New measures recommending the avoidance of all medicines containing topiramate during pregnancy have been published by the European Medicines Agency‘s Pharmacovigilance Risk Assessment Committee (PRAC).
While it is well known that topiramate can cause major congenital malformations and foetal growth restriction if used during pregnancy, recent data also suggest a potential increased risk of neurodevelopmental disorders after exposure in the womb.
Topiramate-containing medicines are used for the treatment of epilepsy and the prevention of migraine, with some EU countries also using the drug in a fixed-dose combination with phentermine for weight reduction.
For patients using topiramate for the treatment of epilepsy, the latest PRAC recommendations state that the drug should not be used during pregnancy unless there is no other suitable treatment available. This builds on existing advice that topiramate is contraindicated during pregnancy when used for the prevention of migraine or for weight management.
Additional recommendations involve the establishment of a pregnancy prevention programme. This means that healthcare professionals should ensure any woman or girl who is able to have children has been made fully aware of and has understood the risks of taking topiramate during pregnancy, as well as the measures that must be taken.
This includes taking a pregnancy test before starting treatment and the need to avoid becoming pregnant during topiramate treatment by using effective birth control for the treatment duration and for at least four weeks after its cessation.
Alternative treatment options should be considered and the need for topiramate treatment should be reassessed at least annually using a risk awareness form.
The product information for topiramate-containing medicines will be updated to further highlight the risks and the measures to be taken and a visible warning added to the outer packaging of the medicines.
In addition, patients and healthcare professionals in Europe will be provided with educational materials regarding the risks of using topiramate during pregnancy, and a patient card will be provided to the patient with each medicine package.
Similar patient safety measures were also introduced by NHS England earlier in 2023 for valproate use in epilepsy.
Topiramate and neurodevelopmental disorders
These recommendations from the PRAC were based on the findings from three recent observational studies. In the first, prenatal exposure to topiramate was associated with increased risk of neuro-developmental disorders. The second study showed prenatal topiramate was linked to a greater risk of attention deficit hyperactivity disorder.
The third demonstrated that topiramate use late in pregnancy was associated with twice the risk of neurodevelopmental diagnoses in children compared to unexposed pregnancies.
In its review, the PRAC confirmed the known increased risk of birth defects and reduced growth of the unborn child when mothers receive topiramate during pregnancy. It estimated that birth defects will occur in between four and nine out of every 100 children born to women who take the drug during pregnancy, compared with one to three out of every 100 children to women who do not take topiramate.
In further analysis, the PRAC estimates that 18 in every 100 children were smaller and weighed less than expected at birth to mothers taking topiramate compared to only five in every 100 children born to mothers without epilepsy and not taking anti-epileptic medication.
Also triggered by the first study outlined above, the UK’s Medicines and Healthcare products Regulatory Agency announced in July 2023 that it had started a safety review of topiramate in relation to the potential for neurodevelopmental disorders.
