GI Pharm Flashcards
Goals of GI Pharmacology
Food digestion, nutrition and water absorption, gastric acid control and secretion, manage excessive GI motility (diarrhea), manage inadequate bowel evacuation (constipation), manage problems with digestion and vomiting (emesis).
Main GI disorders treated
Ulcers, GERD, diarrhea, constipation, emesis.
Role of gastric acid
Essential for digestion, can cause peptic ulcers and GERD if uncontrolled.
Peptic ulcers and GERD
Peptic ulcers: ulceration of the mucosal lining. GERD: gastroesophageal reflux disease, caused by leaking of gastric acid.
Antacids - Goal
Neutralize stomach acids by combining with excess H+ to increase gastric pH.
Antacids - Specific agents
Various OTC trade names (TUMS, Pepto-Bismol).
Antacids - Adverse effects
Constipation (Al-containing), diarrhea (Mg-containing), electrolyte imbalances, altered pharmacokinetics of medications.
H2 Receptor Blockers - Role of histamine
Stimulates H2 receptors in stomach to increase gastric acid secretion.
H2 Receptor Blockers - Goal
Bind to H2 receptors to avoid activation and prevent histamine-activated release of gastric acid.
H2 Receptor Blockers - Specific agents
Famotidine (Pepcid), Cimetidine (Tagamet), Nizatidine (Axid), Ranitidine (Zantac).
H2 Receptor Blockers - Adverse effects
Headache, dizziness, mild GI problems (nausea, diarrhea, constipation), acid-rebound phenomenon.
Proton Pump Inhibitors - Goal
Inhibit enzyme (proton pump) involved in secretion of acid from gastric cells.
Proton Pump Inhibitors - Specific agents
Omeprazole (Prilosec), Pantroprazole (Protonix), Esomeprazole (Nexium), Lansoprazole (Prevacid), Dexlansoprazole (Kapidex).
Proton Pump Inhibitors - Adverse effects
Acid rebound, gastric polyps (long-term use), decrease nutrient absorption, kidney problems.
Anticholinergics
Blocks effects of acetylcholine and decrease gastric acid release, examples: Atropine, pirenzepine, telenzepine.
Metoclopramide (Reglan)
Dopamine receptor antagonist, stimulates motility in upper GI and decreases GERD.
Prostaglandins
Inhibit gastric secretion, no advantages over other drugs such as PPI.
Sucralfate (Carafate)
Disaccharide with protective effects on stomach mucosa, forms a protective gel that shields the stomach lining.
Antidiarrheal Agents - Goal
Decrease GI motility to reduce fluid loss.
Antidiarrheal Agents - Specific agents
Opium Tincture (laudanum), camphorated opium tincture (paregoric), Diphenoxylate (Lomotil), Loperamide (Imodium).
Antidiarrheal Agents - Adverse effects
Nausea, abdominal discomfort, constipation, drowsiness, fatigue, dizziness, smaller risk of tolerance and addiction with small doses.
Bismuth Salicylate
Stimulates water and electrolyte absorption in lower GI, decreases secretions, antibacterial effects.
Bile-sequestering agents
Sequester and bind bile acids within GI tract, examples: Cholestyramine (Questran), Colestipol (Colestid), Colesevelam (Welchol).
Clonidine (Catapres)
Stimulates alpha-2 receptors in GI tract, increases absorption and normal GI movement.
Laxatives and Cathartics - Overview and goals
Promote evacuation of bowel and defecation when normal bowel movements are impaired, cathartics promote lower GI evacuation more rapidly than standard laxatives.
Bulk-forming laxatives
Absorb water and swell within GI tract, stretches the bowel and stimulates intestinal movement.
Stimulant laxatives
Increase fluid accumulation within the small intestine or activate peristalsis, examples: Bisacodyl (Dulcolax), Castor Oil, Senna (Senokot).
Hyperosmotic laxatives
Produce gradient that draws water into the bowel and small intestine, stimulates peristalsis, examples: Methylcellulose (Citrucel), Polycarbophil (Fiber Lax), Psyllium (Metamucil).
Lubricants and stool softeners
Facilitate entry of water into the fecal mass, softens the stool for easier defecation, examples: Docusate (Colace), Mineral Oil (Fleet Mineral Oil).
Adverse effects of laxatives
GI disturbances, nausea, cramps, GI irritation, spastic colitis, long-term use can cause fluid and electrolyte abnormalities, dehydration, acid-base imbalances, laxative dependence.
Digestants
Aid in digestion of food, examples: Pancreatic enzymes (amylase, trypsin, lipase), bile salts.
Emetics
Induce vomiting to empty stomach of poisons or ingested toxins, examples: Apomorphine, Ipecac.
Antiemetics
Decrease nausea and vomiting, examples: Antihistamines, anticholinergics, used for motion sickness, surgery recovery, chemo/radiation.
Cholelitholytic agents
Dissolve types of gallstones by decreasing cholesterol content of bile.
Rehabilitation considerations - Common issues
Common among critically ill patients, stress-related damage, stress ulcerations, inactivity causes adverse GI effects.
Rehabilitation considerations - Impact on rehabilitation
Overall should not impair rehabilitation, some dizziness and fatigue, resolve uncomfortable symptoms to increase participation.
Rehabilitation considerations - Encouragement of use
Encourage use if symptoms occur.
