Mechanism of action of Pentagastrin

Pentagastrin's IUPAC chemical name is "N-((1,1-dimethylethoxy)carbonyl)-beta-alanyl-L-tryptophyl-L-methionyl-L-alpha-aspartyl-L-phenylalaninamide".Pentagastrin is a gastrin-like molecule used as a diagnostic aid for the evaluation of gastric acid secretory function, gastric hypersecretion, and Zollinger-Ellison tumors.

Pharmacodynamics

Pentagastrin is indicated as a diagnostic aid for evaluation of gastric acid secretory function. It is effective in testing for anacidity (achlorhydria) in patients with suspected pernicious anemia, atrophic gastritis, or gastric carcinoma. It is also effective in determining the reduction in acid output after operations for peptic ulcer, such as vagotomy or gastric resection.

Mechanism of action

The exact mechanism by which pentagastrin stimulates gastric acid, pepsin, and intrinsic factor secretion is unknown; however, since pentagastrin is an analogue of natural gastrin, it is believed that it excites the oxyntic cells of the stomach to secrete to their maximum capacity. Pentagastrin stimulates pancreatic secretion, especially when administered in large intramuscular doses. Pentagastrin also increases gastrointestinal motility by a direct effect on the intestinal smooth muscle. However, it delays gastric emptying time probably by stimulation of terminal antral contractions, which enhance retropulsion.

Pentagastrin stimulation test

Pentagastrin is also used as a stimulation test to elevate of several hormones, such as serotonin. It provokes flushing and is useful in evaluating patients who describe flushing, but have normal or only marginally elevated biochemical markers for carcinoid syndrome.

It has been used to stimulate ectopic gastric mucosa for the detection of Meckels diverticulum by nuclear medicine.