine (ACTH, cortisol, epinephrine) responses to pentagastrin were measured in 16 healthy adult subjects randomly assigned to receive propranolol or placebo pre-treatment. Propranolol significantly blocked the normal cardiac acceleration produced by pentagastrin, but did not reduce panic symptom or anxiety effects. It delayed and perhaps enhanced the cortisol response. No relationship between HPA and symptom responses following pentagastrin could be detected, though pre-pentagastrin cortisol was inversely related to post-injection panic symptom intensity. Endocrine, cardiovascular and symptom responses to pentagastrin appear to be separately mediated, as they did not change in concert in response to propranolol pre-treatment, nor were they correlated with one another. The results are consistent with the presence of inhibitory beta-adrenergic mediation of the HPA axis in humans. They support the hypothesis that the HPA response to pentagastrin is not secondary to the psychological stress of its side effects.

Khan, S., Liberzon, I., & Abelson, J. L. (2004). Effects of propranolol on symptom and endocrine responses to pentagastrin. Psychoneuroendocrinology, 29(9), 1163-1171.