GI Pharmacology Flashcards

Flashcards covering key pharmacology concepts for gastrointestinal disorders, including medications for PUD, GERD, constipation, emesis, and IBD.

Prostaglandins (GI Defense)

Lipid compounds in the stomach that suppress gastric acid secretion, stimulate secretion of protective mucus and bicarbonate, and promote vasodilation to maintain mucosal blood flow.

Helicobacter pylori (H. pylori)

A bacterium that colonizes the gastric mucosa and promotes peptic ulcer disease through direct enzymatic mucosal damage and urease secretion.

Bismuth subsalicylate (Pepto-Bismol)

An anti-ulcer agent that disrupts bacterial cell walls, provides anti-inflammatory action via its salicylate component, and causes harmless grey/black discoloration of stool and tongue.

Histamine 2 Receptor Antagonists (H2RAs)

A drug class ending in '-idine' (e.g., famotidine, cimetidine) that selectively blocks H2 receptors on parietal cells, reducing gastric acid and hydrogen ion secretion.

Tachyphylaxis

A rapid decrease in response to a drug after repeated administration; occurs with H2RAs within 2 to 6 weeks of starting treatment.

Misoprostol (Cytotec)

A synthetic prostaglandin E1 analog that binds parietal cell receptors to suppress acid secretion; used to prevent NSAID-induced ulcers, but strictly contraindicated in pregnancy.

Proton Pump Inhibitors (PPIs)

Pro-drugs ending in '-prazole' (e.g., omeprazole, pantoprazole) that irreversibly inhibit the $H^+, K^+\text{-ATPase}$ enzyme system in gastric parietal cells.

Sucralfate (Carafate)

A complex sucrose-aluminum compound that polymerizes into a sticky gel in acidic stomach conditions, forming a physical protective barrier over ulcers.

Osmotic Laxatives

Poorly absorbed salts or carbohydrates (e.g., magnesium hydroxide, MiraLax) that draw water into the bowel lumen, expanding feces and stimulating peristalsis.

Bulk-Forming Laxatives

Non-digestible polysaccharides or cellulose compounds (e.g., psyllium) that absorb water to form a gel, increasing stool mass and triggering bowel stretch reflexes.

Surfactant Laxatives

Agents such as docusate sodium (Colace) that lower the surface tension of stool, allowing water and lipids to penetrate the fecal mass while inhibiting colon water reabsorption.

Stimulant Laxatives

Drugs (e.g., bisacodyl, senna) that directly stimulate intestinal mucosa and smooth muscle motility while increasing fluid secretion into the intestinal lumen.

Chemoreceptor Trigger Zone (CTZ)

An area located in the brainstem outside the blood-brain barrier that detects circulating emetic agents (like chemotherapy or opioids) and signals the medullary vomiting center.

Ondansetron (Zofran)

A serotonin $5\text{-HT}_3$ receptor antagonist that suppresses emesis by blocking serotonin in the CTZ and vagal afferents; side effects include dizziness and risk of Torsades de pointes.

Metoclopramide (Reglan)

A dual serotonin and dopamine antagonist in the CTZ that suppresses vomiting and promotes upper GI motility; long-term use risks extrapyramidal effects such as tardive dyskinesia.

Scopolamine (Scopoderm)

An anticholinergic agent that blocks muscarinic pathways from the inner ear vestibular apparatus to the vomiting center; used primarily for motion sickness.

Sulfasalazine (Azulfidine)

A 5-aminosalicylate drug used in inflammatory bowel disease that inhibits cyclooxygenase to reduce prostaglandin synthesis and mucosal inflammation.

Infliximab (Remicade)

An intravenous monoclonal antibody that neutralizes TNF-$\alpha$ to reduce inflammation in IBD; increases patient risk for severe infections like tuberculosis.

Adalimumab (Humira)

A subcutaneously injected TNF-$\alpha$ inhibitor monoclonal antibody used for inflammatory bowel disease; requires rotation of injection sites.

Cyclosporine (Neoral)

An oral immunosuppressive agent that blocks interleukin production to inhibit B cell and T cell proliferation; carries a key adverse risk of nephrotoxicity.