Naltrexone/bupropion (Mysimba▼): risk of adverse reactions that could affect ability to drive

Advise patients that naltrexone/bupropion has been associated with adverse reactions such as dizziness or somnolence, which can affect ability to drive, operate machinery, or perform dangerous tasks. Advise patients not to drive if they suspect their ability may be impaired.

Advice for healthcare professionals:

  • people taking naltrexone/bupropion may commonly experience dizziness or somnolence, and may rarely experience loss of consciousness or seizure
  • these effects would pose a risk to their ability to drive or operate machinery especially at the beginning of the treatment or during the dose titration phase
  • advise patients experiencing adverse reactions with naltrexone/bupropion to not drive or operate machinery until they have resolved

Advice for healthcare professionals to give to patients about any medicine that may impair driving:

  • always check the leaflet that comes with your medicine for information on how your medicine may affect your driving ability
  • it is against the law to drive if your driving ability is impaired by any medicine
  • do not drive if you have side effects that may impair driving, such as difficulties with vision or concentration; feeling sleepy, dizzy, or faint; or seizures (fits)
  • do not drive, operate machinery, or perform dangerous activities while taking a medicine until you know how it affects you (especially just after starting or changing the dose of the medicine)
  • talk to your doctor or pharmacist if you have concerns about side effects while taking a medicine; side effects can be reported to the Yellow Card Scheme

Enhanced driving warning

Naltrexone/bupropion (Mysimba▼) is authorised in conjunction with diet and exercise for the management of weight in obese adults and in overweight adults with 1 or more weight-related conditions. At the time of publication, use of Mysimba in the UK is low and it is normally available only on private prescription.

An EU review of cumulative data has identified somnolence as a common risk with naltrexone/bupropion and loss of consciousness as a rare risk. Given these and other adverse reactions, a new warning has been added to the product information that naltrexone/bupropion may affect the ability to drive, operate machinery, or perform dangerous tasks.

In a few cases, loss of consciousness occurred when the patient was driving, including a small number of cases worldwide associated with a road traffic accident. As of publication of this article, no adverse drug reaction reports for naltrexone/bupropion received through the UK Yellow Card Scheme have indicated a road traffic accident was associated with the reported event.

Patients should be advised not to drive, operate machinery, or perform dangerous activities while taking naltrexone/bupropion until they know how the medicine affects them. This should be considered especially just after starting or changing the dose of the medicine.

Reminder: medicines and driving

It is against the law for a person in the UK to drive if their driving ability is impaired by any medicine. Please continue to discuss with patients any potential driving impairment associated with medicines you have prescribed and dispensed. The advice provided about driving in the Patient Information Leaflet for all medicines can form the basis for this discussion. Advice for healthcare professionals about the influence of a medicine on driving ability is also provided in section 4.7 of the Summary of Product Characteristics for all medicines.

Healthcare professionals may wish to consult the DVLA’s guidance for assessing a patient’s fitness to drive, if the patient experiences an adverse reaction that may affect their driving ability, for example if a recent loss of consciousness or seizure is suspected.

In England and Wales, it is also illegal to drive with blood concentrations of certain controlled drugs above pre-specified limits. See Drug Safety Update from 2015 for more information.

Report suspected adverse drug reactions via the Yellow Card Scheme

Please continue to report any suspected adverse drug reaction via the Yellow Card Scheme. Remember only a suspicion is needed to report – if in doubt, please complete a Yellow Card.

Healthcare professionals, patients, and caregivers can report suspected side effects via the Yellow Card website or via the Yellow Card app. Download the app today via iTunes Yellow Card for iOS devices or via PlayStore Yellow Card for Android devices.

You can also use the app to access the latest safety information from the MHRA about medicines and medical devices on the Newsfeed. Search for medicines to see details of Yellow Card reports others have made. Medicines of interest can also be added to a Watch List to receive news and alerts about new side effects and safety advice as it emerges.

Article citation: Drug Safety Update volume 13, issue 1: August 2019: 2.

Published 19 August 2019