PENTAGASTRIN

Absorption

Rapidly absorbed after parenteral administration.

Description

Pentagastrin is a synthetic polypeptide and cholecystokinin-2 (CCK₂) receptor agonist. It binds selectively to CCK₂ receptors in guinea pig brain over CCK₁ receptors in rat pancreas (IC₅₀s = 11 and 1,100 nM, respectively). Pentagastrin increases calcium influx and polyphosphoinositide turnover in rat GH3 pituitary cells (EC₅₀s = 23 and 3.9 nM, respectively). It also increases histidine decarboxylase activity in mucous- and endocrine cell-enriched isolated rabbit fundic mucosal cells (EC₅₀ = 2.9 nM). Pentagastrin induces contraction of isolated pig ileum smooth muscle cells in vitro (EC₅₀ = 30 pM). It increases gastric acid and pepsin secretion in conscious cats in vivo (ED₅₀s = 1.29 and 57.3 nmol/kg² per hour, respectively). Formulations containing pentagastrin have previously been used as a diagnostic aid to evaluate gastric acid secretory function.

Chemical properties

A white or almost white powder.

Originator

Peptavlon,I.C.I. ,UK,1967

The Uses of PENTAGASTRIN

Pentagastrin is a synthetic polypeptide that has effects like gastrin when given parenterally. It stimulates the secretion of gastric acid, pepsin, and intrinsic factor, and has been used as a diagnostic aid as the pentagastrin-stimulated calcitonin test.

The Uses of PENTAGASTRIN

anesthetic (local)

The Uses of PENTAGASTRIN

diagnostic agent for gastric secretion disorders

Background

A synthetic pentapeptide that mimics the actions of endogenous gastrin when given parenterally. It works by stimulating the secretion of gastric acid, pepsin, and intrinsic factor. It has also been used as a diagnostic aid.

Indications

Used as a diagnostic aid for evaluation of gastric acid secretory function

Definition

ChEBI: Pentagastrin is an organic molecular entity.

Manufacturing Process

A solution of 3.55 parts of L-tryptophanyl-L-methionyl-L-aspartyl-Lphenylalanine amide trifluoroacetate in 30 parts of dimethylformamide is cooled to 0°C, and 1.01 parts of triethylamine are added. The mixture is stirred while 1.84 parts of N-tert-butyloxycarbonyl-β-alanine 2,4,5trichlorophenyI ester are added at 0°C. The reaction mixture is kept at 0°C for 48 hours and then at 20°-23°C for 24 hours. The mixture is added to a mixture of 100 parts of ice-water, 0.37 part of concentrated hydrochloric acid (SG 1.18), 1.2 parts of acetic acid and 20 parts of ethyl acetate. The mixture is stirred for 15 minutes at 0°-10°C and is then filtered. The solid residue is washed with water and then with ethyl acetate, and is dried at 40°-50°C under reduced pressure. There is thus obtained N-tert-butyloxycarbonyl-βalanyl-L-tryptophanyl-L-methionyl-L-aspartyl-L-phenylalanine amide, MP 213°C with de composition.

brand name

Peptavlon (Wyeth).

Therapeutic Function

Gastrosecretory hormone

General Description

Pentagastrin (Peptavlon), a physiologicalgastric acid secretagogue, is the synthetic pentapeptide derivative:N-t-butyloxycarbonyl-β-alanyl-L-tryptophyl-L-methionyl-L-aspartyl-L-phenylalanyl amide. It contains theCOOH-terminal tetrapeptide amide (H·Try·Met· Asp·Phe·NH₂), which is considered to be the active center ofthe natural gastrins. Accordingly, pentagastrin appears tohave the physiological and pharmacological properties ofthe gastrins, including stimulation of gastric secretion,pepsin secretion, gastric motility, pancreatic secretion ofwater and bicarbonate, pancreatic enzyme secretion, biliaryflow and bicarbonate output, intrinsic factor secretion, andcontraction of the gallbladder.
Pentagastrin is indicated as a diagnostic agent to evaluategastric acid secretory function, and it is useful in testing foranacidity in patients with suspected pernicious anemia, atrophicgastritis or gastric carcinoma, hypersecretion in suspectedduodenal ulcer or postoperative stomal ulcers, andZollinger-Ellison tumor.

Biochem/physiol Actions

CCKB agonist that stimulates gastric acid secretion; anxiogenic.Pentagastrin is an agonist of the cholecystokinin-2 (CCK2) receptor. It helps to increase the excitability of neurons in the basolateral amygdala through the activation of a non-specific cation channel.

Pharmacokinetics

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.

Metabolism

Primarily hepatic