Drugs for GORD Flashcards
What are lifestyle treatment options for peptic disease
- Increase exercise
- Stop smoking
- Reduce alcohol intake
- Do not sleep or lie down after eating
- Using extra pillows when sleeping
- Stop NSAIDs
What are drug therapy options for peptic disease
- Proton pump inhibitors
- H2 receptor antagonists
- Antacids
What are surgical options for peptic disease
- Highly selective vagotomy - denervation of vagus nerve supplying lower oesophagus and stomach, thus reducing acid secretion
- Anti-reflux surgery - wrap fundus of stomach about lower oesophagus to act as a sphincter
What are the defences within the gastric mucosa
- Epithelial integrity
- Small epithelial junctions
- Cell replication and restitution when injury occurs
- Stem cells found in crypts and mobilized when needed
- Mucous membrane barrier
- Vascular supply
- Extensive network of arterioles and venules running within the mucosa and submucosa
What are the aggressive factors which can cause damange to the gastric mucosa
- Acid
- Helicobacter pylori
- Drugs - NSAIDs
Describe the physiology of acid secretion by parietal cells
- Proton pump located on the canalicular membrane which exchanges H out for K in
- Basolateral membrane receptors control rate of action of proton pump
- Acetylcholine (parasympathetics), CCK receptor (gastrin), H2 receptor (histamine)
Describe the mechanism of proton pump inhibitors
- Eg. Omeprazole, lansoprazole
- Block all H+ secretion by destroying proton pumps
- Only bind to active pumps - activated after eating
- Delayed action as not all pumps active all of the time - cannot destroy all pumps immediately
- Max efficacy after 2-3 days - complete acid inhibition
- Restoration of acid secretion requires de novo synthesis after stopping PPI
- Delayed restoration - 2-3 days
- Would have to be given for life to prevent development of Barrett’s oesophagus or cancers - increased ADR risk
Describe the ADRs of proton pump inhibitors
- When proton pump stopped, gastrin levels increase in an attempt to produce acid leading to gastrinomas
- Might change calcium reuptake in small intestine - pH changes to calcium absorption decreases
- Can lead to osteoporosis
- Diarrhoea - increased C. difficile risk
Explain the mechanism of H2 receptor antagonists
- Eg. Cimetidine, ranitidine, nizatidine, famotidine
- Do not block all H+ secretion as other 2 stimulatory pathways still functional
- Have a short half life - 2 doses a day needed
List ADRs of H2 receptor antagonists
- Safe drugs with minimal interactions and ADRs
- Loose stools
- Cimetidine metabolized by CYP450
- Dizziness, confusion, constipation
Describe what antacids and alginates are
- Antacids
- Alkaline buffers - offer temporary relief
- Eg. Aluminium hydroxide (Maalox), gaviscon
- Alkaline buffers - offer temporary relief
- Alginates
- Viscous substance which adheres to gastric/duodenal mucosa to prevent damage
Describe step up regimes in treating GORD/peptic disease
- Step up regimes are usually implemented by primary care
- Lifestyle -> antacids/alginates -> H2 receptor antagonists -> PPI
- Treatment is intensified if previous treatment does not work
Describe step down regimes in treating GORD/peptic disease
- Step down regimes are usually implemented by secondary care
- PPI -> H2 receptor antagonists -> antacids/alginates -> lifestyle
- Treatment is downgraded as patient gets better
Describe how H. pylori can cause peptic ulcer disease
- Gram negative bacteria which can cause gastric and duodenal inflammation/ulceration
- Toxic to epithelial cells and degrade mucous lining by secreting urease
- Ulcers form as stomach acid and pepsin overwhelm the protective mechanism within the stomach
How can you test for H. pylori
Urease breath test, endoscopy, stool antigen test
How can H. pylori be treated
- 2 antibiotics and full acid blockage with PPI
- Clarithromycin + amoxicillin/metronidazole + lansoprazole/omeprazole
- All taken twice a day for 1 week
- Antibiotic choice depends on location - some areas are more resistant to certain antibiotics than other areas
