Getty ImagesMen taking sodium valproate are being warned to use contraception while on the medicine, because of a “potential small increased risk” of autism and other neurodevelopmental problems for any children conceived.
They should continue to do so – and cannot donate sperm – until three months after they have stopped taking the drug.
Sodium valproate, prescribed under brand names including Epilim, Belvo, Convulex and Depakote, is an effective treatment for epilepsy and bipolar disorder.
The Medicines and Healthcare products Regulatory Agency (MHRA), which issued the warning, stressed patients must speak to their doctors before making any changes to their medicines.
‘Safety issue’
The guidance follows a similar warning from the European Medicines Agency, after data from national registries in Norway, Denmark and Sweden suggested 5% of children born to men taking the drug were harmed.
That study did not prove sodium valproate was the cause, the MHRA said, or compare risks for children whose fathers were not on medication.
But it raised an “important safety issue that warrants action on a precautionary basis”.
Sodium valproate was already known to make it more difficult to father a child.
But the MHRA says this is usually reversible after the drug is stopped.
Babies exposed to sodium valproate in the womb have a 40% risk of of autism and other neurodevelopmental problems and a 10% risk of physical abnormalities.
An estimated 20,000 children in the UK have had life-changing injuries from the medicine.
And in January, the MHRA warned under-55s should not take it unless all other treatment options had been rejected and its use had been signed off by two independent specialists.
Nevertheless, 65,000 children and adults under the age of 55 still take the sodium valproate.
MHRA chief safety officer Dr Alison Cave said: “Patients on valproate should not stop taking their medicine unless advised to do so by a healthcare professional.
“It is important to attend your next appointment in order to discuss your treatment plan.”