TUESDAY, Oct. 16 (HealthDay News) -- When taken once a day as an added therapy, the epilepsy drug lamotrigine is effective in controlling partial seizures, an international study finds.

The 239 participants, aged 13 and older, were recruited from the United States and several other countries. They were already taking one or two medications, but these did not fully control their partial seizures.

The patients received either lamotrigine in extended-release formula or a placebo for 19 weeks. They continued taking their other epilepsy medications.

Patients who had lamotrigine added to their therapy had 46 percent fewer seizures during the study, compared to 24 percent fewer seizures among patients taking the placebo. The study also found that 42 percent of the patients who took the drug had reduced seizure frequency by the end of the study, compared with 24 percent of those who took the placebo.

The study, published in the Oct. 16 issue of the journal Neurology, was sponsored and conducted by drug maker GlaxoSmithKline, which markets lamotrigine as Lamictal.

"This new once daily medication may be an important option for people with epilepsy that could significantly increase their compliance with prescribed treatment," study author Dr. Dean Naritoku, of Southern Illinois University in Springfield, said in a prepared statement.

Patients need to take their medication reliably and consistently in order to maintain stable blood levels of epilepsy drugs and good control of seizures.

"The more often people have to remember to take their medication each day, the more likely they are to miss a dose. Once-a-day dosing is more convenient for patients," Naritoku said.

More information

The Epilepsy Foundation has more about epilepsy medications.