Acid secretion, gastric reflux

The Hj-receptor blockers include cimetidine, famotidine, and ranitidine. These drugs are used to decrease gastric acid secretion in the treatment of peptic ulcer, gastroesophageal reflux disorder, and hypersecretory conditions, such as Zollinger-ElUson syndrome. The pharmacodynamics and clinical uses of these drugs are discussed in Chapter 40. 

Q8 Examples include famotidine, ranitidine, nizatidine and cimetidine. They prevent food, histamine and acetylcholine-induced gastric-acid secretion. They are used to heal gastric and duodenal ulcers and in gastro-oesophageal reflux disease. 

H2-receptor antagonists are quite effective in some peptic acid disorders (duodenal ulcers, gastric ulcers), whereas their effectiveness in others is less apparent (Zollinger-Ellison syndrome, gastrooesophageal reflux disease) [22]. For such conditions, prolonged and potent reduction of acid secretion caused by H /K -ATPase inhibitors is necessary and results in superiority of omeprazole over H2-receptor antagonists [25, 26]. 

Treatment of hypochloremia can usually be achieved with i.v. 0.9% sodium chloride, which contains more chloride relative to sodium than plasma. In horses with high-volume gastric reflux, administration of i.v. histamine H2 receptor antagonists (e.g. cimetidine at 6.6mg/kg i.v. four times a day) reduces gastric hydrochloric acid secretion and may, therefore, reduce chloride loss. In humans, i.v. hydrochloric acid has been used to treat severe hypochloremia (Kwun et al 1983) but carries substantial risks for the patient (Rothe Schimek 1986). 

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