Polyethylene glycol 3350 - Drug Monograph

Introduction

Polyethylene glycol 3350 (PEG 3350) is an osmotic laxative medication used primarily for the treatment of occasional constipation. It is a high-molecular-weight polymer of ethylene oxide that works by drawing water into the colon to soften stool and promote bowel movements. Unlike many other laxatives, PEG 3350 is not systemically absorbed and is generally well-tolerated, making it a first-line agent for constipation management in both adults and pediatric populations.

Mechanism of Action

PEG 3350 exerts its therapeutic effect through osmotic activity in the gastrointestinal tract. The polymer is not absorbed from the intestinal lumen and creates an osmotic gradient that draws water into the colon through passive diffusion. This increased water content softens the stool, increases stool volume, and enhances peristalsis, thereby facilitating bowel movement without stimulating intestinal nerves or altering normal electrolyte balance.

Indications

• Treatment of occasional constipation
• Management of chronic constipation (off-label)
• Bowel preparation for diagnostic procedures (in combination with electrolytes)
• Maintenance therapy for constipation in special populations (e.g., elderly, patients with opioid-induced constipation)

FDA-approved for adults and children 6 months and older for the treatment of occasional constipation.

Dosage and Administration

• Dissolve powder completely in 4-8 ounces of liquid
• Administer once daily
• Onset of action typically within 24-72 hours
• May take 2-4 days for optimal effect

• Renal impairment: Use with caution
• Hepatic impairment: No dosage adjustment required
• Elderly: No dosage adjustment required
• Pregnancy: Category C - use if clearly needed

Pharmacokinetics

Contraindications

• Known hypersensitivity to polyethylene glycol
• Gastrointestinal obstruction
• Bowel perforation
• Toxic megacolon
• Ileus
• Severe inflammatory conditions of the intestinal tract (e.g., Crohn's disease, ulcerative colitis)

Warnings and Precautions

• Use with caution in patients with impaired gag reflex or prone to regurgitation/aspiration
• Monitor for signs of electrolyte imbalance in patients using prolonged therapy
• Avoid use in patients with nausea, vomiting, or abdominal pain until etiology determined
• Use caution in patients with renal impairment due to potential for electrolyte disturbances
• Discontinue use if severe diarrhea, abdominal cramping, or pain occurs

Drug Interactions

• May reduce absorption of other orally administered medications due to accelerated gastrointestinal transit time
• Separate administration from other medications by at least 2 hours
• No clinically significant pharmacokinetic interactions (due to lack of systemic absorption)

Adverse Effects

• Abdominal bloating
• Flatulence
• Nausea
• Abdominal cramping
• Diarrhea (especially with higher doses)

• Vomiting
• Dizziness
• Urticaria
• Rash

• Anaphylactic reactions
• Severe electrolyte disturbances
• Aspiration pneumonia (particularly in elderly or debilitated patients)

Monitoring Parameters

• Bowel movement frequency and consistency
• Hydration status
• Electrolytes (with prolonged use or in at-risk populations)
• Signs of allergic reactions
• Abdominal examination findings
• Patient weight (in pediatric patients)

Patient Education

• Take exactly as directed; do not exceed recommended dosage
• Maintain adequate fluid intake during therapy
• Allow 2-4 days for full therapeutic effect
• Separate administration from other medications by at least 2 hours
• Report severe abdominal pain, rectal bleeding, or persistent constipation
• Not for long-term use without medical supervision
• Store at room temperature away from moisture
• Dissolve completely in liquid before consumption
• Seek medical attention if no bowel movement occurs after use

References

1. American Gastroenterological Association. (2013). Guidelines on the management of chronic constipation. Gastroenterology, 144(1), 211-217. 2. Brenner, D. M., & Shah, M. (2016). Chronic constipation. Gastroenterology Clinics, 45(2), 205-216. 3. Ford, A. C., et al. (2014). Efficacy of laxatives in chronic constipation: systematic review and meta-analysis. American Journal of Gastroenterology, 109(2), 158-168. 4. Lee-Robichaud, H., et al. (2011). Lactulose versus polyethylene glycol for chronic constipation. Cochrane Database of Systematic Reviews, (7). 5. Micromedex Solutions. (2023). Polyethylene glycol 3350 drug monograph. 6. Phatak, U. P., & Pashankar, D. S. (2014). Role of polyethylene glycol in childhood constipation. Clinical Pediatrics, 53(10), 927-932. 7. US Food and Drug Administration. (2023). Prescribing information for polyethylene glycol 3350. 8. von Volkmann, R. (2015). The safety and efficacy of polyethylene glycol 3350 in the treatment of constipation. Journal of Clinical Gastroenterology, 49(2), 99-103.