Pentagastrin

Pentagastrin is a pentapeptide, meaning it consists of five amino acids. Its chemical formula is C37H49N7O9S, and it has a molar mass of 767.90 g/mol . The IUPAC name for pentagastrin is N-(tert-butoxycarbonyl)-β-alanyl-L-tryptophyl-L-methionyl-L-α-aspartyl-L-phenylalaninamide . It is known by the trade name Peptavlon .

Pentagastrin acts by binding to the cholecystokinin-B (CCK-B) receptor, which is widely expressed in the brain and gastrointestinal tract . This binding activates the phospholipase C second messenger system, leading to the secretion of gastric acid, pepsin, and intrinsic factor . These secretions are crucial for the digestive process, aiding in the breakdown of food and absorption of nutrients.

Pentagastrin is used as a diagnostic aid in several medical conditions:

1. Gastric Acid Secretory Function: It helps evaluate the function of gastric acid secretion, which is essential in diagnosing conditions like achlorhydria (absence of hydrochloric acid in gastric secretions), atrophic gastritis, and gastric carcinoma .
2. Zollinger-Ellison Syndrome: This condition is characterized by excessive gastric acid secretion due to gastrin-secreting tumors. Pentagastrin helps in the diagnosis by stimulating gastric acid production .
3. Pentagastrin-Stimulated Calcitonin Test: This test is used to diagnose medullary carcinoma of the thyroid (MTC). In patients with suspected MTC, pentagastrin injection causes a significant rise in calcitonin levels, aiding in the diagnosis .

When administered intravenously, pentagastrin can cause side effects such as panic attacks, flushing, and gastrointestinal discomfort . It is important to monitor patients closely during the administration of pentagastrin, especially those with a history of anxiety or panic disorders.