GI Drugs Flashcards
Antacids example
Gaviscon
Antacids MOA
- Compound containing alginate and 1+ antacid
- Alginate: increase viscosity of stomach contents to reduce reflux
- Antacids: buffer stomach acids
- After reacting with stomach contents, form a floating ‘raft’ which separates gastric contents from GOJ preventing mucosal damage
Antacids indications
- Ulcers
- Non-ulcer dyspepsia
- GORD
Antacids contraindications
- Aluminium / magnesium hydroxide should not be given to patients with hypophosphatemia
- Sodium bicarbonate avoided for patients on low salt diet
Antacids side effects
- constipation / diarrhoea
- flatulence
- stomach cramps
- nausea
Antacids interactions
Divalent cations in compound alginates bind to other drugs and reduce their absorption: ACEi, Abx, bisphosphonates, digoxin, levothyroxine, PPIs.
Doses should be taken at different times - 2 hour gap
Antacids patient info
Action prolonged if durg taken 1-3 hours after food
H2 receptor agonists examples
Ranitidine
H2 receptor agonists indications
- Peptic ulcer disease: treatment and prevention, although PPIs more effective
- GORD / dyspepsia: symptomatic relief
H2 receptor agonists MOA
Histamine from parietal cells binds to H2 receptor
Activates proton pump on parietal cell which secretes H+ into lumen (and draws K+ into cell)
Blockade of H2 = decreased acid
H2 receptor agonists contraindications
Dose reduction in renal impairment
H2 receptor agonists side effects
- Generally well tolerated
- Most common: bowel disturbance, headache, dizziness
PPIs examples
Lansoprazole, Omeprazole Patoprazole
PPIs indications
- Prevention and treatment of peptic ulcer disease including NSAID-associated ulcers
- Symptomatic relief of dyspepsia and GORD
- Eradication of H. Pylori in combination with antibiotics
PPIs MOA
- Irreversibly inhibit H+/K+ ATPase in gastric parietal cells.
- This reduces gastric acid secretion
- More effective than H2 receptor agonists
PPIs administration
Oral
Injectable
PPIs contraindications
-Risk of osteoporosis: can increase fracture risk
PPIs side effects
- GI upset
- Headache
- Reduce host defence against infection - increased risk of C. diff
- Prolonged treatment can cause hypomagnesia - can lead to ventricular arrhythmias