Epidemiology
Etiology
Pathophysiology
Clinical features
Diagnostics
Treatment
Approach
- First-line: nonpharmacological measures (e.g., high-fiber diet, increased fluid intake, and exercise) and/or trial of bulk-forming laxatives
- Second-line: step-wise pharmacotherapy with laxatives from other classes
- Begin with an osmotic laxative.
- If symptoms persist, add a short course of a stimulant laxative.
Laxatives
- Bulk-Forming
- Psyllium, Methylcellulose
- ↑ stool mass → stimulates peristalsis
- Onset: 12-72h
- SE: Bloating; needs water to prevent obstruction
- Osmotic
- Lactulose (also for hepatic encephalopathy), Polyethylene glycol (PEG), Mg(OH)₂
- Draw water into lumen
- PEG: First-line for chronic constipation; safe, effective, well-tolerated
- Onset: 0.5-3h (saline), 24-48h (lactulose)
- SE: Dehydration, electrolyte loss; Mg²⁺ toxicity in renal failure
- Stimulant
- Bisacodyl, Senna
- Stimulate enteric nerves → ↑ peristalsis
- Onset: 6-12h (oral), 15-60min (rectal)
- SE: Cramping; chronic use → melanosis coli, cathartic colon
- Stool Softeners
- Docusate
- Detergent allows water penetration
- Use: Prevent straining post-op, post-MI
- Lubricant
- Mineral oil
- SE: Lipid pneumonia (aspiration), ↓ fat-soluble vitamin absorption
- Secretagogues
- Lubiprostone (ClC-2 activator), Linaclotide/Plecanatide (GC-C agonists)
- ↑ intestinal fluid secretion
- Use: IBS-C, chronic constipation
- Opioid Antagonists
- Methylnaltrexone, Naloxegol
- Block peripheral μ-receptors (don’t cross BBB)
- Use: Opioid-induced constipation