Anti Ulcer Drugs Flashcards
What is triple therapy?
Coadministration of Antibitics (to eliminate cause), a cytoprotective drug (prevent reocurrnce) and an inhibitor of gastric acid secretion (promote healing) for gastric/duodenal ulcers.
Can also give anatacids.
How do gastric and duodenal ulcers present?
Gastric- pain whilst eating when gastric acid is secreted. Duodenal- during the meal, the pyloric sphincter is closed so no pain. Pain 2-3 hrs later. Duodenal are 4x more common.
What is the function of the mucosal barrier of the GIT and how is it formed? (3) What threatens its integrity?
The mucosal barrier inetgrity is essential for a diease-free state. It functions to lubriacte food and protect the lining from acid and enzymes.
Formed by mucous production from gastric mucosa. HC03 trapped-pH6-7. Mucous and bicarbonate secretion controlled by locally produced prostaglandins.
Its integrity is threatened by acid secretion by parietal cells in oxyntic glands and pepsinogens from chief cells which can erode the mucous layer.
What factors could lead to damage of the mucosal gastro intestinal barrier?
Increased acid secretion, increased pepsin 1, decreased bicarbonate production, decreased thickness of mucous, decreased mucosal blood flow or infections with helicobacter pylori.
Stress, smoking, genetics, diet, alchohol predispose.
Diagnosis via endoscopy
Why is eradication of helicobacter pylori important?
With H.pylori, reoccurence of duodenal is 80% vs 5% without. Aim of treatment is 90% eradication with 7-14 days.
Name 3 regulatory molecules that stimulate gastric acid secretion and describe how
Ach- from enteric neurones, M3 receptor on parietal cells, Ca dependent. Histamine- from ECL cells, H2 on pareital cells, cAMP dependent. Gastrin- from G cells, stumlates histamine release from ECL cells and directly causes prolifertaion of parietl cells via CCK2 receptor.
Name 4 things that inhibits acid secretion
Somatostatin- released in response to low pH, inhibits release of gastrin from G cells and the release of histamine from ECL cells. Secretin and GIP. Prostaglandins E2 and I2 inhibit acid secretion and promote good blood supply via EP3 receptors inhibitijng cAMP synethesis.
What is omeprazole and how does it work?
It is a proton-pump inhibitor- so inhbits stimulated and basal gastric acid secretion by 90% by irreversible inhibtion of H+/K+ ATPase. It is inactive at a neutral pH but collects as a weak base in the bottom of canalicul of parietal cells. This 1) prolongs action to 2-3 days and 2) limits actions elsewhere.
How is it administered and name 3 side effects with long term use
Orally administered with eneteric coated slow release formula. Long term use- risk of penumonia, hip fracture and eneteric infections like C diff.
What are cimetidine and ranitidine?
H2 receptor antagonists - reduce gastric acid secretion by around 60%.
What is the purpose of cytoprotective drugs? name 3
To enhannce mucosal protection mechanisms and/or build a physical barrier over the ulcer.
Sucralfate
Bismuth chelate
Misprostal
What is sucralfate and how does it work? List the major side effect
Sucralfate is a cytoprotective drug. It is a polymer made up of alumium hydroxide and sucrose octa-sulphate. In an ACID environemnt, it forms a strong NEGATIVE charge which binds to positive PROETINS and glycproteins. This results in GEL-LIKE COMPLEXES which coat the ulcer- they PROTECT AGAINST H+ IONS AND PEPSIN DEGRADATION. Also acts to increase prostaglandins, mucous and bicarbonate secretion.
The sucralfate/ AlOH/sucrose octa-sulphate complexes can stay in the GIT and reduce absorption of other drugs.
What is misoprostal, what is its main use and list 3 side effects.
It is a cytoprotective drug- a prostaglandin analogue (so decreases parteial cell acid secretion by EP3 and cAMP decrease. Often co-admisnitered with NSAIDS. Problems- can cuase diarrhoea, abdo cramps and uterine contractions (WATCH OUT for pregnancy)
Name 3 anatacids. Name 2 MOA. Name main use.
Antacids: sodium bicarbonate (fastest), magneisum trisilicate and aluminium hydroxide.
MOA: neutralise stomach acid, which reduces pepsin activity.
Main use: non-ulcer dyspepsia
How do you treat GERD/oesophagitis?
Treat with PPIs, or H2 antagonists. Considor combing with a D2 anatagonsit to promote gastric motility e.g. meteclopramide (an anti-emetic).
