GI System Drugs Flashcards
Mechanism: Misoprostol
PGE1 analog:
- Increases production and secretion of gastric mucous barrier
- Decreases acid production
All antacids can cause ___
Hypokalemia
Class: Polyethylene glycol
Osmotic laxative
Class: Magnesium hydroxide
Antacid
Osmotic laxative
Mechanism:
Loperamide
Diphenoxylate (+ atropine)
Agonist at mu-opioid receptors → slows gut motility
Loperamide: Poor CNS penetration (low addictive potential)
Diphenoxylate: Slight diffusion across BBB (atropine added to reduce abuse)
Clinical use: Sulfasalazine
- Ulcerative colitis (UC)
- Crohn disease (colitis component)
Adverse effects: Ondansetron
- Headache
- Constipation
- QT interval prolongation
- Serotonin syndrome (when used with other serotonergic drugs)
Adverse effects: Stimulant laxative
Senna
- Diarrhea
- Melanosis coli (dark brown/black discoloration of colon due to pigment deposition in lamina propria)
Adverse effects: Osmotic laxatives
Magnesium hydroxide
Magnesium citrate
Polyethylene glycol
Lactulose
- Diarrhea
- Dehydration
- May be abused by bulimics
Adverse effects: Bulk-forming laxatives
Psyllium
Methylcellulose
- Bloating
Overuse: Calcium carbonate (antacid)
- Hypercalcemia (milk-alkali syndrome)
- Rebound acid increase
Clinical use: Octreotide
- Acute variceal bleeds
- Acromegaly
- VIPoma
- Carcinoid tumors
Adverse effects: PPIs
- C. difficile infection
- Pneumonia
- Decreaes serum Mg2+ with long-term use
Adverse effects: Misoprostol
- Diarrhea
- Contraindicated in women of childbearing potential (abortifacient)
Mechanism: Emollient laxative
Docusate
Osmotic draw into lumen → increases water absorption by stool
Adverse effects: Octreotide
- Steatorrhea
- Increase risk of cholelithiasis due to CCK inhibition
- Nausea
- Cramps
Clinical use: Ondansetron
- Controlling post-op vomiting
- Cancer chemotherapy
Adverse effects:
Loperamide
Diphenoxylate
- Constipation
- Nausea
Class: Senna
Stimulant laxative
Adverse effects: Orlistat
- Steatorrhea
- Decrease absorption of fat-soluble vitamins
Mechanism: Orlistat
Inhibits gastric and pancreatic lipase → decreases breakdown and absorption of dietary fats
Mechanism: H2 blockers
Cimetidine
Ranitidine
Famotidine
Nizatidine
Reversible block of histamine H2-receptors → decreasing H+ secretion by parietal cells
Mechanism: Stimulant laxative
Senna
Enteric nerve stimulation → colonic contraction