Macrogol / Polyethylene glycol
Bowel cleansing solutions contain **polyethylene glycol (macrogol)** as an osmotic laxative and balanced electrolytes to maintain isotonicity and prevent net fluid loss or gain. When administered orally, they rapidly empty the bowel. > **Clinical Pearl:** Commonly used for bowel preparation prior to colonoscopy, gastrointestinal radiography, or surgery, and occasionally for the management of severe refractory constipation or fecal impaction.
Mechanism: **Polyethylene glycol** acts as an **osmotic laxative**. It is a large, non-absorbable polymer that binds water → retains fluid within the colonic lumen → increases fecal volume and softens stool → stimulates colonic motility and peristalsis → rapidly empties the bowel. The addition of balanced electrolytes ensures isotonicity, preventing significant shifts of sodium, potassium, or water across the intestinal mucosa.
Routes of administration
Contraindications
- Gastrointestinal obstruction
- Bowel perforation
- Gastric retention
- Toxic megacolon
- Severe dehydration
Adverse effects
- Nausea
- Vomiting
- Abdominal cramping
- Bloating
- Fluid and electrolyte imbalances (rare if formulated with electrolytes)
Drug interactions
- Oral medications · Decreased absorption due to rapid gastrointestinal transit time · moderate
Monitoring
- Fecal output and consistency
- Hydration status
- Serum electrolytes (in prolonged or high-dose use)
Overdose
Overdosage may result in severe diarrhea, leading to significant fluid and electrolyte loss. Treatment is primarily supportive, focusing on intravenous fluid therapy to restore hydration and correct any electrolyte derangements.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.