Appetite Stimulants/Gastric Ulcer Pharmacology

Indications for appetite stimulants

Animals presenting with anorexia or hyporexia

Describe the stomach-hypothalamus signal that induces hunger

Ghrelin (originating in the stomach) travels through blood and interacts with GHS-receptor in the hypothalamus to increase appetite

What is the drug target that stimulates hunger?

GHS-R (growth hormone secretagogue receptor)

What is the satiety hormone and where does it originate?

Leptin, fat tissue

What are other positive effects of serotonin receptor antagonists that stimulate hunger and how are these effects mediated?

Increased appetite

Anti-depressant

Anti-nausea (alpha-2 adrenergic antagonist)

MOA of capromorelin

Appetite stimulants at hunger center in hypothalamus

• Acts at GHS-R to mimic Ghrelin

Which drug class are mirtazapine and cyproheptadine?

Appetite stimulants: serotonin antagonists

• 5-HT₃ receptor antagonist

• H1 Histamine antagonist

What do H₂ histamine receptor blockers and proton pump inhibitors do?

Reduce gastric acid secretion for ulcer care

What do prostaglandin E2 (and I2) and sucralfate do?

Gastric anti-secretory and cytoprotective agent for ulcer care

MOA of H2-receptor antagonists

• Competitively inhibit interaction of histamine ONLY with the H2 receptor on parietal cells → block stimulation of H+ release (and subsequent HCl formation)

List examples of H2 antagonists

“-tidine”

• Famotidine (pepsid)

• Cimetidine (tagemet)

• Ranitidine (zantac)

MOA of proton pump inhibitors

• Binds to H-K-ATPase irreversibly to block H+ secretion by parietal cells

• Requires acidic environment to be effective, so MUST be given before eating

List examples of proton pump inhibitors

“-prazole”

• Omeprazole (gastroguard)

• Esomeprazole (nexium)

• Pantoprazole

MOA of PGE₂ and PGI₂

• Binds to PG receptors on parietal cells and superficial epithelial cells to block H+ release into gut lumen

  • Inhibit acid secretion

  • Stimulate mucus and bicarbonate secretion

  • Enhance local blood flow

  
  

Examples of prostaglandins?

• Misoprostol

• Synthetic PGE₁₊₂

MOA of sucralfate

• Forms sticky, viscous gel in pH<4

• “Bandaid” → binds to raw/damaged epithelium