Medication Guide App

Pentagastrin (Systemic)


VA CLASSIFICATION
Primary: DX900

Commonly used brand name(s): Peptavlon.

Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).



Category:


Diagnostic aid (gastric function)—

Indications

Accepted

Anacidity (diagnosis)—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. {01} {03} {06} {08} {11} {12} {13}

Hypersecretory conditions, gastric (diagnosis)—Pentagastrin is 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. {06} {08} {12} {13}


Pharmacology/Pharmacokinetics

Mechanism of action/Effect:

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. {07} {11}


Other actions/effects:

Pentagastrin increases blood flow in the gastric mucosa, inhibits absorption of water and electrolytes from the ileum, and promotes sodium and chloride diuresis. It causes contraction of the smooth muscle of the lower esophageal sphincter when administered intravenously. Pentagastrin produces an increase in the motor activity of the colon and rectum. {02} {04} {07}

Absorption:

Rapidly absorbed after parenteral administration. {02}

Biotransformation:

Primarily hepatic.

Half-life:

10 minutes or less. {02} {04}

Onset of action:

10 minutes. {01} {02} {04} {12}

Time to peak effect:

20 to 30 minutes. {12}

Duration of action:

60 to 80 minutes. {13}

Elimination:
    Renal. {11}


Precautions to Consider

Pregnancy/Reproduction

Pregnancy—
Studies have not been done in humans.

Studies have not been done in animals.

FDA Pregnancy Category C. {12}

Breast-feeding

It is not known whether pentagastrin is distributed into breast milk. However, problems in humans have not been documented. {12}

Pediatrics

Appropriate studies on the relationship of age to the effects of pentagastrin have not been performed in the pediatric population. Safety and efficacy have not been established. {12}


Geriatrics


No information is available on the relationship of age to the effects of pentagastrin in geriatric patients.

Drug interactions and/or related problems
The following drug interactions and/or related problems have been selected on the basis of their potential clinical significance (possible mechanism in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):

See Diagnostic interference .

Diagnostic interference
The following have been selected on the basis of their potential clinical significance (possible effect in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):

With results of this test

Due to other medications
» Antacids{08}    (administration on the morning of the test may decrease the total effects of pentagastrin and thus is not recommended)


» Anticholinergics, or other medications with anticholinergic activity (see Appendix II ) or{08}
» Histamine H 2-receptor antagonists, such as, cimetidine, famotidine, nizatidine, and ranitidine{08}    (concurrent use may antagonize the effect of pentagastrin; administration of these medications is not recommended during the 24 hours preceding the test)


» Omeprazole{08}    (concurrent use may antagonize the effect of pentagastrin on gastric acid secretion; administration of omeprazole is not recommended during the 96 hours preceding the test {10})

With physiology/laboratory test values
Bicarbonate secretion and
Biliary flow and
Pancreatic enzyme secretion    (may be increased {12})


Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate)— not necessarily inclusive (» = major clinical significance).


Except under special circumstances, this medication should not be used when the following medical problem exists:
» Peptic ulcer, acute, obstructing, penetrating, or bleeding{08}    (condition may be exacerbated)


Risk-benefit should be considered when the following medical problems exist
Biliary disease or
Hepatic function impairment or
Pancreatitis, acute    (stimulation of secretion of pancreatic enzymes and bicarbonate, and increased flow of bile may be undesirable in these conditions {01} {11} {12})


Sensitivity to pentagastrin{08}{12}


Side/Adverse Effects
The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:

Those indicating need for medical attention
Incidence rare
    
Allergic reaction (skin rash or hives)



Those indicating need for medical attention only if they continue or are bothersome
Incidence more frequent
    
Gas
    
gastrointestinal effects (nausea or vomiting; stomach pain; urge to have bowel movement)—usually disappear within 15 minutes after subcutaneous administration

Incidence less frequent or rare {12}
    
Blurred vision
    
cardiovascular effects (fast heartbeat; unusual warmth or flushing of skin)—usually transient
    
chills
    
dizziness, faintness, or lightheadedness
    
drowsiness
    
feeling of heaviness of arms and legs
    
headache
    
increased sweating
    
numbness, tingling, pain, or weakness in hands or feet
    
shortness of breath
    
unusual tiredness





Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Pentagastrin (Diagnostic).

In providing consultation, consider emphasizing the following selected information (» = major clinical significance):

Description of use
Procedure for pentagastrin test: Dose of pentagastrin based on body weight and must be determined by doctor; pentagastrin is injected subcutaneously; 10 or 15 minutes after injection, stomach contents emptied and tested for volume and acidity; procedure may be repeated 4 or 6 times

Before having this test
»   Conditions affecting use, especially:
Sensitivity to pentagastrin
Other medications, especially antacids, anticholinergics, histamine H 2-receptor antagonists, or omeprazole
Other medical problems, especially acute, obstructing, penetrating, or bleeding peptic ulcer

Preparation for this test
Not eating prior to the test beginning the night before or drinking for at least 4 hours before test is administered

» Not taking antacids on morning of test

» Not taking anticholinergics, cimetidine, famotidine, nizatidine, ranitidine, or other medications that inhibit gastric secretion within 24 hours before test; not taking omeprazole within 96 hours before test


Side/adverse effects
Signs of potential side effects, especially allergic reaction


General Dosing Information
Not eating prior to the test beginning the night before the test {08} and abstaining from liquids at least 4 hours before the test are usually recommended since the presence of food or liquid in the stomach may interfere with the interpretation of test results.

After the injection of pentagastrin, four aspirates at 15-minute intervals or six aspirates at 10-minute intervals are collected and examined to determine the stimulated acid output. {02} {11}

Use of doses larger than the recommended dose may cause inhibition of gastric acid secretion. {03} {12}

Pentagastrin has also been administered intramuscularly, intravenously, and as a powder by nasal inhalation. The intramuscular dose used has been the same as the subcutaneous dose. The intravenous infusion dose has ranged from 0.1 to 12 mcg (0.0001 to 0.012 mg) per kg of body weight per hour administered in a 0.9% sodium chloride injection. By nasal inhalation, 1 mg of the powder has been administered every 10 minutes for 1 hour. {02}


Parenteral Dosage Forms

PENTAGASTRIN INJECTION

Usual adult and adolescent dose
Gastric function diagnosis
Subcutaneous, 6 mcg (0.006 mg) per kg of body weight. {01} {12}


Usual pediatric dose
Dosage has not been established. {01}

Usual geriatric dose
See Usual adult and adolescent dose .

Strength(s) usually available
U.S.—


250 mcg (0.25 mg) per mL (Rx) [Peptavlon]

Canada—


250 mcg (0.25 mg) per mL (Rx) [Peptavlon]

Packaging and storage:
Store between 2 and 8 °C (36 to 46 °F), unless otherwise specified by manufacturer. Protect from freezing. {12}



Revised: 07/14/1993



References
  1. Peptavlon product information (Ayerst—US). 1982 PDR.
  1. McEvoy G, editor. AHFS Drug Information. Bethesda, MD: American Society of Hospital Pharmacists, 1992.
  1. Olin B, editor. Facts and Comparisons. St Louis, MO: J.B. Lippincott.
  1. Goodman and Gilman's The pharmacological basis of therapeutics. 8th ed. New York: Pergamon Press, 1990.
  1. Glass GB, editor. Gastrointestinal hormones. New York: Raven Press, 1982: 135.
  1. Peptavlon product information (Ayerst—US), 1991 PDR.
  1. Meneghelli UG, Godoy RB, Oliveira RB, et al. Effect of pentagastrin on the motor activity of the dilated and nondilated sigmoid and rectum in Chagas' disease. Digestion 1983; 27: 152-8.
  1. Jacobs D, editor. Laboratory test handbook. 2nd ed. Baltimore, MD: Williams & Wilkins, 1990: 200-3.
  1. Pentagastrin as a stimulant of maximal gastric acid response in man: a multicentre pilot study. Lancet 1967 Feb 11; 1: 291.
  1. Omeprazole package insert (MSD—US), Rev. 9/89.
  1. Panel comments as of 03/83.
  1. Peptavlon product information (Ayerst—US) Rev 10/90, Rec 6/91.
  1. Peptavlon product information (Ayerst—Canada), 1992 CPS.
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