MiraLAX and PEG 3350 Are the Same Medication
MiraLAX is simply the brand name for polyethylene glycol (PEG) 3350, making them chemically identical products with the same efficacy, safety profile, and mechanism of action. 1, 2
Understanding PEG 3350
Mechanism of Action
- PEG 3350 is a long-chain polymer of ethylene oxide that acts as an osmotic laxative
- It works by attracting water into the colon, which softens stool and increases bowel movements
- Unlike stimulant laxatives, it does not cause dependency or significant electrolyte disturbances
Formulation and Administration
- Standard dosage: 17g of powder dissolved in 8 ounces (240mL) of liquid once daily
- Can be mixed with water, juice, coffee, or tea at any temperature
- Available as:
- Brand name (MiraLAX) in powder form
- Generic PEG 3350 in identical formulation
- Some versions include electrolytes (PEG-E), though the standard U.S. formulation typically does not
Efficacy for Constipation
PEG 3350/MiraLAX has demonstrated significant efficacy in treating constipation:
- Increases complete spontaneous bowel movements (CSBMs) by approximately 2.9 per week compared to placebo 1
- Increases spontaneous bowel movements (SBMs) by approximately 2.3 per week 1
- Achieves success rates of 52% for chronic constipation versus 11% for placebo over 6 months 3
- Demonstrates superior efficacy compared to other medications like tegaserod 4 and comparable efficacy to prucalopride 5
Safety Profile
The safety profile of PEG 3350/MiraLAX is well-established:
- Well-tolerated with minimal side effects
- Common side effects include bloating, flatulence, abdominal discomfort, and loose stools
- No significant differences in laboratory findings compared to placebo in long-term studies 3
- Safe for use in elderly patients 3
- No risk of dependency or tolerance development
Duration of Use
- FDA-approved for short-term treatment of occasional constipation
- Clinical evidence supports safe and effective use for up to 6 months for chronic idiopathic constipation 1, 3
- The American Gastroenterological Association suggests it can be used earlier in the treatment algorithm for chronic idiopathic constipation, either after a trial of fiber supplementation or in combination with fiber 1
Cost Considerations
- Generally more cost-effective than prescription constipation medications
- Available over-the-counter, eliminating the need for prescription costs
- Monthly cost ranges from $10-$45 depending on brand versus generic 2
Clinical Applications
PEG 3350/MiraLAX is recommended for:
- Chronic idiopathic constipation (CIC) 1
- Irritable bowel syndrome with constipation (IBS-C), though evidence is limited 1
- Medication-induced constipation 2, 6
Important Considerations
- Higher doses (51-85g) may provide more rapid relief within 24 hours for acute constipation 7
- Standard 17g dose typically produces effects within 2-4 days of regular use
- Avoid use in patients with known or suspected bowel obstruction
- No significant drug interactions have been reported
Remember that while MiraLAX is a brand name and PEG 3350 is the generic name, they contain the same active ingredient and work through the same mechanism, making them therapeutically equivalent.