Source / episode info

• **Episode:**10
• **Title:**Divine Intervention Episode 10 – Comprehensive GI Pharmacology.
• **Published:**2018-03-24
• Source:Episode page

One-liner

Episode 10 provides a comprehensive review of GI pharmacology, covering laxatives (CaCO_3, Al(OH)_3), anti-emetics (5-HT_3 antagonists, D2 blockers), acid secretion physiology and inhibitors (H2 blockers, PPIs), management of hepatic encephalopathy, and autoimmune biliary diseases (PBC/PSC).

High-yield summary

• Acid Secretion: Acid release is stimulated by Acetylcholine ({M}_3 receptors) and Gastrin (via CCKBR and histamine release); the final common pathway involves increasing intracellular cAMP.
• PPIs vs H2 Blockers: PPIs irreversibly inhibit the {H}^+/{K}^+ ATPase pump, making them the most potent acid suppressants; they carry risks of B12 deficiency (due to reduced pepsin activity), hypomagnesemia, and increased risk of infections/fractures.
• GI Motility Agents: Prokinetics include cholinergic agonists (Bethanechol) or AChE inhibitors (Neostigmine); motility can also be stimulated by {M}_3 receptor agonists (e.g., Bethanechol).
• Hepatic Encephalopathy: Treatment involves reducing ammonia load via Lactulose (acidifies gut, trapping {NH}_3 as non-absorbable {NH}_4^+) or using Rifaximin (non-absorbable antibiotic that reduces gut flora).
• Autoimmune Cholangitis: Primary Biliary Cholangitis (PBC) is associated with anti-mitochondrial antibodies ({AMA}) and treated with Ursodeoxycholic acid (UDCA); Primary Sclerosing Cholangitis (PSC) is associated with {p}-ANCA.

Learning objectives

• Differentiate between various GI laxatives based on their mechanism of action (osmotic, bulk-forming, etc.).
• Describe the physiological pathways regulating gastric acid secretion and identify key pharmacological targets (\text{H}_2 receptors, \text{H}^+/\text{K}^+ ATPase).
• Apply knowledge of PPI side effects, particularly B12 deficiency, hypomagnesemia, and fracture risk.
• Outline the management strategies for hepatic encephalopathy using lactulose or rifaximin.
• Distinguish between autoimmune cholangitis patterns (PBC vs PSC) based on antibody profile and treatment.

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