GIT Flashcards
What are the Cells in stomach
Parietal cell
Proton pump: swap H+ for K+
Foveolar (Mucous) cells
Smooth muscle cell
Antacids
- Mechanism of action: weak bases (HCO3- and a metal to form powder) combine with HCl results in H2O and CO2 therefore neutralising acid
- Metal compounds of antacids: Al, Mg, Na, Cl, K
- Pepsin inactive above pH of 4
- Examples of anatacids: Al hydroxide, Mg carbonate, Mg trisilicate, Na bicarbonate
Common adverse effects of antacids
- Aluminium-based drugs bind with other drugs when given concurrently necessitating a higher dose to achieve therapeutic effects
- Aluminium-based drugs also render certain drugs inactive
- Magnesium-based drugs cause diarrhoea
- Calcium carbonate in antacids can cause calcification of soft tissue and increase the risk for kidney stones.
- Sodium bicarbonate produces carbon dioxide, leading to belching.
- All antacids can lead to acid rebound.
- Indigestion > diarrhoea > later constipation (patients can alternate antacids and laxatives which can cause problems)
Proton pump inhibitors
- HCl formation depends on the supply of H+ protons
- Family name of prazole inhibits proton pump
- Omeprazole, esomeprazole, rabeprazole
- Used for GORD, reflux, oesophagitis, peptic ulcer
- Peptic ulcer treatment if caused
Prokineatic agetns examples
cisapride and prucalopride
Side effects of prokinetic agents
Cisapride: interacts with grapefruit causing increased drug plasma levels, take 30 mins before meal
Prucalopride: chronic constipation
Antiflatulents
Treat pain associated with flatulence
Examples: simethicone, dimethicone (charcoal is active form rarely used)
Clinical considerations: may increase risk of reflux
Histamine H2- receptor antagonists
Supress H2- receptors which produce acid
Examples: cimetidine, ranitidine, nizatidine
Clinical considerations: avoid alcohol, smoking, aspirin, caffeine and spicy foods
Side effects of H2- receptor inhibitiors
Headache, dizziness MSK pain Rash GIT upset, altered liver function, inhibit gastric acid secretion Psychic disturbance
M1 antagonists
Ach muscarinic receptor
Stimulates proton pump in parietal cell (drug targets this more)
Contractions of smooth muscle cells (drug targets this less)
Used for chronic acid produce with or without ulcer
Pirenzipine
Laxatives
Constipation managements
Contraindication for many GIT pathology
Osmotic laxatives
Non-absorbable inorganic salts (Mg and sulfate ions) causes water retension
Stimulant laxatives
Affects wall of either small or large intestines by increasing peristaltic movements, sense of urgency
Examples: bisacodyl, sennosides, sodium picosulfate
Faecal softeners
Act on intestinal wall to inhibit water absorption and promate water and electrolyte secretion
Example: docusate
Lubricants
Mineral oils such a liquid paraffin
Water absorption prevented by hydrophobic properties
Can interfere with absorption of fat- soluble vitamins
