Gastric secretion inhibition

Mechanism of Action A peripheral anticholinergic agent that has limited ability to cross the blood-brain barrier and provides a peripheral blockade of muscarinic receptors. Therapeutic Effect Reduces the volume and the total acid content of gastric secretions, inhibits salivation, and reduces gastrointestinal motility. 

Ash and Schlld have made a systematic analysis of the various types of histamine receptors, using several histamine analogs. From studies of gastric secretion. Inhibition of uterine stimulation with carbachol, and stimulation of Ileal smooth muscle, they conclude that there are at least two classes of histamine receptors. 

Figure 6-18. A Effect of infusion of secretin at a constant rate upon rate of secretion of acid by dogs Heidenhain pouches stimulated by infusion of gastrin at various rates. B Dose-response curves for gastrin and gastrin plus secretin derived from data illustrated in A. (From Johnson LR, Grossman Ml. Characteristics of gastric secretion inhibition by secretin. Am I Physiol 217 1401-1404, 1969.)...

Johnson LR, Grossman MI. Characteristics of gastric secretion inhibition by secretin. Am J Physiol 217 1401 -1404, 1969. 

The likeness of effects between the urinary and the intestinal extracts on the gastric secretion inhibition could give the impression that the urinary gastric inhibitor is nothing else but Enterogastrone (probably even partly metabolized) which would have been eliminated by kidneys during the pregnancy. 

The discovery of the antiulcer activity of H2 antihistamine antagonists has revolutionized the treatment of that disease. A benzimidazole. Omeprazole (55), inhibits gastric secretion and subsequent ulcer formation by a quite different mechanism. Studies at the molecular level suggest that this compound inhibits K /H dependent ATPase and consequently shuts down the proton pumping action of this enzyme system. 

Secretin Endocrine cells in mucosa of duodenum Acid in duodenum Inhibits gastric emptying and gastric secretion stimulates secretion of bicarbonate from pancreas stimulates secretion of bicarbonate-rich bile from liver... 

An important gastric secretion is the hydrochloric acid that performs a number of functions in the stomach. This stomach acid is neutralized by pancreatic bicarbonate ion in the duodenum. Excess acid in the chyme stimulates chemoreceptors in the duodenum. This receptor stimulation elicits reflex inhibition of gastric motility. Excess acid also causes the release of secretin and gastric inhibitory peptide from the duodenum. These hormones contribute to inhibition of gastric contractions so that the neutralization process may be completed before additional acid arrives in chyme from the stomach. 

Figure 27. Comparison of the relationship between antihypertensive and sympathomimetic activity and sedation and inhibition of gastric secretion of clonidine and two derivatives (St 600 and St 608). The antihypertensive activity was tested in genetic hypertensive rats. The sympathomimetic activity was measured as blood pressure increase in spinal rats. The sleep effect in chicks was tested according to the method in Reference 50, and the gastric secretion in rats was measured according to the method in Reference 57.

The cycloalkylamine salts of 5-cyano-l-uracilacetic acid and analogues, exemplified by (LI), are claimed to produce marked inhibition of gastric secretion with virtually no anticholinergic activity [378]. This activity is not inherent in the free acetic acid nor in the amine. There is no distinction between optical isomers of the longer chain acids. The pyrimidine portion can be prepared by the treatment of a-cyano-/3-ethoxy-A -(ethoxycarbonyl)acrylamide with alanine or related derivatives [301,302]. 

The main clinical use of H2 receptor antagonists is to inhibit gastric secretion in the treatment of stomach ulcers. These agents all contain features that relate to the histamine structure, in particular the heterocyclic ring. Cimetidine and ranitidine are the most widely used in this class. 

A high rate of ethanol consumption can lead to inhibition of gastric secretion and irritation of the gastric mucosa. Ethanol irritates the entire gastrointestinal tract, which may lead to constipation and diminished absorption of nutrients. Other pathological effects include pancreatitis and peripheral neuropathy. Severe gonadal failure is often found in both men and women, accompanied by low blood levels of sex hormones. 

Mechanism of Action A quaternary anticholinergic that inhibits action of acetylcholine at postganglionic parasympathetic sites in smooth muscle, secretory glands, and CNS. Therapeutic Effect Reduces salivation and excessive secretions of respiratory tract reduces gastric secretions and acidity. 

Selective muscarinic receptor blocker. It inhibits gastric secretion. Thus is effective in peptic ulcer patients and promotes ulcer healing. It does not produce atropinic side effect (due to blockade of and M3 receptors). 

Roxatidine inhibit induced gastric secretion with a potency greater than cimetidine and in the same range as ranitidine. Its acetate salt is more than 95% absorbed after oral administration and rapidly converted to roxatidine by esterases in small intestine and liver. Plasma tVi is 6 hours. Peak plasma levels occur about 8 hours after dosing. Effects of the drug persist for about 12 hours. 

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