Which of the following best describes the method of action of medications, such as ranitidine (Zantac), which are used in the treatment of peptic ulcer disease?
A. Neutralize acid.
B. Reduce acid secretions.
C. Stimulate gastrin release.
D. Protect the mucosal barrier.
Correct Answer: B. Reduce acid secretions.
Ranitidine is a histamine-2 receptor antagonist that reduces acid secretion by inhibiting gastrin secretion. Ranitidine is a competitive inhibitor of histamine H2-receptors. The reversible inhibition of H2-receptors in gastric parietal cells results in a reduction in both gastric acid volume and concentration. Ranitidine’s acid-lowering effect is more pronounced for basal and nocturnal acid secretion than it is for food-stimulated acid secretion.
Option A: The antacids reduce the acid reaching the duodenum by neutralizing the acid present in the stomach. The salts’ mechanism of neutralization of acid varies, and each salt has a different mechanism with the ultimate goal of acid neutralization. The formulation of aluminum hydrochloride and water results in the neutralization of the acid in the stomach. It is also known to inhibit pepsin activity.
Option C: Gastrin release is stimulated by the stretching of the stomach walls during a meal, the presence of certain foods (particularly proteins) within the stomach cavity, and an increase in the pH levels of the stomach (i.e. the stomach becoming less acidic).
Option D: Sucralfate, a polymer of sucrose with aluminum hydroxide, forms a protective coating on the mucosal lining, particularly in ulcerated areas. In the presence of acid, it becomes a gel that adheres to epithelial cells and ulcer craters. Sucralfate is only minimally absorbed and can cause constipation.
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