What to do for constipation after no bowel movement in one week with Miralax (polyethylene glycol) treatment?

Management of Constipation After One Week Without Bowel Movement Despite Miralax Treatment

For a patient who has not had a bowel movement in one week despite using Miralax (polyethylene glycol), you should increase the Miralax dosage to 1 capful/8 oz water twice daily and add a stimulant laxative such as bisacodyl 10-15 mg daily. 1

Initial Assessment

• Rule out impaction by performing a digital rectal examination to assess pelvic floor motion during simulated evacuation 1
• Check for obstruction through physical examination and consider abdominal x-ray if symptoms are severe 1
• Evaluate for other causes of constipation such as hypercalcemia, hypokalemia, hypothyroidism, diabetes mellitus, or medication side effects 1
• Review and discontinue any non-essential constipating medications (antacids, anticholinergics, antidepressants, antispasmodics, phenothiazines, haloperidol, antiemetics) 1

Immediate Management

• Increase polyethylene glycol (Miralax) dosage to 1 capful/8 oz water twice daily 1, 2
• Add a stimulant laxative such as bisacodyl 10-15 mg daily-TID with a goal of achieving one non-forced bowel movement every 1-2 days 1
• Ensure adequate fluid intake and encourage physical activity if appropriate 1
• Consider dietary modifications including increased fiber intake if patient has adequate fluid intake 1

If No Response Within 24-48 Hours

• Consider administering a glycerine suppository or bisacodyl suppository (one rectally daily-BID) 1
• Evaluate for fecal impaction; if present, consider manual disimpaction following pre-medication with analgesic ± anxiolytic 1
• Consider adding other laxative options:
  • Lactulose, 30-60 mL BID-QID 1
  • Sorbitol, 30 mL every 2 hours × 3, then as needed 1
  • Magnesium hydroxide, 30-60 mL daily-BID 1
  • Magnesium citrate, 8 oz daily 1

For Severe or Persistent Constipation

• Consider a higher dose of polyethylene glycol - studies have shown that doses up to 68g (approximately 4 capfuls) can be effective and safe for severe constipation 2, 3
• For opioid-induced constipation that doesn't respond to standard laxative therapy, consider methylnaltrexone 0.15 mg/kg subcutaneously every other day (no more than once daily) 1
• Consider tap water enema until clear if other measures fail 1
• If gastroparesis is suspected, add a prokinetic agent such as metoclopramide 10-20 mg PO QID 1

Important Considerations

• Bisacodyl should not be used for longer than one week without medical supervision 4
• Polyethylene glycol alone may not provide lasting effectiveness for chronic constipation; combination therapy is often needed 5
• If constipation persists despite appropriate treatment, consider referral for specialized testing such as colonic transit studies or anorectal manometry 1
• Be aware that diarrhea accompanying constipation may indicate overflow around impaction 1
• For patients with chronic constipation, newer agents such as lubiprostone or linaclotide may be considered if standard treatments fail 1, 6

Follow-up

• Reassess the patient within 24-48 hours to determine response to therapy 1
• If constipation resolves, continue maintenance therapy with the effective regimen for at least several days, then consider tapering 1
• If symptoms persist despite escalation of therapy, consider specialized gastroenterology consultation 1