Pentagastrin (trade name Peptavlon) is a cholecystokinin type B (CCK(B)) receptor agonist, which was indicated as a diagnostic aid for evaluation of gastric acid secretory function. It was effective in testing for an acidity (achlorhydria) in patients with suspected pernicious anemia, atrophic gastritis, or gastric carcinoma. It was effective in determining the reduction in acid output after operations for peptic ulcer, such as vagotomy or gastric resection. Pentagastrin was also indicated as a diagnostic aid in testing for gastric hypersecretion in patients with suspected duodenal ulcer or postoperative stomal ulcer, and for the diagnosis of Zollinger-Ellison tumor. Peptavlon was discontinued, Federal Register determined that product was not discontinued or withdrawn for safety or efficacy reasons. In addition was shown, that Pentagastrin may release adrenocorticotropin (ACTH) and cortisol through direct pharmacological action, perhaps enhanced on first exposure by psychologically mediated novelty effects. Novelty, per se, is not likely the primary mediator of the hypothalamic-pituitary-adrenal (HPA) response. This model may be useful for further study of cognitive-emotional modulators of HPA axis activity.