Drugs Acting on the Digestive System Cheat Sheet

Key Definitions

• Antacids: Substances that neutralize stomach acid. ✅

• Laxatives: Drugs that relieve constipation by promoting bowel movements. ✅

• Antidiarrheals: Medications that reduce diarrhea by slowing intestinal movement. ✅

Important Concepts

Types of Drugs

• Proton Pump Inhibitors (PPIs): Reduce stomach acid production.

• H2-receptor antagonists: Block histamine receptors to decrease acid secretion.

• Bulk-forming laxatives: Increase stool bulk by absorbing water.

Mechanism of Action

• Antacids: Neutralize gastric acid to relieve heartburn.

• Laxatives: Stimulate intestinal motility or soften stool.

• Antidiarrheals: Decrease peristalsis in the intestines.

Key Formulas

• HA: Acid (e.g., HCl)

• BOH: Base (e.g., Mg(OH)2)

• BA: Salt formed from the reaction

Common Mistakes to Avoid

Common Mistake: Confusing laxatives with antidiarrheals; they serve opposite functions.

Memory Tricks

Tip: "PAB" — Proton Pump Inhibitors, Antacids, Bulk-forming laxatives.

Key Diagrams

           +-------------+
           |   Stomach   |
           +-------------+
               |   ^
               |   |
      +--------+   +---------+
      | Antacids (Neutralize)|
      +----------------------+

           +-------------+
           |   Intestine  |
           +-------------+
               |   ^
               |   |
      +--------+   +---------+
      | Laxatives (Stimulate)|
      +----------------------+