For epilepsy patients, switching to a different antiepileptic drug (AED) is a common occurrence. The reasons vary; some patients experience only partial seizure control with a given AED, while others find side effects intolerable or worry about long-term consequences of drugs known to cause problems after decades of use.
A team of researchers at Thomas Jefferson University in Philadelphia followed patients who were taking phenytoin or carbamazepine alone as monotherapy for focal epilepsy and were switched to a different AED. The researchers matched each of 43 patients in the “switching” arm to 2 controls of the same seizure status who remained on anticonvulsant monotherapy. The researchers then monitored the participants’ seizure activity for 6 months.
The results, published in the January 2013 edition of Epilepsia, indicated that most patients who were seizure-free remained so after switching to a new AED; just one-sixth had seizures. However, patients who were seizure-free before the switch (ie, those who switched due to side effects or possible long-term consequences) were 6.5 times more likely to experience seizure recurrence than seizure-free patients in the control group, who did not switch medications.
Patients who initially were not seizure-free, however, had the same odds of seizure freedom if they remained on the same drug as they did if they switched. Seizure remission was more likely (but not significantly so) when patients remained on the same drug. Regardless of their pre-switch seizure status, patients who switched from older AEDs to newer agents with different mechanisms of action were no more likely to be seizure-free.
Based on their findings, the authors concluded that most improvements in drug-resistant patients who have focal epilepsy are probably spontaneous remissions rather than responses to new AEDs.
Ms. Wick is a visiting professor at the University of Connecticut School of Pharmacy and a freelance writer from Virginia.