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The Drug Safety Update is an NHS Evidence accredited provider
9th September 2008
The MHRA and CHM have published the September edition of Drug Safety Update. Included in this issue is important drug safety advice to reduce the risk of serious reactions or fatalities from overdose with fentanyl patches. The hot topic is the introduction of human papillomavirus immunisation which is being introduced in the UK this month. Healthcare professionals are reminded of the importance of reporting adverse effects to this and other vaccines.
Action
Drug Safety Update is an essential read for everyone whose professional practice involves medicines. It is published every month in electronic format only.
Fentanyl patches
The MHRA have received reports of unintentional overdose of fentanyl due to dosing errors, accidental exposure, and exposure of fentanyl patches to a heat source. There is also some evidence of inappropriate prescribing of fentanyl patches, including prescribing in unlicensed indications and in opioid-naïve patients.
Healthcare professionals, particularly those who prescribe and dispense fentanyl patches, must fully inform patients and caregivers about directions for safe use as detailed in their Summaries of Product Characteristics. Patients and caregivers should be made aware of the signs and symptoms of fentanyl overdose — i.e. trouble breathing or shallow breathing; tiredness; extreme sleepiness, or sedation; inability to think, walk, or talk normally; and feeling faint, dizzy, or confused. Patients and caregivers should be advised to seek medical attention immediately if overdose is suspected. If patients experience serious adverse effects, the patches should be removed immediately and patients monitored for up to 24 hours after patch removal.
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.
The UK NPSA has recently issued a Rapid Response Report on dosing errors with opioid medicines. The NPSA recommends that knowledge of previous opioid dose is essential for safe use of these products, and that when a dose increase is intended the calculated dose is safe for the patient.
Common brands of fentanyl patch include Durogesic DTrans, Durogesic, Matrifen▼, and Tilofyl.
* Examples of CYP3A4 inhibitors include: ketoconazole, itraconazole, clarithromycin, erythromycin, verapamil, diltiazem, and amiodarone.
# Examples of other CNS depressants include alcohol, other opioids, anxiolytics, hypnotics, general anaesthetics, antipsychotics, skeletal-muscle relaxants, and sedating antihistamines.
Human papillomavirus immunisation
Routine immunisation for human papillomavirus (HPV) for girls age 12–13 years is starting this month across the UK. There will also be a phased catch-up of girls up to age 18 years.
Drug Safety Update includes guidance from the MHRA for people involved in delivering this immunisation programme, and includes details of potential adverse effect. Any adverse reactions that are suspected to have been caused by any vaccine, including the HPV vaccine, should be reported via the yellow card scheme.
Stop Press articles
These include:
- Contamination of Viracept (nelfinavir) with a carcinogen led to a recall in June 2007. However, new information suggests that patients who were exposed to the contaminant are not likely to be at an increased risk of developing cancer compared with patients with HIV who were not exposed to the contaminant. Similarly, pregnant women who were exposed to contaminated batches are not thought to be at increased risk of having a baby with birth defects.
- Advice to health professionals for the prescribing of natalizumab (Tysabri▼) is reinforced following reports of two further cases of progressive multifocal leukoencephalopathy in patients with multiple sclerosis (MS). This follows two earlier cases (one of which had a fatal outcome) seen prior to licensing in MS patients receiving the drug in combination with interferon beta.
Natalizumab must be prescribed in strict compliance with the Summary of Product Characteristics and according to the Physician Information and Management Guidelines from the marketing authorisation holder.
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