Medicine & USMLE


GI Drugs
  1. Ondansetron
  2. Sucralfate
  3. Docusate (Stool Softener)
  4. Bulk Forming Laxatives (Psyllium, Methylcellulose)
  5. Osmotic Laxatives (Lactulose, PEG)
  6. Stimulant Laxatives (Senna, Bisacodyl)
  7. Antidiarrheals (Loperamide, Diphenoxylate-Atropine)
  8. Bismuth Subsalicylate
  9. Antacids
  10. Proton Pump Inhibitors (PPIs)
  11. H2 Blockers
  12. Metoclopramide
  13. Misoprostol
  14. Orlistat
  15. Octreotide


Orlistat is a weight loss medication that works by reducing fat absorption in the gut. Side effects include steatorrhea, or fatty, greasy stools. Orlistat also can cause vitamin deficiencies of the fat-soluble vitamins A, D, E, and K. These vitamins should be supplemented during orlistat treatment.

Key Points

  • Orlistat (Xenical)
    • Mechanism
      • Lipase inhibitor
        • Reduces GI fat absorption
    • Clinical Use
      • Weight loss
        • To be taken with meals
    • Side Effects and Adverse Reactions
      • Steatorrhea
        • Fatty, oily bowel movements due to reduced GI fat absorption (more fat in feces)
        • Patients may be prescribed psyllium to reverse adverse GI effects
      • Vitamin deficiency
        • Can reduce the absorption of fat-soluble vitamins like Vitamins A, D, E, and K
        • These vitamins should be supplemented in patients taking orlistat