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Posted 4 Mar 2015 in Medication

Opioids are a class of medicines (which include morphine, oxycodone, methadone, and fentanyl) that are very effective in managing severe pain.

Being a high-risk medicines indicates that special care is required when the medicine is prescribed, dispensed, supplied, stored and administered. They are also the class of medicines most commonly implicated in patient harm. The extent of this harm has been demonstrated internationally and locally and is the reason opioids have been at the top of high-risk medicines list since 1989.

Harm can include potentially life-threatening over-sedation and respiratory depression (leading to respiratory arrest if not recognised and corrected). Other common adverse effects associated with prescribed opioid therapy include nausea, vomiting, constipation, delirium, hallucinations, falls, hypotension, aspiration pneumonia, and addiction.

Opioids were the number one medication class causing harm when measured in the New Zealand Quality of Healthcare study[1] and more recently in a study in three district health boards (DHBs)[2]. In both studies just over 17 percent of adverse events were caused by opioid use in hospitals.

Of the 132 medication-related serious adverse events reported to the Commission between July 2007 and June 2013, 23 related to opioids (17.4 percent)[3]. A similar picture is seen internationally.

In England and Wales, opioids were responsible for 52 percent of medication-related deaths and 62 percent of severe harms reported to the National Reporting and Learning System. A United States hospital reporting system also identified opioids as the number one cause of harms, 21 percent were due to prescribing errors, and 52 percent of these resulted in overdose.

Opioids are also one of the most commonly prescribed medicines in hospitals with studies showing up to 50 percent of patients are prescribed them at some stage during their admission.

Opioids have particular characteristics that exacerbate their high-risk:

  • many look-alike or sound-alike names and packaging– which can lead to errors in prescribing, dispensing and administration
  • multiple different routes of administration with different potency depending on the route which can lead to errors
  • patients starting on opioids need to be closely monitored for signs of respiratory depression and sedation
  • errors with opioid prescribing/dispensing/administration can cause respiratory depression
  • there are physiological factors that affect the way opioids are handled by patients
  • they interact with other sedating medicines.

The Commission is partnering with DHBs in a national safe use of opioid collaborative from October 2014–April 2016. The goal of the collaborative is to reduce harm from opioids in DHB hospitals and build capability in medication safety and quality improvement.

The Commission has also developed an Atlas of Healthcare Variation domain for opioids. This domain gives clinicians, patients and providers an overview on the use of opioids, grouped into strong and weak, and also morphine and oxycodone separately, by DHB. It uses community dispensing data.

March is the final month of the high-risk medicines topic and will focus on the safe use of opioids. A factsheet and poster on opioids will be released. DHBs are encouraged to promote the work that their collaborative members are doing. Margaret Pye shares her experience of side-effects from morphine.

On 24 March 2015 a webinar will be held on how the Atlas can be used to identify areas of wide variation and potential areas for quality improvement in community and secondary use of opioids.



  1. Bates DW, Cullen DJ, Laird N et al. Incidence of adverse drug events and potential adverse drug events: implications for prevention. JAMA 1995; 274:29–34.
  2. Seddon, ME, Jackson A, Cameron C et al. The Adverse Drug Event Collaborative: a joint venture to measure medication-related patient harm. NZMJ 25 January 2013, Vol 126..
  3. Health Quality & Safety Commission Reportable Events