Medications, epilepsy and climate change: the need for action

As we continue to experience increasingly hot summers, researchers warn that commonly prescribed anti-seizure medications could be affected by the heat. And they are calling for further studies to better understand what measures could be taken to prevent medications degrading.

Medications, epilepsy and climate change: Added Layers of complexity, is a review co-authored by Professor Sanjay Sisodiya, Transformation Director at the Epilepsy Society. Published in the British Journal of Clinical Pharmacology it explores the impact of climate change on the quality of life for people with epilepsy. 

Epilepsy affects around 50 million people worldwide of all ages although there are twice as many people with the condition in low-income countries compared to high-income countries. The review explores the potential effects of climate change on anti-seizure medications, antipsychotics and antidepressants and how it could affect people across the globe. 

Commonly prescribed anti-seizure medications including carbamazepine, valproate, phenytoin or lorazepam appear to be at risk of being affected by high temperature and/or humidity.  When medication tends to be stored in the kitchen, bathroom, living room or bedroom, it is more likely to be affected by changes to humidity and temperature. It is recommended that further studies are needed to simulate current adverse weather events to understand what measures could be taken to prevent the drugs degrading in the heat. 

Additionally, people with epilepsy may have adverse reactions to their medication due to heatwaves and could develop heatstroke. The adverse effects of anti-seizure medications (ASMs) associated with hyperthermia, where the body temperature rises above the normal range,  may be particularly important in people with temperature-sensitive seizures, such as those seen in Dravet syndrome. 

Some medication needs to be stored at a particular temperature so keeping it in a kitchen, bathroom or garage is probably inappropriate. As the weather gets above 25 °C during hot days it’s important that patients, pharmacists and primary care physicians are aware of this and take steps to make sure the drugs are stored in the right conditions. Even transporting medication in the boot of a car to use in an emergency could make the drugs less affective. 

The paper also highlights the interesting and potentially important issue ofthe impact of climatic factors on the stability of ASM and their metabolites in blood samples collected from the PWE for therapeutic drug monitoring (TDM). We have a TDM here at the Epilepsy Society and will be sharing this information with our colleagues. 

Climate anxiety may also affect any individuals with epilepsy. Depression, anxiety, bipolar disorder, schizophrenia and diseases such as dementia or Alzheimer’s disease are common associated conditions of epilepsy. Cognitive impairment, which is common in people with epilepsy, has been identified as a risk factor for heat-related illness in adverse weather events. 

Sodium valproate, carbamazepine or phenobarbital are the most prescribed ASMs in Nigeria, Pakistan and South Africa and these first generation ASMs appear to be most vulnerable when exposed to extreme temperatures and/or humidity. 

While the consequences of these effects have not been widely studied, it also raises concerns that the relationship between extreme temperatures and seizure control leads to more frequent seizures. 

The paper concludes that the growing impact of climate change means that it is crucial to conduct further research to understand how fluctuations in temperature and humidity could consequently alter the effectiveness of various drugs. 

Practical tips that may address the impacts of climate change on drug response include: 

• Incorporating monitoring of response to ASMs into clinical trials during heatwaves
• Advice on safer storage on medications during extreme temperatures
• Developing clear guidelines for healthcare professionals on how adverse weather events might affect drug responses in people with epilepsy. 

The study concludes that while climate change presents a fundamental threat to our health and poses an additional challenge for people with epilepsy, it may be relatively easily addressed.

You can read the paper here and find out more about our climate change research at: Epilepsy Climate Change (EPICC) | Epilepsy Society