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SAMPLE PRESCRIBING REPORT
LAXATIVE USE

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Are people on long term opiates being prescribed stimulant laxatives?

National picture

Long term opiate use frequently results in constipation and it is recommended that people on long term opiates also receive a stimulant laxative. This is because constipation almost always occurs (due to reduced gut motility) and tolerance to the effect does not occur. We decided to look at dispensings for people on opiates and see if they were also dispensed oral stimulant laxatives. Oral stimulant laxatives include bisacodyl, senna and docusate with senna (Laxsol). Docusate with senna is an ideal combination for people with opiate induced constipation. In addition to these, we included docusate (Coloxyl) on its own because although it is primarily a faecal softener it does have some stimulant activity.

Oral laxative use among patients dispensed opiate
analgesics 1 December 2006 - 31 May 2007*:

first...
Initially we examined the data for people who had been dispensed any opiate in the period 1 December 2006 to 31 May 2007 to see if they were also dispensed a stimulant laxative in that time period. Table one shows that 109,080 people received an opiate during this time period and only 14.3% received a stimulant laxative.
All patients dispensed an opiate Table One
Laxative Dispensed Number of Patients Percentage
None 85,886 78.7 %
Other (not stimulant) 7,558 6.9 %
Stimulant 15,636 14.3 %
Sum: 109,080  
All Opiates
 

next...
However, as many of these people may only have been on short term treatment, we narrowed the search to include people who had received four or more dispensings for an opiate during the six month period. Table two shows that of the 33,540 people who received four or more dispensings of an opiate, 26.6% also received a stimulant laxative.
4+ dispensings of an opiate Table Two
Laxative Dispensed Number of Patients Percentage
None 21,591 64.4 %
Other (not stimulant) 3,015 9.0 %
Stimulant 8,934 26.6 %
Sum: 33,540  
All Opiates
 

finally...
We then limited the search to include people who had received four or more dispensings for morphine, dihydrocodeine or oxycodone, as these medications are more likely to be used for chronic pain, such as for people receiving palliative care. Table three shows that of the 13,838 people dispensed these drugs, 42.5% received a stimulant laxative, 9.9% a non-stimulant laxative and 47.6% no laxative
4+ dispensings of opiates more likely
to be used for chronic pain		 Table Three
Laxative Dispensed Number of Patients Percentage
None 6,581 47.6 %
Other (not stimulant) 1,369 9.9 %
Stimulant 5,888 42.5 %
Sum: 13,838  
Morphine sulphate
Dihydrocodeine tartrate
Oxycodone hydrochloride

This data shows there is room for movement and serves as a reminder to consider prescribing a stimulant laxative for people on long term opiate medication.

Multiple laxative use and drugs that can cause constipation

A number of drugs can cause or exacerbate constipation. We thought it would be interesting to look at how many people taking laxative(s) were on drugs likely to exacerbate or cause constipation.

The drugs that we considered could be causing or exacerbating constipation are listed below. It is by no means a complete list:

  • Tricyclic antidepressants
  • Anticholinergics
  • Prochlorperazine
  • Methotrimeprazine
  • Haloperidol
  • Oxybutynin
  • Chlorpromazine
  • Opiates

There are four classes of laxatives described in the PHARMAC schedule: bulk-forming agents, faecal softeners, osmotic laxatives and stimulant laxatives. We divided the people who had been prescribed a laxative in the time period into those who had been prescribed laxatives from one, two, three or all four of these classes. For these groups we then looked to see what percentage were on a drug which can cause constipation.

National picture

Figure one shows that the more classes of laxative people are prescribed the more likely they are to be taking one of the drugs that are likely to be causing or exacerbating the constipation.

 Figure One: National patients on laxatives*

A GP’s prescribing

It is indicative only, intended to reinforce our message of checking for drugs that cause constipation before prescribing additional laxatives. Patients were assigned to a GP if they were dispensed at least one laxative on a prescription with their NZMC number. Other laxatives or the drug(s) which can cause constipation may have been supplied by other prescribers.

  % of patients NOT on constipation causing drugs
  % of patients ON constipation causing drugs
Figure Two: A GP's patients on laxatives*

The take home message is that if you are considering adding a second laxative to a patient’s treatment regimen it is worth checking if they are on a medication that might be causing the problem. You may be able to modify the dose or find an alternative.

*Notes to Data:
Time period is 1 December 2006 to 31 May 2007.
Laxatives include oral presentations only.
Data has been excluded where the NZMC number or NHI number was not recorded.
For the purposes of this report, ‘Stimulant Laxative’ is defined as follows:

Docusate sodium Bisacodyl
Docusate sodium with sennosides Senna
The four classes of laxatives are
(1) Bulk-forming Agents; (2) Faecal Softeners;
(3) Osmotic Laxatives; (4) Stimulant Laxatives.