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Generic Substitution and Interchangeability

Medications and key message of DO NOT SUBSITUTE

It is very important that people with epilepsy and their families are aware of Generic Substitution & Interchangeability. This section provides information on the practice of Generic Substitution; why it is in place; and what people with epilepsy can do to ensure that they receive a consistent version of their medication.

What is Interchangeability/Generic Substitution?

When a medication is deemed Interchangeable, it means that pharmacists can dispense a generic version of a particular medicine, even when a specific brand is prescribed.

What is a branded medication?

A branded drug (also called an originator or innovator drug) is a drug that has a trade name or has been protected by a patent in the recent past. It can be produced and sold only by the company holding the patent.

What is a generic medication?

A generic medicine is one that is like the original, brand-name medicine, and contains the same active substances but it will have a different (but often similar) name. Generic versions of branded drugs can be made by any other drug company once the patent on the branded drug expires. Generic versions of a medicine may have different colours, flavours or non-active substances. They may also be a different shape or size and come in different packaging.

Why is generic substitution a practice?

The price of generic medication is usually less than the branded drug as the company making the generic version does not have to cover the costs of research and marketing that were involved in developing the original drug. Therefore, the aim of the legislation allowing for generic substitution/interchangeability is to reduce the costs of medications on the state. For other conditions, the practice of generic substitution is not usually an issue. However, there are concerns around this practice from an epilepsy perspective.

What are the concerns around Interchangeability/Generic Substitution for people with epilepsy?

There are no particular concerns that generic versions are less effective as branded drugs in controlling seizures in an individual person with epilepsy when prescribed from the beginning of treatment.

However, there have been concerns and debates for many years about the safety of switching patients from a branded version of an epilepsy drug to a generic version or from one generic version to another. For interchangeable drugs, switching may occur regularly in some cases, depending on which version is the cheapest at the time of dispensing.

The specific safety concerns around epilepsy medications are because many of them have a "narrow therapeutic range". As most people with epilepsy will be only too aware, finding an effective dose can be difficult and time consuming. Once that is found, any variation in the manufacture and composition of a medicine, even when within the normal range permitted, introduces a new factor that may disturb the balance and result in an otherwise avoidable breakthrough seizure. This is the key concern around epilepsy medications being deemed interchangeable.  

Who decides whether a medication is interchangeable?

The decision to deem a medication interchangeable is made by the Health Products Regulatory Authority.

Are all epilepsy medications interchangeable?

No. Only three Anti-Epileptic drugs are interchangeable.

What epilepsy medications are currently interchangeable?Medications and key message of DO NOT SUBSTITUTE

Currently, three epilepsy medications have been deemed interchangeable. They are as follows:

How can I ensure that my prescribed medication is not substituted?

Crucially, there are steps you can take to ensure that you are given the same version of your medication each month. We advise that patients taking the above medications  follow the steps outlined below. We also encourage all people with epilepsy on any epilepsy medication to discuss generic substitution with their clinicians and to follow these steps if you are concerned about the risks of switching.

  1.  Ask your prescriber to use the BRAND name or a specific named generic version on your prescription rather than the generic name (i.e. write Keppra, not Levetiracetam).
  2. Ensure “DO NOT SUBSTITUTE” is written or printed on your prescription (for each epilepsy medication).
  3.  At your pharmacy, check your medications immediately to ensure that they are the same as the ones you received last month. If they are not, insist that they are changed back.

If you would like to discuss any of the above or have further questions, please do not hesitate to contact our team. Their details can be found by visiting the ‘Our Local Service’ section of our website.