How is Microlax (bisacodyl) used to treat constipation?

Microlax (Bisacodyl) for Constipation Management

Bisacodyl suppositories (such as Microlax) are effective stimulant laxatives that should be used when oral laxative therapy fails or when rapid relief of constipation is needed. 1, 2

Mechanism and Formulation

• Bisacodyl is a polyphenolic compound that acts as a stimulant laxative with both motor and secretory effects on the colon
• Available as 10 mg suppositories for rectal administration 1
• Works more quickly than oral laxatives by directly stimulating rectal motility and softening stool 2

Indications for Use

Bisacodyl suppositories are indicated for:

1. Constipation that has not responded to oral laxative therapy
2. Situations requiring rapid relief of constipation
3. Prevention of fecal impaction
4. Short-term treatment of constipation 2

Administration Guidelines

• Insert one 10 mg suppository rectally
• Can be used once daily when needed
• Best used when a bowel movement is desired within a short timeframe (typically works within 15-60 minutes) 3
• For persistent constipation, may be used as part of a comprehensive regimen that includes oral laxatives 2

Efficacy

• Clinical trials show bisacodyl is significantly more effective than placebo in improving stool frequency (1.8 stools/day vs. 0.95/day with placebo) 3
• Improves stool consistency from "hard" to between "soft" and "well-formed" 3
• Real-world evidence suggests microenemas like Microlax provide greater ease of use, comfort, reliability, and safety compared to oral laxatives and other rectal suppositories 4

Place in Constipation Management Algorithm

1. First-line approach: Lifestyle modifications (adequate fluid intake, physical activity, dietary fiber) 5
2. Second-line: Oral laxatives (osmotic agents like PEG or stimulants like oral bisacodyl/senna) 2, 5
3. Third-line: Rectal interventions including bisacodyl suppositories when:
   • Oral treatments fail
   • Rapid relief is needed
   • Fecal impaction is present or suspected 2

Contraindications and Precautions

• Should not be used in patients with:
  • Intestinal obstruction
  • Acute inflammatory bowel conditions
  • Severe abdominal pain of unknown origin
  • Rectal bleeding of unknown cause
  • Recent colorectal or gynecological surgery
  • Recent anal or rectal trauma 2, 5

Special Populations

• Cancer patients: Commonly used for opioid-induced constipation; may be part of a bowel regimen that includes oral stimulant laxatives 2
• Elderly: Can be used but start with lower doses and monitor for electrolyte disturbances 5
• Pregnant women: Use with caution and only when clearly needed 4

Practical Tips

• For best results, try to use after breakfast to work with the body's natural gastrocolic reflex
• Ensure privacy and comfort during defecation attempts
• Patient should be educated that some mild cramping may occur as the suppository takes effect
• If impaction is present, glycerine suppositories may be used first or manual disimpaction may be required before using stimulant suppositories 2

Common Pitfalls to Avoid

• Using suppositories as first-line therapy when oral options haven't been tried
• Prolonged use without addressing underlying causes of constipation
• Using in patients with contraindications (intestinal obstruction, acute inflammatory conditions)
• Failing to combine with appropriate oral therapy for chronic constipation
• Not addressing patient concerns about invasiveness, which can be a barrier to adherence 2, 4

Microlax and other bisacodyl suppositories represent an effective option for managing constipation, particularly when rapid relief is needed or when oral therapies have failed. They should be part of a comprehensive approach that includes appropriate lifestyle modifications and oral laxatives when necessary.