Could switching your epileptic medication to a generic actually cost you more?

Epilepsy is a common neurological disorder that affects more than 400,000 Australians and is estimated to affect 2% of people worldwide. Epilepsy is characterised by the continuing tendency for a person to have seizures. It is treated by a class of drugs called antiepileptic drugs (AEDs).

For a number of years there has been concern amongst doctors about the use of generic epileptic medication. For the majority of pharmaceuticals, generics present a safe and cheap alternative to the original medication. Yet in some cases, substituting a generic AED has been associated with increased incidences of breakthrough seizures and toxic side effects.

Professor Roy Beran is Associate Professor of Neurology at the University of New South Wales and Professor of Neurology at Griffith University, and is a neurologist specialising in epilepsy treatment. He said:

"If a person with epilepsy is stable on a product, then that is the product on which to stay."

Safety concerns are in many cases enough to nullify any cost benefits of generic AED substitution. With any switch in AEDs, whether it is brand to generic, generic to brand or generic to generic, there are potential implications that have associated costs. This includes direct costs such as doctor and pathology costs, as well as indirect costs such as breakthrough seizures leading to increased anxiety, seizures while driving resulting in road traffic accidents, toxicity, and absenteeism, to name a few. These potential costs of switching must be taken into consideration, as they could cause far greater financial concern than the expense of the branded drug, not to mention increased anxiety and decreased quality of life.

Prof Beran said, "I do not believe the cost benefit ratio justifies the risk associated with changing a patient’s antiepileptic medication."

That said, the underlying question is whether these safety concerns have been properly attributed to generic AEDs, when the issue is any switch between antiepileptic medication. Further research into this area is greatly needed to generate substantial practice guidelines.

Prof Beran said, "I think there is a risk going from a generic antiepileptic medication to a brand, as well as the other way round."

AEDs are a very unique and complicated strand of neuropharmaceuticals. There is only a very narrow range of doses that are therapeutic; therefore, toxic effects can result from increasing the dose slightly, and breakthrough seizures can occur if the dose decreases slightly. Somewhere in the therapeutic range is the critical dose, specific for the individual taking the medication, that achieves the optimum seizure control. This critical dose is found by titrating the dose over a number of appointments with a doctor, starting with a dose in the lower range and gradually increasing the dose until the optimal seizure control is achieved. One may be asked to keep a seizure diary in order to compare seizures across different AED doses.

It is the narrow therapeutic range that presents a problem for generic substitution. Even though the active ingredient in the generic drug is the same, a very small difference in biological effect caused by the inactive ingredients can alter the critical dose. Hence switching between AED brands can result in breakthrough seizures.

Research into this area has produced mixed results. A phenytoin formulation change in the 1960s lead to an outbreak in toxicity in people with epilepsy, and has since been changed back to the original formulation. A generic form of carbamazepine has been taken off the market after a number of people experienced breakthrough seizures. On the other hand, one recent study found no significant effects between the branded and original valproic acid in terms of seizures or blood levels.

Without further research and trials, it is simply impossible to determine the actual risk associated with generic AEDs or the switch from one form of drug to another. Until the unknown has been looked into further, it is wise to err on the side of caution.

Prof Beran said, "You should only switch medication if there is a lack of efficacy on your current medication.

"If this is the case, then you should only accept a generic antiepileptic prescription if it is a choice between getting nothing or getting a generic because of the cost factor."

The following are a reasonable set of precautions:

If you have been newly diagnosed with epilepsy, it is not uncommon or unreasonable for your neurologist to prescribe a generic medication, but this should be discussed with you first. As you have not had any AED before, you will not be switching from a brand to a generic drug.
If you are currently taking either a generic or branded medication and your epilepsy is not under control, your neurologist may first change the dose of your current AED. If there is still no improvement, they may then consider converting you to a different type of AED.
If you have your epilepsy under control and have done for some time, generic substitution is best avoided.

The importance of making sure you are educated in the medication you are taking should not be underestimated. In 1996, a study assessing attitudes towards medication in people with epilepsy found that while 74% reported they pay very close attention to their medication and would notice and query if it was different from the usual prescription, 19% said they would notice but would never query the pharmacist or doctor about the change, and an alarming 6.5% do not pay close enough attention to the drugs to be able to notice if they were given something different. This is approximately 26% of people with epilepsy admitting to not speaking up about, or not even noticing, changes in their medications.

Prof Beran said, "The reason we prescribe any medication for any disease is to improve quality of life. If this goal is achieved, there is no reason to change anything. If improved quality of life is not achieved, then the treatment options must be re-examined. Once your doctor has re-examined the variables, they may consider swapping to another medication."

References

NPS Media Release: Critical dose medicines and brand substitution: issues with anti-epileptic drugs [online]. National Prescribing Service. 6 February 2009 [cited 7 April 2009]. Available from URL: http://www.nps.org.au/ news_and_media_home/ media_releases/ repository/ Critical_dose_medicines_and_brand_substitution
ESA Position Statement: Generic drug use in epilepsy [online]. Epilepsy Society of Australia. 3 October 2008 [cited 7 April 2009]. Available from URL: http://www.epilepsy-society.org.au/ pages/ generic_AEDs.php
Treatment for epilepsy: Generic medications and substitution [online]. Epilepsy Australia [cited 7 April 2009]. Available from URL: http://www.epilepsyaustralia.net/ Epilepsy_Information/ Treatment_options/ Treatment_options.aspx#Generic
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