GIT - Upper GI Treatment Flashcards
What are the primary goals of peptic ulcer treatment?
provide pain relief
- antacids and mucosa protectors
eradicate H.pylori infection
- triple therapy = two antibiotics and one acid suppressor
heal the ulcer
- eradicate infection, protect the ulcer until it heals
prevent recurrence
- decrease high acid stimulating foods in susceptible people
- avoid use of potential ulcer causing drugs
- stop smoking
What are the different treatment options and their action?
antacids
- neutralise acid and prevent formation of pepsin
H2- receptor antagonist
- blocks histamine stimulated gastric secretion
muscarinic antagonists
- block acetylcholine-stimulated gastric secretion
proton pump inhibtors
- inhibit H+-K+-ATPase proton pump, suppressing gastric acid production
prostaglandin analogs
- reduce gastric acid, increase mucosa blood flow, augment the secretion of mucus and bicarbonate
mucosal barrier fortifiers
- form a complex gel with the mucus, creating a protective coat
How do antacids work? What are the different types?
antacids are weak bases, they react with HCl to form salt and water
- reduce gastric acidity
systemic antacids
- sodium bicarbonate, sodium citrate
non-systemic antacids
- magnesium hydroxide, magnesium trisilicate, aluminium hydroxide gel, calcium carbonate
What are the advantages and disadvantages of systemic antacids?
advantages
- reacts rapidly with hydrochloric acid to produce carbon dioxide and sodium chloride
disadvantages
- formation of carbon dioxide results in gastric distension
- unreacted alkali is readily absorbed and can cause metabolic alkalosis
- sodium chloride absorption may exacerbate the fluid retention in certain patients
What are the advantages and disadvantages of non-systemic antacids?
advantages
- no gas is formed
= no distension, belching or metabolic alkalosis
disadvantages
- unabsorbed magnesium cause osmotic diarrhoea
- unabsorbed aluminium cause constipation
= both are given together to minimise the impact on bowel function.
How do H2 receptor antagonists work? What are the advantages and disadvantages?
competitively block H2 receptors on parietal cells
advantages
- suppress basal and meal stimulated acid secretion in a linear dose dependent fashion
- most effective in suppressing nocturnal acid secretion
disadvantages
- are less potent than PPIs
What are the side effects of H2 receptor antagonists?
diarrhoea, headache, myalgia, constipation,
fatigue, confusion, hallucination
How do anticholinergic agents work? What are the advantages and disadvantages?
competitively and selectively block M3 receptors on parietal cells
- inhibit acid secretion
- delay gastric emptying
are not commonly used due to their low efficacy and anticholinergic effects
- dry mouth, blurred vision, constipation, urinary retention and drowsiness
How do proton pump inhibitors work? What are the administration requirements and why?
irreversibly inhibits the H+/K+ ATPase pump
- suppresses acid secretion
must be administered orally having fasted or 30 minutes before a meal
PPIs have a short half life but acid suppression occurs for up to 24 hrs (18hrs are needed to synthesise new proton pumps)
are highly bound to plasma proteins; extensively
metabolized in liver and metabolites secreted in urine
What are the side effects of proton pump inhibitors?
headaches
diarrhoea
abdominal pains
may decrease vitamin B12 absorption
increases rate of infection and fracture of bones
- risk osteoporosis
omeprazole inhibits CYP2C19
- affects the metabolism of other drugs
= clopidogrel, warfarin, phenytoin
How do prostaglandin analogs work? What is an example? What are the side effects?
act as prostaglandins and bind to their receptors
- reduce gastric acid secretion
- increases mucosal blood flow
- augment secretion mucus and bicarbonate
misoprostol - PGE1
diarrhoea
abdominal cramps
How doe mucosal barrier fortifiers work? What are examples?
form a complex gel with mucus creating a protective coat
sucralfate
- complex of aluminium hydroxide and sulphated sucrose
= in acidic solutions, it polymerises to a sticky gel which adheres to the ulcer base and protects it
bismuth salicylates and colloidal bismuth subcitrate
- react with proteins in the base of the ulcer and protect it from peptic digestion
- stimulates secretion of mucus, PGE2 and bicarbonate
- antimicrobial effects against H.pylori
- binds to enterotoxins
How should peptic ulcers caused by H.pylori be treated? What is the first, second and third line treatment? What are the first and second line treatment for penicillin allergy?
first line = triple therapy
- lansoprazole + amoxicillin + clarithromycin/metronidazole for seven days
second line = triple therapy
- first line but with the either clarithromycin, metronidiazle or tetracycline for seven days
third line - quadruple therapy
- lansoprazole + bismuth subsalicylate + 2 antibiotics for ten days
penicillin allergy
- lansoprazole, clarithromycin, metronidazole
- lansoprazole, bismuth subsalicylate, metronidazole, tetracycline
What treatment is required when NSAIDs use must continue while treating ulcers?
treat the ulcer with a proton pump inhibitor and on healing continue the PPI or switch to misoprostol for maintenance therapy
treat the ulcer with a proton pump inhibitor and switch non-selective NSAID to a COX-2 selective inhibitor
