DRUGS TO TREAT GASTRIC ACID SECRETION Helen Turnbull-Ross

What are the 5 functions of the stomach? Dissolve and partially digest the macromolecules in food Storage of food Minimise bacterial ingestion Regulate rate of emptying of stomach contents into the small intestine. Secretion of intrinsic factor

What are the steps for gastric acid secretion by the parietal cells? 1.H + and HCO 3 - are produced from CO 2 and H 2 O. 2. H + is secreted into the lumen by a H + /K + -ATPase pump. 3.HCO 3 - moves out of the cell, across the basolateral membrane via antiport with Cl Cl - diffuses passively into the lumen via a Cl - channel.

Which 3 substances stimulate acid secretion? gastrin acetylcholine histamine Which 3 substances inhibit acid secretion? somatostatin prostaglandins E 2 and I 2 enteric hormones

ECL cell PC H+H+ H+H+ K+K+ K+K+ Cl - H 2 -R Gastrin-R Muscarinic-R Gastrin-RMuscarinic-R Histamine Parietal cell Gastrin ACh Blood vessel Cholinergic nerve + Stimulation of Gastric Acid Secretion

Inhibition of Gastric Acid Secretion ECL cell PC H+H+ H+H+ K+K+ K+K+ Cl - H 2 -RGastrin-RMuscarinic-R Gastrin-R Muscarinic-R Histamine Parietal cell GastrinACh Blood vessel Cholinergic nerve SSR + Somatostatin - - SSR - Somatostatin PGE 2 -R - PGE 2 AA

Name 3 conditions which require drug treatment of acid secretion. Reflux oesophagitis Inflammation of the oesophagus resulting from a failure of the lower oesophageal sphincter. Peptic ulcer Zollinger-Ellison Syndrome Endocrinopathy characterised by gastrin-secreting tumours, which cause multiple, refractory and recurrent peptic ulcers in the distal duodenum and proximal jejunum. The tumour (gastrinoma) is usually in the duodenum (60-65%) or the pancreas (30%). Break in the lining of the stomach

Which drugs classes are used to treat disorders of gastric acid secretion? Antacids and alginates Drugs that protect the mucosa Histamine H 2 -receptor antagonists Proton pump inhibitors

Which of these drugs produces reversible blackening of the tongue and stools? Misoprostol Bismuth chelate Gaviscon Rennie ANSWER = Bismuth Chelate

Which of these drugs will only take effect in an acidic environment? Lansoprazole Ranitidine Alka-Seltzer ANSWER = Lansoprazole Aluminum hydroxide

Side effects of diarrhoea, dizziness, muscle pain, transient rashes and impotence belong to which of these drugs? Esomeprazole Famotidine Misoprostol Magnesium hydroxide (Milk of Magnesia) ANSWER = Famotidine

Which of these drugs should not be given in pregnancy? Omeprazole Misoprostol Gaviscon Bismuth Chelate ANSWER = Misoprostol

What is the first line therapy for H. pylori eradication? Clarithromycin, Amoxicillin, Omeprazole – 14 days Omeprazole, Bismuth chelate, Tetracycline, Metronidozole – 14 days Clarithromycin, Amoxicillin, Omeprazole, Nitroimidazole – 14 days ANSWER = Clarithromycin, Amoxicillin, Omeprazole – 14 days