Campaigners are warning that switching the drugs of patients with epilepsy could lead to an increase of seizures.
Brainwave - the Irish epilepsy association - is calling on the Government to exclude anti-epileptic drugs from the Health Bill 2012 which would allow for a generic, or unbranded, drug to be substituted for branded drugs.
Brainwave has said that, due to the nature of epilepsy, any tiny variation in the composition of a tablet could have significant negative side effects.
A breakthrough seizure can increase the risk of physical injury, and even death.
There are almost 37,000 people in Ireland with epilepsy.