Switching brand and generic anti-seizure medicines for epilepsy

Reasons for switching

Many anti-seizure medicines (ASM) are available from multiple manufacturers resulting in a wide range of generic and branded products on the market. For some, there are more than one brand of the medicine as well as generic versions available.

Reasons to switch from one manufacturer’s product to another manufacturer’s product include:

• reduced costs
• availability of supplies
• individual preferences or intolerances

Risks when switching

Generic medicines must meet strict standards to match the original brand, but evidence on risks of switching between brands and generics is limited. Some very sensitive individuals with epilepsy may experience changes in seizure control or side effects after switching. This can be between a brand and its generic version or between two different manufacturers’ generic versions of the same ASM. The concern is greater with certain ASMs, particularly modified-release preparations.

Switching is not usually an issue when ASMs are used for non-epilepsy indications, such as neuropathic pain or mood disorders.

Only consider switching where there will be a significant clinical, logistical or financial benefit. Consider postponing a planned switch if the person is unwell or has an infection, until they have recovered.

Follow the advice below when determining whether to switch to a different manufacturer’s product to mitigate the risk of loss of seizure control.

Categories of ASMs according to risks when switching

The Commission on Human Medicines (CHM) classifies ASMs into 3 risk categories based on their characteristics: therapeutic index, solubility, and absorption. These risk categories help prescribers and people with epilepsy determine if continuity of a specific manufacturer’s product is needed.

Category 1: Avoid switching

Maintain on the same manufacturer’s product for the following:

• carbamazepine
• phenobarbital
• phenytoin
• primidone

There may be extenuating circumstances when it might be appropriate to consider switching a product, such as manufacturer shortages. See sections within this article called, ‘Points to consider before switching’ and ‘Dose availability and shortages’.

Category 2: Switch with caution

Use clinical judgement and consult the individual and/or their carer to determine whether there is a need to continue on a particular manufacturer’s product. Before switching there are points to consider to mitigate the risks of loss of seizure control and improve acceptance of another manufacturer’s product. See section within this article called ‘Points to consider before switching’.

• clobazam
• clonazepam
• eslicarbazepine
• lamotrigine
• oxcarbazepine
• perampanel
• retigabine
• rufinamide
• topiramate
• valproate
• zonisamide

Category 3: Switching usually acceptable

Switching is generally safe because the potential for clinically relevant differences to exist between different manufacturers’ products is extremely low. It is not necessary to ensure that people are maintained on a specific manufacturer’s product in this category. Assess individuals on a case-by-case basis as there are still points to consider before switching. See the section within this article called ‘Points to consider before switching’.

• brivaracetam
• ethosuximide
• gabapentin
• lacosamide
• levetiracetam
• pregabalin
• tiagabine
• vigabatrin

Points to consider before switching

Use our recommendations as part of an individual’s assessment to determine whether a switch will be safe and acceptable.

Dose availability and shortages

Avoid omitting doses. If the usual ASM is unavailable, it is better to give a different manufacturer’s product (of the same medicine) than to omit a dose. Any slight differences in bioavailability of different manufacturers’ products have a much lower risk of losing seizure control than missing a dose.

ASM shortages

Consult the SPS Medicines Supply Tool when there are shortages of ASMs to aid your decision.

Confirm medication history

Determine whether the person has previously experienced problems when switching between manufacturers’ products or if there is a known reason why they must not switch.

Check if non-seizure indication

Generic switching is generally safe for non-epilepsy conditions. Non-epilepsy uses of ASMs do not generally have significant consequences following minor changes in dose.

Check adherence

Check the person’s medication adherence. If they have poor adherence but tolerate missed doses without issue, they are less likely to be sensitive to the marginal differences when switching manufacturers.

This is an opportunity to explore reasons for poor adherence. Consider whether a different manufacturer’s product might improve it, such as one with different excipients, appearance, taste or size.

Shared decision making

Encourage people to be involved in their own healthcare, with clinicians guiding decisions made in partnership. Inform people taking ASMs of the benefits and risks of switching between different manufacturers’ products and ask for their views about switching.

Do not routinely switch people from existing ASMs without their consent unless urgent treatment is needed.

Individual perceptions

Consider individual perceptions of differences in product name, packaging, appearance and taste. These may cause dissatisfaction, anxiety, confusion, dosing errors and reduced adherence, particularly in people with living with autism, mental health problems or learning disabilities.

Check seizure control

Consider the individual’s current level of seizure control because this may influence a decision to switch to a different manufacturer’s product.

Good seizure control

Consider not switching people with optimal seizure control (seizure-free or seizure frequency has markedly reduced) to a different manufacturer’s product. This is particularly important where the recurrence of a seizure could lead to harm, for example, the loss of a driving license.

Unpredictable seizure control

Consider staying on the usual ASM brand or usual generic product for people with unpredictable seizure control. This reduces the number of variables affecting treatment. Consistency helps optimise treatment, especially for sensitive individuals.

Recent loss of control

Consider whether loss of seizure control might be an opportunity to switch to a different manufacturer’s product. Switching may be considered, particularly when additional or alternative ASMs are required. This can be done even if switching products is generally not recommended, for example, category 1 ASMs.

Modified-release formulations

Consider the additional risks of switching modified-release ASMs to other brands or generic products due to differences in release profiles and higher risk of variability.

Ketogenic diets

Do not switch people on a ketogenic diet to other brands or generics unless approved by their healthcare team. Different manufacturers’ products may have different carbohydrate content.

Excipients of concern

Consider the differences in excipients between different manufacturers’ products. Some manufacturers’ products may have excipients unsuitable for people with hypersensitivities, intolerances, religious and cultural beliefs or specific dietary requirements. This includes the alcohol content in some liquids for children.

Seek advice

If switching to different brands or generic ASMs and you require further advice on managing the switch, consult a specialist or your medicines information service. Primary care healthcare professionals can contact the SPS Medicines Advice service

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