10. GI Pharmacology Flashcards
What is the role of alginates and antacids?
Buffering stomach acids - antacids
Increase stomach content viscosity an reduce reflux - alginic acid
Give an example of antacid
Gaviscon
What are the ADR of alginates and antacids?
Magnesium salts can cause diarrhoea and aluminium salts can cause constipation
What are the contraindications of alginates and antacids?
Na+ and K+ containing preparations should be used with caution in renal failure
High sucrose in some preparations so hyperglycaemia risk in DM
What are the DDI with alginates and antacids?
Can reduce absorption of many drugs so doses should be separated
Increased urine alkalinity can increase aspirin excretion
How do PPI work?
Irreversible inhibit the H+/K+ ATPase in gastric parietal cells
Significant reduction in acid secretion
Name two PPI
Lansoprazole
Omeprazole
What a re the ADR of PPI?
GI disturbance - abdominal pain, constipation, diarrhoea
Headache, dizziness
Drowsiness/confusion
What are the contraindications of PPI?
Mask symptoms of gastro-oesophageal cancer
Osteoporosis - fracture risk
What are the DDI of PPI?
Omeprazole CYP inhibitor - reduced clopidogrel action
PPIs can increase effects off warfarin and phenytoin
Name a histamine (H2) receptor antagonist
Ranitidine
How do H2 receptor antagonists work?
Inhibition of H2 receptors - local histamine release continues to proton pump activation
What are the ADR of H2 receptor antagonists?
Generally well tolerated
Diarrhoea, headache
What are the contraindications of H2 receptor antagonists?
Mask systems off gastro-oesophageal cancer, renal impairment
What treatment is given in H. Pylori?
Lansoprazole + clarithromycin + amoxicillin
Or
Lansoprazole + clarithromycin + metronidazole (where allergic to amoxicillin)
