An investigational antiseizure medication, called XEN1101, may offer hope for patients with treatment-resistant epilepsy. A study that examined the efficacy and safety of the new drug revealed it may reduce seizures by more than 50% and in some cases, even eliminate them.

Researchers at NYU Grossman School of Medicine tested XEN1101 in a clinical trial involving 325 patients with focal onset seizures. The findings of the study were published in Jama Network.

The new drug when used with the participants' current antiseizure treatments showed a 33 to 53% drop in monthly seizures, depending on the dosage. It can be administered at its most effective dosage from the beginning, unlike other drugs that require gradual initiation with low doses, researchers claimed.

XEN1101 belongs to a class of chemicals called potassium-channel openers that function by boosting the flow of potassium out of nerves, effectively preventing them from firing. The drug, developed by Xenon Pharmaceuticals, is currently in phase 3 clinical trials and is not approved for use in the U.S. outside of a clinical trial.

"Our findings show that XEN1101 may offer a swift, safe, and effective way to treat focal epilepsy. These promising results offer hope for those who have struggled for decades to get their symptoms under control," Jacqueline A. French, a neurologist and the study's lead author, said in a news release.

Focal onset is the most common type of seizure seen in people with epilepsy, which begins in one side of the brain when nerve cells send out a sudden, excessive burst of electrical signals.

Antiseizure medications are an important part of epilepsy treatment to control or reduce seizures. A person is considered to have drug-resistant epilepsy when they fail to stay seizure-free even after trials of two antiseizure medications.

The latest study included participants who had tried an average of six antiseizure drugs that failed to treat their focal seizures. All participants had at least four episodes of seizures a month despite their ongoing treatment.

During the trial, they were randomly given a daily oral capsule of XEN1101 (in doses of 10 milligrams, 20 milligrams or 25 milligrams) or an identical-looking placebo for eight weeks.

Those who took the placebo had an average of 18% fewer seizures, while the treatment group had a 33 to 53% drop in monthly seizures.

"Most patients then volunteered to extend the trial, with about 18% of those treated with the new drug remaining entirely seizure-free after six months, and about 11% having no seizures after a year or longer," the researchers said in the news release.

The team claims the drug was "well tolerated" and brought side effects such as dizziness, nausea, and fatigue, which are also associated with other antiseizure medications. Since the drug takes more than a week to break down, it will help to avoid dramatic spikes and dips and treatment can be started in full strength. The longer breakdown time can also be helpful when a dose is accidentally skipped or taken late.

"Our study highlights the importance of finding as many therapeutic options as possible for those who have seizures. Since everyone responds differently, treating epilepsy cannot be a one-size-fits-all approach," French said.

Researchers plan to expand the participant pool and test the drug for potential long-term issues in specific groups, including pregnant women. They also intend to explore the use of the drug in the treatment of other types of seizures.

Treatment-Resistant Epilepsy: Experimental Drug May Reduce Seizures By More Than 50%