HSIB: Unintentional overdose of morphine sulfate oral solution (28 April 2022)

Summary

This Healthcare Safety Investigation Branch (HSIB) investigation aims to improve patient safety in relation to the use of oral morphine sulfate solution (a strong pain-relieving medication taken by mouth). As its ‘reference case’, the investigation used the case of Len, an 89 year-old man who took an accidental overdose of morphine sulfate oral liquid.

Patient Safety Learning has published a blog reflecting on the key patient safety issues highlighted in this report.

Content

Findings

• The initial choice of paracetamol and ibuprofen to control Len’s pain following his fall was in line with national guidance.
• Len’s pain was not effectively controlled on paracetamol and ibuprofen, therefore required review by his GP to address this.
• The choice of a morphine liquid was in line with national guidance and a reduced morphine dose was prescribed in line with recommendations for the older person and Len’s degree of kidney dysfunction.
• Len’s dose of morphine was displayed on the dispensing label attached to the outer box that the morphine was provided in. The label was not seen by Len or his Wife.
• Len and his Wife read the manufacturer’s text on the morphine bottle, which showed the strength of the morphine liquid, and understood this to be the required dose.
• When Len was taken to hospital with difficulty with breathing, he was found to have taken an accidental dose of morphine, he had a chest infection and his Charcot-Marie-Tooth disease may have impacted on his breathing.

Safety observations

HSIB made the following safety observations:

• It may be beneficial if manufacturers of morphine oral solution 10mg in 5ml ensure that any dose measurement aid, if supplied with the medication, is able to measure a full range of possible doses.
• It may be beneficial if professional bodies provided guidance and further support to their members to maximise the learning that can be achieved from safety investigations that may improve patient care.