What is known

A systematic review of studies of lactulose (osmotic agent) as an aperient in a range of populations, including those with terminal illness, showed that lactulose was better than placebo for managing constipation. However in some studies the difference was small. [1]

A systematic review of docusate (softener) in palliative care patients based on small studies which were not of good quality, showed a small trend to increased stool frequency with the use of docusate. The conclusion was that good quality studies are needed to demonstrate the value of this treatment in a palliative care population. [2]

A prospective open label volunteer study assessing the role of combinations of laxatives in the management of opioid induced constipation provides support for the recommendation to use a stimulant and a lubricant or softening laxative together as prophylaxis when prescribing opioids. [3]

There are small studies of sodium picosulphate (stimulant) [4] and polyethylene glycol (macrogol) (osmotic agent) [5] in a palliative care population which show promise. Polyethylene glycol has been used in the management of faecal impaction, and appears to be effective [6-7] although these studies were not focused on palliative care patients.

The recently released medication, methylnaltrexone, is an opioid antagonist specifically developed for treating opioid induced bowel dysfunction, which can be given subcutaneously. A recent systematic review concluded that it shows promise, but further evidence of safety and efficacy are still needed, and it is likely to be reserved for second or third line treatment. [8]

What it means in practice

• Prescribing of laxatives continues to be based on expert opinion. The principles of prescribing laxatives in a palliative care population focus on prevention of constipation. Co-prescription of either a stimulant (senna is commonly used in Australia) plus a softening or lubricant laxative such as docusate (eg Coloxyl), or increasingly, of macrogol (Movicol), are commonly suggested as best practice for patients on opioids. [6-7, 9]
• Expert opinion is that fibre and bulk-forming laxatives are associated with problems in palliative care patients, especially if oral intake is reduced. [9]
• Educating patients about the relationship of constipation to opioids, and the need for laxative co-therapy, is also an essential part of opioid prescribing.
• Regular assessment for constipation, and of adverse effects of laxative therapy (pain, bloating, flatulence), is an essential part of ongoing care.
• Little is known of the individual variability of response to laxatives. [10] However it is reasonable to consider patients’ own preferences in the choice of laxative.

Finding out more

Guidelines 

• The management of constipation in palliative care: clinical practice recommendations. Larkin PJ, Sykes NP, Centeno C, Ellershaw JE, Elsner F, Eugene B, et al. Palliat Med. 2008 Oct;22(7):796-807.

Link to prescribing information

• Online Palliative Medicine Handbook 
  Click on “Notes on Prescribing”
  This prescribing information is from the UK and some medications may not be available in Australia
• Therapeutic Guidelines for Palliative Care
  An Australian source of prescribing information not available directly online through CareSearch, but can be accessed online in most hospitals, or purchased.

Overview articles

• ABC of palliative care: constipation and diarrhoea. Fallon M, O’Neill B. BMJ. 1997 Nov 15;315(7118):1293-6.
• The Hand that Writes the Opioid… Woelk C. Can Fam Physician. 2007 June;53(6):1015-7.

Related CareSearch pages

Opioids
Bowel obstruction
Constipation

Previous          

References

1. Kot TV, Pettit-Young NA. Lactulose in the management of constipation: a current review. Ann Pharmacother. 1992 Oct;26(10):1277-82. 
2. Hurdon V, Viola R, Schroder C. How useful is docusate in patients at risk for constipation? A systematic review of the evidence in the chronically ill. J Pain Symptom Manage. 2000 Feb;19(2):130-6. 
3. Sykes NP. A volunteer model for the comparison of laxatives in opioid-related constipation. J Pain Symptom Manage. 1996 Jun;11(6):363-9.
4. Twycross RG, McNamara P, Schuijt C, Kamm MA, Jordan C. Sodium picosulfate in opioid-induced constipation: results of an open-label, prospective, dose-ranging study. Palliat Med. 2006 Jun;20(4):419-23. 
5. Wirz S, Klaschcik E. Management of constipation in palliative care patients undergoing opioid therapy: is polyethylene glycol an option? Am J Hosp Palliat Care. 2005 Sep-Oct;22(5):375-81.  
6. Culbert P, Gillett H, Ferguson A. Highly effective oral therapy (polyethylene glycol/electrolyte solution) for faecal impaction and severe constipation. Clin Drug Investig. 1998 Nov 1;16(5):355-60. 
7. Ungar A. Movicol in treatment of constipation and faecal impaction. Hosp Med. 2000 Jan;61(1):37-40. 
8. McNicol ED , Boyce D, Schumann R, Car DB. Mu-opioid antagonists for opioid induced bowel dysfunction. Cochrane Database Syst Rev. 2008 Apr 16;(2):CD006332.
9. Palliative Care Expert Group. Therapeutic Guidelines: Palliative Care. Melbourne: Therapeutic Guidelines Limited; 2005. 
10. Davis MP. Cancer constipation: are opioids really the culprit? Support Care Cancer. 2008 May;16(5):427-9. Epub 2008 Jan 15. No Abstract Available.

Last updated 05 July 2010