What are alternatives to Miralax (polyethylene glycol) for treating constipation?

Alternatives to Miralax for Constipation

For patients with constipation who cannot or prefer not to use Miralax (polyethylene glycol), several effective alternatives are available, with stimulant laxatives like senna being the first-line alternative based on current guidelines. 1

First-Line Alternatives

Stimulant Laxatives

• Senna: Recommended as a first-line alternative with conditional but supportive evidence 1
  • Start at a lower dose and increase as needed
  • Common side effects include abdominal pain and cramping
  • Can be used for longer periods, though most trials were conducted for 4 weeks 1

Other Osmotic Laxatives

• Lactulose: Effective osmotic laxative 1

  • Takes 2-3 days for onset of effect
  • May cause bloating, nausea, or abdominal discomfort
  • Not absorbed by the small bowel

• Magnesium salts (citrate, hydroxide): Effective osmotic agents 1, 2

  • Use with caution in patients with renal impairment due to risk of hypermagnesemia
  • Magnesium citrate: typically dosed at 8 oz daily 2

Second-Line Options (for those who don't respond to OTC agents)

Prescription Medications

• Linaclotide: Strongly recommended (moderate evidence) 1

  • FDA-approved for chronic idiopathic constipation in adults 3
  • Typical dose: 145 mcg once daily (72 mcg may be used based on tolerability) 3
  • Take on empty stomach, 30 minutes before first meal of the day
  • Main side effect is diarrhea

• Plecanatide: Strongly recommended (moderate evidence) 1

  • Similar mechanism to linaclotide
  • May cause diarrhea leading to discontinuation

• Prucalopride: Strongly recommended (moderate evidence) 1

  • Side effects include headache, abdominal pain, nausea, and diarrhea

• Lubiprostone: Conditionally recommended (low evidence) 1

  • Can be used as replacement or adjunct to OTC agents
  • Take with food and water to reduce nausea

Special Considerations

For Opioid-Induced Constipation

• Methylnaltrexone: 0.15 mg/kg subcutaneously every other day 1, 2

  • Do not use in patients with postoperative ileus or mechanical bowel obstruction
  • Specifically targets opioid-induced constipation without affecting pain control

• Consider adding a prokinetic agent like metoclopramide (10-20 mg PO QID) 2

Treatment Algorithm

1. Start with a stimulant laxative (senna) at a low dose and titrate up as needed

   • Goal: One non-forced bowel movement every 1-2 days 2

2. If inadequate response, add or switch to an osmotic laxative

   • Lactulose (30-60 mL BID-QID) or
   • Magnesium citrate (8 oz daily) 2

3. For persistent constipation, consider combination therapy

   • Stimulant + osmotic laxative

4. If OTC options fail, progress to prescription medications

   • Linaclotide, plecanatide, or prucalopride (strongest evidence) 1
   • Lubiprostone (moderate evidence) 1

5. For severe cases or impaction

   • Consider suppositories (bisacodyl) or small-volume enemas 1
   • Manual disimpaction may be necessary for severe impaction 1

Cautions and Contraindications

• Bulk laxatives: Not recommended for opioid-induced constipation 1
• Magnesium products: Avoid in renal insufficiency 2
• Enemas: Contraindicated in neutropenia, thrombocytopenia, recent colorectal surgery, or intestinal obstruction 1

Comparative Effectiveness

Studies have shown that stimulant laxatives like senna may be more effective than polyethylene glycol in certain populations, particularly those with motility issues 4. While polyethylene glycol works by drawing water into the stool to soften it, stimulant laxatives like senna directly increase colonic motility, which can be beneficial for patients with hypomotility 4.

Polyethylene glycol solutions remain highly effective and safe for chronic constipation 5, but the alternatives presented here provide options for patients who cannot tolerate or prefer not to use Miralax.