Pharmacology & Anesthesia: Antimotility (Antidiarrheal) Agents

First-Line Antimotility Agents

Loperamide (Imodium)

  • Mechanism of Action: Intestinal Opioid Agonist to Inhibit Peristalsis
  • Dosing: 4 mg PO
    • Additional 2 mg After Each Loose Stool
    • Maximum 16 mg/Day (May Require Higher Doses in Select Cases)
  • Side Effects:
    • Constipation
    • Abdominal Pain/Cramps
    • Nausea & Vomiting
    • Dizziness
  • *Generally Preferred First Medication (Lower Side Effects)

Diphenoxylate-Atropine (Lomotil)

  • Mechanism of Action:
    • Diphenoxylate: Intestinal Opioid Agonist to Inhibit Peristalsis
    • Atropine: Anticholinergic
  • Dosing: 5 mg/0.05 mg (2 Tablets or 10 cc) 4-Times per Day
    • Maximum 20 mg/0.2 mg per Day (8 Tablets or 40 cc)
  • Side Effects:
    • Constipation
    • Abdominal Pain/Cramps
    • Nausea & Vomiting
    • Dizziness
    • Additional Anticholinergic Effects:
      • Hyperthermia
      • Flushing
      • Tachycardia
      • Confusion
      • Dizziness
      • Headache
      • Sedation & Lethargy
      • Pruritis & Urticaria
      • Urinary Retention

Soluble Fiber Supplements

Second/Third-Line Antimotility Agents

Bismuth Subsalicylate (Pepto-Bismol)

  • Mechanism of Action: Intestinal Antimicrobial & Antisecretory Action
  • Dosing: 524 mg Every 30-60 Minutes as Needed
    • Maximum 4,200 mg per Day

Tincture of Opium

  • Mechanism of Action: Intestinal Opioid Agonist to Inhibit Peristalsis
  • Dosing: 6 mg 4 Times Daily
  • Potentially Addicting

Codeine

  • Mechanism of Action: Intestinal Opioid Agonist to Inhibit Peristalsis
  • Dosing: 30-60 mg 3-4 Times per Day
  • Potentially Addicting

Octreotide

  • Mechanism of Action: Mimics Somatostatin to Inhibit Secretin & Motilin
  • Dosing: 100-150 mcg 3 Times per Day
    • Subcutaneous or IV
    • Can Increase to 500-2,000 TID
  • Numerous Other Associated Side Effects

Cholestyramine (Questran)

  • Mechanism of Action: Binds Intestinal Bile Acids to Inhibit Reuptake
  • Dosing: 2-4 g per Day PO
    • Maximum 24 g per Day
  • Used for Chronic Diarrhea Due to Bile Acid Malabsorption

PPI/H2-Blockers