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N.P. Poolos, C.E Castagna, S. Williams, A.B. Miller, T.J. Story. In Epilepsy & Behavior 2017; 69: 59-68.


A common question in epilepsy care is, “What dose of seizure medicine works best?” How well a drug works is determined first by changes in seizure control. Yet side effects of medicines can make a drug hard to take long term, even it if helps lower seizures. Research in people with new onset seizures has shown that low doses of a seizure medicine may work well in many people. Yet, for people with refractory epilepsy (uncontrolled seizures), higher doses are usually used. This study looked at the association of the dose of seizure medicine and long-term responses.

Description of Study

  • This study looked at information from 164 adults with refractory epilepsy and mild developmental disabilities. The adults were cared for at two state-run facilities in Washington.
  • For purposes of this study, refractory epilepsy meant that the adult had at least one seizure yearly despite at least 2 different trials with seizure medications.
  • Researchers looked at information from 1980 to 2015. The average length of follow-up information for each person was 17 years.
  • Information collected included: seizure frequency and type, most frequently used seizure medications, and dosages of each medicine used. 
  • Each person had tried an average of 6 trials of seizure medicines. The average seizure frequency was 2.8 seizures each month.
  • The responses of people to the 12 most frequently used seizure medicines were examined. The medicines may have been given alone or in combination with another seizure medicine. 

Summary of Study Findings 

  • The 4 most frequently used medicines and one combination of medicines were looked at for daily doses and seizure control. These medicines included:
  • People who were treated with the combination of lamotrigine and valproate had a significant improvement in seizures compared to their baseline and other seizure medicines. This response was best in people with focal epilepsy but also had a positive response in people with generalized epilepsy. 
  • When seizure medicines were given alone (just one medicine at a time), people who took a dose at the lower range seemed to have the best response compared to their own baseline seizure frequency.

What does this mean? 

  • Prescribing seizure medicines is a difficult process and needs to be individualized for each person. What one person responds to may be different than another person. 
  • This study was retrospective, which means it looked at a group of information that was collected in the past.  
  • The data was analyzed to look at trends and how people responded over time to seizure medicines. It did not include data on individualized patient issues that may have contributed to treatment decisions. 
  • The finding that many people responded best to the four most common seizure medicines when used at low doses offers a different view of using these medicines in people with refractory epilepsy and developmental disabilities. 
  • The most frequently used medicines during the study period included 3 older seizure medicines (carbamazepine, valproate, and phenytoin). This study does not tell us about doses of the newer seizure medicines except lamotrigine. 

People with epilepsy and their families can use this information to help them ask their care providers about their own seizure medicines and how to track their responses. It’s critical to remember that everyone is different and the type and dose of medicine prescribed for each individual will depend on a number of factors.

Article published in Epilepsy & Behavior, April 2017.

Authored By: 
Patty Obsorne Shafer RN, MN
Authored Date: 
Reviewed By: 
Joseph I. Sirven MD
Tuesday, May 16, 2017