New potassium-channel drug cut focal seizures in a phase 3 epilepsy trial

A new antiseizure drug that works by opening a potassium channel in nerve cells reduced focal seizures more than placebo in a phase 3 randomised trial, according to results published in JAMA Neurology [s1]. The drug, azetukalner, is not approved, and the finding rests on a single 12-week study — but the size of the effect is notable in a group of patients who had already run out of options.

The problem the trial is trying to solve

Despite more than 30 approved antiseizure medications, many people with focal epilepsy keep having seizures, which is why new mechanisms are still being sought [s1]. Azetukalner is described by the investigators as a potent opener of the KV7 potassium channel — a target that dampens the excitability of neurons [s1]. The participants here were not newly diagnosed patients with easy-to-treat epilepsy; they were people whose seizures had persisted through multiple drugs.

What the trial did

This was a phase 3, placebo-controlled randomised clinical trial run over a 12-week double-blind period, from 18 November 2022 to 3 February 2026, at 138 sites across North America, South America, Europe and the Asia Pacific region [s1]. It enrolled adults with focal epilepsy who were still having four or more focal seizures a month despite stable treatment with one to three antiseizure medications [s1].

Participants were randomised in equal thirds to placebo, 15 mg of azetukalner, or 25 mg of azetukalner, taken once daily with the evening meal for 12 weeks with no dose titration [s1]. The trial is registered as NCT05614063 [s2]. The main outcome was the median percentage change from baseline in monthly (28-day) focal seizure frequency [s1].

Of 607 adults screened, 374 were randomised and treated: 125 on placebo, 125 on 15 mg and 124 on 25 mg [s1]. Half were female (190, or 50.8%) and the mean age was 40.0 years [s1]. These were hard-to-treat patients: the median baseline frequency was 12.75 seizures a month, they had already tried and stopped a median of five antiseizure drugs, and most — 336 of them, or 89.8% — were taking two or three other antiseizure medications at the same time [s1].

What it found

Over the double-blind period, the median monthly seizure frequency fell by 10.4% in the placebo group [s1]. On azetukalner it fell further: by 34.5% on the 15 mg dose and by 53.2% on the 25 mg dose, each a statistically significant improvement over placebo [s1]. In other words, the higher dose roughly halved monthly seizures, and the drop on placebo — a real and well-recognised effect in epilepsy trials — accounts for only part of that.

The investigators describe the drug as generally well tolerated, with treatment-emergent side effects comparable to those seen in the earlier phase 2b study of the same drug [s1]. They characterise the 25 mg result as one of the largest median percentage reductions in seizure frequency versus placebo reported to date in drug-resistant epilepsy [s1].

How to read it

Two cautions keep this in proportion. First, this is one trial over a short window. A 12-week double-blind period captures whether a drug reduces seizures in the near term; it does not tell you how the benefit holds up over years, how the drug interacts with the many others these patients take, or how it compares head-to-head with existing options, none of which were tested here. Median percentage change is also a group statistic — it summarises the middle of a wide distribution, not a guaranteed result for any individual.

Second, azetukalner is investigational. A positive phase 3 trial is the kind of evidence that supports a regulatory filing, but it is not an approval, and the full safety picture — including rarer or longer-term effects — is assembled from more than a single study. The paper itself frames the drug as "promising" rather than proven in practice [s1].

What to watch

The near-term questions are regulatory and practical: whether this result, presumably alongside companion trials, is enough for approval, and what the label would say about dose and monitoring. The 25 mg dose delivered the larger effect, so how its tolerability compares with 15 mg in longer use will matter for how the drug is positioned. For now, the honest summary is that a new mechanism cleared a high bar in a demanding patient group, in a single well-run trial — a meaningful step, not a settled one [s1].

This article describes clinical-trial results and regulatory context and is not medical advice. Anyone with epilepsy should make treatment decisions with their neurologist, and should never start or stop an antiseizure medication on their own.