MHRA drug safety advice: Risk of serious and fatal overdose with fentanyl patches

The September 2008 edition of ‘Drug Safety Update’ from the MHRA contains advice on the risk of overdose with fentanyl patches, following spontaneous reports from healthcare professionals, patients, and carers, of unintentional overdose due to dosing errors, accidental exposure, and exposure of the patch to a heat source.  

Factors identified as possibly related to unintentional overdose include dosing errors (by healthcare professionals, patients, or caregivers); accidental exposure (particularly in children); and exposure of the patch to a heat source, possibly resulting in increased fentanyl absorption. These reports also provide some evidence of inappropriate prescribing of fentanyl patches, including prescribing in unlicensed indications and in opioid-naïve patients.

The MHRA has issued the following advice for healthcare professionals (taken directly from the article):

• Healthcare professionals, particularly those who prescribe and dispense fentanyl patches, must fully inform patients and caregivers about directions for safe use:
• follow the prescribed dose
• follow the correct frequency of patch application
• ensure that old patches are removed before applying a new one
• patches must not be cut
• avoid touching the adhesive side of patches and wash hands after application
• follow instructions for safe storage and disposal of used or un-needed patches
• Increased body temperature, exposure of patches to external heat sources, and concomitant use of CYP3A4 inhibitors may lead to potentially dangerous rises in serum fentanyl levels. Concomitant use of other CNS depressants might also potentiate adverse effects from fentanyl

Healthcare professionals, particularly those who prescribe and dispense fentanyl patches, should ensure that patients and caregivers are aware of the signs and symptoms of fentanyl overdose. Patients and caregivers should be advised to seek medical attention immediately if overdose is suspected Patients who experience serious adverse events should have the patches removed immediately and should be monitored for up to 24 hours after patch removal.

Drug Safety Update: Volume 2, Issue 2 September 2008 (link to abstract)