Question

Explain why NSAIDs can increase acid secretion from parietal cells.

Answer 1

Ans) Prostacyclin production in the stomach stimulates mucus/bicarbonate production and inhibits stomach acid production. NSAIDS inhibit PG synthesis => more acid and less mucus is produced => ulcer.

- The mechanisms of action of histamine2 receptor blockers AND where in the parietal cell these actions occur.

Promote ulcer healing via suppressing secretion of gastric acid.
--> Block histamine receptors on parietal cells

Types:
Cimetidine
Reduces volume of gastric juice & hydrogen ion concentration
Ranitidine
More potent & produces less adverse effects than Cimetidine
Blocks H2 receptors on gastric parietal cells
Famotidine
Nizatidine

Newer agents have fewer side effects.

- Most effective drugs for suppressing gastric acid secretion. Can increase risk of serious adverse events (fractures, pneumonia, acid rebound, intestinal infection with C. difficile).
--> block the gastric H,K-ATPase, inhibiting gastric acid secretion

Types:
Omeprazole (Prilosec)
--> Irreversible inhibition of H+,K+ ATPase (proton pump that generates gastric acid)
--> Adverse effects: Headache, dizziness
GI - diarrhea, nausea, constipation, abdominal pain, vomiting
--> Work best when taken continuously. Administered before meals - if bid before breakfast and dinner.
Lansoprazole (Prevacid)
Esomeprazole (Nexium)
Pantoprazole (Protonix)
Rabeprazole (Aciphex)

PPIs risk of Clostridium difficile-associated diarrhea.