Gastrointestinal Drugs and Medications Q 15
Which of the following drugs will reduce the effectiveness of sucralfate?
A. ranitidine
B. sucralfate
C. metoclopramide
D. meclizine
Correct Answer: A. ranitidine
Ranitidine decreases the effectiveness of sucralfate because it decreases the acid content of gastric 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. Additional indirect effects of ranitidine are decreased pepsin secretion and increased nitrate-reducing bacterial flora.
Option B: Sucralfate is a unique anti-ulcer drug. It is a basic aluminum salt of sucrose octasulfate. It prevents hydrolysis by preventing the formation of the enzyme-substrate complex. It adsorbs to pepsin and decreases its concentration. Increases mucous hydrophobicity, viscosity, sulfation, and the aluminum and carbohydrate content, which leads to improved mucosal protection from acid. It also increases the production of mucus by increasing prostaglandin production. Sucralfate prevents the breakdown of mucus by pepsin A, reducing ulcerogenesis. It increases prostaglandin dependent and independent production of bicarbonate by stomach and duodenum.
Option C: Metoclopramide is a gastric stimulant that does not alter pH. It has been approved by the FDA specifically to treat nausea and vomiting in patients with gastroesophageal reflux disease or diabetic gastroparesis by increasing gastric motility. It is also used to control nausea and vomiting in chemotherapy patients.
Option D: Meclizine is an antihistamine and its GI effect is antiemetic. It is a first-generation antihistamine (non-selective H1 antagonist). It also has central anticholinergic actions. The blocking actions on these receptors give meclizine its antiemetic and antivertigo properties. Meclizine, an FDA- approved drug, is a first-generation antihistamine used for the symptomatic management of motion sickness. These symptoms include dizziness, nausea, and vomiting. It also treats vertigo symptoms caused by vestibular diseases that commonly affect the inner ear, such as Meniere’s disease.