Gastrointestinal Agents Flashcards
Aluminum Hydroxide, Magnesium Hydroxide, Calcium Carbonate, Sodium Bicarbonate
Peptic Ulcer Disease Agents. Antacids.
Weak bases that react with gastric HCl to form H2O and salt. Net result is increased stomach pH, can deactivate pepsin (pH > 4) and decrease protein breakdown. May increase mucosal barrier by stimulating prostaglandin synthesis.
Rx of GERD, promotes healing of duodenal ulcers. SE below.
Ex: Aluminum Hydroxide (constipation), Magnesium Hydroxide (diarrhea), Calcium Carbonate (hypercalcemia, milk-alkali syndrome), Sodium Bicarbonate (flatulence, metabolic alkalosis).
Sucralfate
Peptic Ulcer Disease Agent.
May enhance mucosal barrier via prostaglandin synthesis or as a physical barrier itself. Promotes healing of duodenal ulcers.
Requires an acidic environment for activation, so not use with antacids, H2 blockers, or PPIs.
__tidine
Peptic Ulcer Disease Agents. Histamine Blockers.
Block binding of histamine from ECL cells to the H2 receptor in patietal cells. Decreases cAMP, leading to decreased H+/K+ proton pump activity, which means it decreases effect of gastrin and ACh too. Results in decreased gastric acid release.
Rx of GERD, peptic ulcer disease, gastric ulcers. SE: HA, gynecomastia, decreased hepatic metabolism of drugs (Cim). Usually PPI used.
Ex: Ranitidine, Cimetidine, Famotidine, Nizatidine.
__prazole
Peptic Ulcer Disease Agents. Proton Pump Inhibitors.
Directly bind and inhibit the H+/K+ ATPase proton pump in gastric mucosa parietal cells. Results in decreased gastric acid release.
Rx of GERD, peptic ulcer disease, Zollinger-Ellison syndrome, esophagitis, part of H. pylori regimen. SE: HA, rash, increased risk for fractures in elderly.
Ex: Omeprazole, Lansoprazole, Rabeprazole, Pantoprazole, Esomeprazole.
Ondansetron
Antiemetic Agent.
Inhibits vomiting reflex pathway by blocking 5-HT3 receptors in the chemoreceptor trigger zone of brainstem and GI tract. Damaged enterochromaffin cells release serotonin and activate 5-HT3 receptors in GI, which via vagus nerve signals the brainstem to activate vomiting reflex pathway.
Rx of nausea and vomiting associated with chemo or surgery. SE: HA.
Metoclopramide, Prochlorperazine
Antiemetic Agents.
Dopamine antagonists that prevent activation of vomiting reflex. Activated D2 receptors in the chemoreceptor trigger zone can activate the vomiting reflex pathway.
Rx of nausea and vomiting associated with chemo or surgery. SE: sedation, hypotension, diarrhea, extrapyramidal symptoms.
Promethazine
Antiemetic Agent.
H1 receptor antagonist. H1 receptors are throughout the body (including GI) and when blocked GI tract motility is decreased.
Rx of nausea and vomiting associated with chemo or surgery. SE: blurry vision, confusion, dry mouth.
Other drugs for chemo n/v: Haloperidol, Benzodiazepines, Corticosteroids, Marijuana.
1 - Castor oil, Senna, Bisacodyl. 2 - Lactulose, Sorbital, Polyethylene glycol, Magnesium salts. 3 -Docusate, Mineral oil.
Laxatives.
Irritants and Stimulants: Increase intestinal peristalsis and gut motility. Castor oil, Senna, Bisacodyl.
Bulking: draw H2O into intestines via osmosis, distending the bowel which increases intestinal motility. Lactulose, Sorbital, Polyethylene glycol, Magnesium salts.
Stool Softeners: become emulsified with stool. Docusate, Mineral oil.
Rx for constipation, bowel preparation for colonoscopy. SE: abdominal cramps.
Diphenoxylate, Loperamide, Kaolin, Bismuth subsalicylate
Antidiarrheal Agents
Diphenoxylate, Loperamide: bind opioid receptors in intestine, leading to inhibited ACh release, resulting in decreased peristalsis.
Kaolin: absorbs intestinal toxins, but not very effective.
Bismuth subsalicylate: treats traveler’s diarrhea by decreasing secretion of fluid into the bowel lumen.
__salazine
Gastointestinal Agent.
Overall an anti-inflammatory by inhibiting COX. In colon, 2 metabolites formed.
5-ASA: inhibits prostaglandin and leukotriene production via COX inhibition.
Sulfapyridine: impairs folic acid absorption, so give with FA supplement.
Rx of IBD, RA, juvenile arthritis. SE: GI upset, rash, HA, bone marrow suppression, infertility.
Ex: Sulfasalazine, Olsalazine.
__odiol
Gastointestinal Agent.
Decreases incidence of cholesterol gallstones by:
Inhibiting HMG-CoA reductase (decreasing cholesterol synthesis).
Decreasing intestinal reabsorption of cholesterol.
Inhibiting the secretion of cholesterol into bile.
Rx of primary billiary cirrhosis, cholesterol gallstones (instead of cholecystectomy). SE: GI upset.
Ex: Ursodiol, Chenodiol.
