1.6 Laxatives

General Notes
For uncomplicated constipation, first–line therapy should be dietary manipulation with increased fibre and fluid intake.
(a) faecal loading of rectum

First Choice:
sodium citrate enema
(Micralax Micro–enema®/
Micolette Micro–enema®)
Second Choice:
phosphate enema
(Fletchers’ Phosphate Enema®)
Formulations/Dose
  • Micralax Micro-enema® one enema (5mL).
  • Micolette Micro-enema® 1–2 enemas (5–10mL).
  • Fletchers’ Phosphate Enema® one enema as required.
Prescribing Notes
  • Some patients may require manual disimpaction.
(b) new onset constipation

First Choice:
senna
Second Choice:
glycerol (glycerin)
orbisacodyl
Formulations/Dose
  • senna tablets 7.5mg; syrup 7.5mg/5mL: 2–4 tablets or 10–20mL syrup at night.
  • glycerol suppositories 4g: 4g suppository, moistened with water before use, as required.
  • bisacodyl suppositories 10mg: 10mg suppository in the morning.

Older Patients – Laxatives

Stimulant laxatives must not be used in the presence of faecal impaction.  Lactulose is not recommended for long-term use in older patients.
(c) Chronic constipation

First Choice:
ispaghula husk
Second Choice:
macrogol oral powder '3350'
Formulations/Dose
  • ispaghula husk 3.5g (Fybogel®) sachets: 1 sachet in water twice daily preferably after meals.
  • macrogol oral powder '3350' : initially, 1-3 sachets daily in divided doses usually for up to 2 weeks; maintenance, 1-2 sachets daily.
Prescribing Notes
  • Ispaghula may take several days to act.
  • Stimulant laxatives become less effective with long-term use.
  • If rectum is full on examination or there is difficulty in evacuation, consider glycerol or bisacodyl suppositories.
  • There are several different brands of macrogol 3350 oral powder available.  The most cost effective brand should be used.  There are no clinical differences between the brands. 
(d) other drugs used in constipation
Prescribing Notes
  • Linaclotide is approved for symptomatic treatment of moderate to severe irritable bowel syndrome with constipation (IBS-C).  It should be initiated on specialist advice only.  It is restricted for use in patients who have not adequately responded to or cannot tolerate all other suitable treatment options.

  • Naloxegol is indicated for the treatment of opioid induced constipation in adult patients who have had an inadequate response to laxatives. It should be initiated on specialist advice only. The recommended dose of Moventig® is 25mg once daily. When naloxegol therapy is initiated, it is recommended that all currently used maintenance laxative therapy should be halted, until clinical effect of naloxegol is determined.