laxatives in palliative care

Last reviewed 01/2018

Constipation is a common cause of distress. Prevention is better than waiting until treatment is needed.

Constipation should be anticipated in all patients taking opioids or anticholinergics (e.g. tricyclic antidepressants) and those who are either inactive or have a reduced fluid or dietary fibre intake.

Laxatives (1,2,3):

• should be prescribed on a regular basis as soon as weak or strong opioids are prescribed (except those with ileostomy or diarrhoea), with full explanation to the patient
• relatively high doses may be required - the laxative dose may need increasing as the dose of opioid is increased
  • study evidence however showed no relationship between opioid dose and optimum dose of sodium picosulphate (4)
• a combination of stimulant laxative with a softening/osmotic agent is a good first choice e.g. co-danthrusate (dantron 50mg, docusate 60mg) - starting dose 1-2 capsules or 5-10mls at bedtime or co-danthramer (dantron 25mg, polxamer '188' 200mg) - starting dose 2 capules or 10ml at bedtime. More details about classification of laxatives in table below:
  
  

  Stimulants	Softener	Combined stimulant and softener	Osmotic
  bisacodyl glycerin senna dantron sodium picosulphate	docusate poloxamer	co-danthrusate (dantron and docusate) co-danthramer (dantron and poloxamer)	lactulose phosphate sodium citrate movicol

• 25% of patient on laxatives may still need rectal measures at times
• many ill patients will not tolerate high fibre diet or bulk forming laxatives but the need for good fluid intake, exercise, fruit and fruit juice (especially prune juice) should be explained to the patient
• co-danthrusate and co-danthramer contain dantron which stains urine red (warn patient) and can also may cause perianal skin irritation, especially in incontinent patients. It may be prudent to avoid dantron containing products in patients who are faecally incontinent or have a colostomy
• in general lactulose alone is not effective for opioid induced constipation and should not be used in patients with inadequate fluid intake. Lactulose can cause flatulence and abdominal cramps
• movicol oral powder (macrogol '3350', sodium bicarbonate) - may be preferable to lactulose if additional softener is required. Each sachet is dissolved in 125 ml water and can be mixed with fruit squash. Up to 8 sachets a day may be used in faecal impaction
• patients can be encouraged to become expert at adjusting their own laxatives

Treatment of existing constipation:

Before prescribing laxatives for established constipation

• rule out bowel obstruction. If bowel obstruction is suspected then seek further advice
• consider underlying cause e.g. hypercalcaemia, drugs

In spinal cord compression

• if normal sphincter sensation and function is present, titrate laxatives as normal, avoid excessive softening
• if normal sphincter sensation and function is absent, bisacodyl or sodium acid phosphate (Carbalax) supositories should be prescribed, aiming for a planned bowel action every 2-3 days

Reference:

• (1) West Midlands Palliative Care Physicians (2003). Palliative care - guidelines for the use of drugs in symptom control.
• (2) West Midlands Palliative Care Physicians (2007). Palliative care - guidelines for the use of drugs in symptom control.
• (3) West Midlands Palliative Care Physicians (2012). Palliative care - guidelines for the use of drugs in symptom control.
• (4) Twcyross et el. Sodium picosulfate in opioid-induced constipation: results of an open-label, prospective, dose ranging study. Palliat Med 2006;20:419-23