Male patients taking valproate have been urged to speak to their healthcare professional if they are planning to have children in the next year.

This comes as the UK medicines regulator considers new evidence suggesting that children whose fathers took valproate are at increased risk of neurodevelopmental disorders.

A new study, commissioned by the European Medicines Agency, found that around five in 100 children born to fathers treated taking valproate around conception were diagnosed with a disorder, compared with three in 100 children with fathers who took other antiseizure drugs.

The Medicines and Healthcare products Regulatory Agency (MHRA) confirmed yesterday that these results will be ‘rigorously analysed’, but in the meantime urged caution for male patients who want to have children.

‘As a precaution, male patients on valproate who are planning a family in the next year should talk to their healthcare professional about their treatment,’ the agency said.

In December, the MHRA warned healthcare organisations to prepare for new tightened rules on prescribing valproate which are due to come in later this month.

Under these rules, the epilepsy drug must not be started in new patients – male or female – under the age of 55 unless two specialists have agreed and documented that there are no other effective or tolerated treatments.

The study on child outcomes based on fathers who take valproate concluded that the paternal risk is ‘much smaller than the risk associated with valproate in pregnancy’.

It has been estimated that one in nine babies exposed to valproate during pregnancy will be born with a major birth defect, and as many as four in 10 with a neurodevelopmental disorder including autism.

In August, when the study on paternal risk was first submitted, the brand leader for valproate informed the MHRA of errors in the study which forced the researchers to conduct a full re-analysis.

After re-submission, the regulator confirmed it will review the results as part of its ‘ongoing monitoring of the safety of valproate’.

But this will not have ‘implications’ for the new strengthened safety rules coming in this month, according to the MHRA.

Any further guidance resulting from the study’s findings, based on the MHRA’s review and independent advice from the Commission on Human Medicines, will be communicated to healthcare professionals ‘as soon as possible’.

In June last year, NHS England launched a new tool to help with decisions on whether sodium valproate should be prescribed for epilepsy or bipolar disorder by weighing up the benefits and potential harms.

A version of this article first appeared on our sister title Pulse.