Recent Advances in Therapies for Potassium Ion Channel Dysfunction in Autism

 

Ο ήλιος, η θάλασσα και το EpiphanyASD — οι καλύτερες συνθήκες για να ανοίξουν νέα κανάλια σκέψης!

A recent comment from Konstantinos prompted this update to my earlier posts on potassium channels. Progress is being made, particularly in Fragile X, but also potentially for a sub-group of idiopathic autism with a specific pattern in their EEG.

  

From the original channelASD hypothesis to drugs entering clinical trials

Back in 2015, I wrote about the possibility of classifying some forms of autism according to dysfunction in particular ion channels. I used the term channelASD, drawing attention to potassium (Kv), sodium (Nav) and calcium (Cav) channels.

At the time, this was largely a mechanism-driven hypothesis. We knew that ion channels regulate neuronal excitability, and genetic research was beginning to implicate ion-channel genes in neurodevelopmental disorders. The therapeutic question was whether correcting a specific channel abnormality might improve some of the symptoms associated with autism.

More than a decade later, there are some interesting developments.

Two different potassium-channel activators are now attracting attention. Azetukalner, a Kv7 potassium-channel opener developed by Xenon Pharmaceuticals, has reached late-stage clinical development for epilepsy, with a New Drug Application submitted to the FDA in September 2026. Meanwhile, Spinogenix has announced a new autism study of codabakalner (SPG601), which activates a different potassium-channel family, BK channels. A second BK-channel opener, KER-0193, is also heading into Phase 2 in Fragile X syndrome.

None of these drugs has been demonstrated yet to treat autism. Nevertheless, these developments suggest that the ion-channel hypothesis deserves another look.

 

1. Why potassium channels matter

Potassium channels help control the electrical activity of neurons. When a neuron becomes activated, the movement of potassium ions across its membrane helps regulate the duration of electrical signals and determines how readily the neuron can fire again.

Different potassium channels operate at different stages of neuronal activity.

•        Kv7 channels help stabilise the resting membrane potential and limit repetitive neuronal firing. Kv7 plays a role in sensory gating, which is very often disturbed in autism.

•        BK channels are activated by both intracellular calcium and membrane depolarisation, helping regulate action potentials and neurotransmitter release. BK channels may help regulate sensory filtering and habituation.

•        SK channels are activated by intracellular calcium and contribute to after-hyperpolarisation, influencing how frequently neurons fire. SK channels help regulate neuronal firing patterns and sensory-signal processing, making them plausible contributors to sensory-processing abnormalities in autism; however, their role is complex, and the evidence for a specific SK-channel mechanism in autism remains limited.

•        Kv3 channels help certain neurons fire at high frequencies with precise timing, which is important for synchronised neural activity. Kv3 channels are a promising target for investigating sensory hypersensitivity in autism

•        Slack (KNa) channels are sodium-activated potassium channels that are directly regulated by FMRP, the protein missing in Fragile X syndrome.

It is tempting to think of potassium-channel activation as a general way to calm an overactive brain. However, this is too simple. Different channels have different functions, and some forms of neurodevelopmental disorder involve channels that are overactive rather than underactive.

The therapeutic objective should therefore be to correct the relevant physiological abnormality, not simply to increase potassium-channel activity.

A useful review is Potassium channels and autism spectrum disorder: An overview (2021), which discusses several potassium-channel genes implicated in neurodevelopmental disorders.

Read the review

2. Azetukalner: Kv7 channel activation reaches the FDA

Our very active reader, Konstantinos, recently commented on my old channelASD article:

"Ancient post, but Xenon filed for FDA approval of azetukalner, a potassium channel opener. Epiphany is such a precious knowledge place :)"

Thank you, Konstantinos!

Azetukalner is a Kv7 channel opener developed by Xenon Pharmaceuticals. Positive Phase 3 results (X-TOLE2) in focal-onset seizures were announced in March 2026, and on 17 September 2026 the company announced submission of a New Drug Application to the FDA.

Kv7.2 and Kv7.3 channels, encoded by KCNQ2 and KCNQ3, contribute to the neuronal M-current. This current acts as an important brake on repetitive firing.

Enhancing Kv7 activity can reduce neuronal excitability, which is why this channel family has attracted considerable interest in epilepsy drug development.

The progress of azetukalner demonstrates that Kv7 modulation can be translated into a clinically advanced treatment strategy.

Xenon is running Phase 3 studies of azetukalner in major depressive disorder (X-NOVA2 and X-NOVA3) and in bipolar depression, with topline data from X-NOVA2 expected in the first half of 2027. Those trials will tell us a good deal about how a Kv7 opener behaves in a psychiatric population, including its tolerability, although they say nothing directly about autism.

Xenon's September 2026 announcement

 

An important complication: some KCNQ mutations increase channel activity

Genetic studies have identified individuals with KCNQ2 or KCNQ3 gain-of-function variants who have developmental delay, language impairment and autistic features.

Sands et al. (2019) described 11 people with KCNQ3 gain-of-function variants. All had developmental delay and autistic features, while five received a formal autism diagnosis.

A separate study of 15 individuals with KCNQ2 gain-of-function variants found autistic features in ten.

These findings are particularly interesting because they challenge the idea that opening potassium channels should always be beneficial. In these particular genetic disorders, the channel is already excessively active. Further activation might be counterproductive.

The clinical implications are not straightforward, because the relationship between channel activity and neuronal network function is complex. Nevertheless, these studies illustrate why a genetic diagnosis and, where possible, functional characterisation may be important when considering targeted treatment.

3. BK channels: from Fragile X mouse studies to a human autism trial

Another strand of my earlier writing concerned calcium-activated potassium channels, particularly BK and SK channels.

The BK channel, encoded by KCNMA1, is activated by intracellular calcium and membrane depolarisation. It contributes to the regulation of neuronal firing and synaptic function.

Fragile X syndrome is particularly relevant to this line of research because loss of FMRP affects the regulation of numerous synaptic proteins and ion channels.

Human genetic evidence for BK channels

The case for BK channels does not rest only on mouse models. In 2006, Laumonnier and colleagues reported a person with autism and intellectual disability in whom the KCNMA1 gene was physically disrupted by a chromosomal translocation. The gene showed haploinsufficiency and the resulting BK channel activity was reduced, but could be enhanced in vitro by a BK-channel opener.

This is a single case, and a loss of BK function in one individual is not the same as a shared defect in Fragile X. It does, however, give the BK hypothesis a human genetic foothold.

Laumonnier et al., 2006, American Journal of Psychiatry

FRAXA published a helpful overview of the BK story in April 2026.

FRAXA: Opening the Gate — BK channel modulation in Fragile X

 

Chlorzoxazone

In 2024, Ferraguto and colleagues published a study of chlorzoxazone in a mouse model of Fragile X syndrome.

Chlorzoxazone is an existing muscle relaxant that can activate BK channels, although it is not a selective BK-channel drug.

In the Fmr1-knockout mouse model, chlorzoxazone improved several experimental outcomes, including hyperactivity, acoustic hyper-responsiveness and social-interaction measures. The investigators also reported restoration of impaired BK currents in hippocampal and cortical neurons.

The study provides preclinical evidence supporting BK channels as a potential therapeutic target in Fragile X syndrome.

This research is particularly relevant to the problem of sound sensitivity. In some individuals with autism, sound hypersensitivity can be severely disabling. Fragile X mouse models provide a way to investigate the underlying auditory physiology and test candidate treatments.

However, sound hypersensitivity can arise from several mechanisms, including abnormalities in peripheral auditory processing as well as central neural circuits. A drug that helps one mechanism may not help another.

 

Codabakalner (SPG601)

The most important recent development is the progression of BK-channel activation into human clinical research.

In April 2026, Pedapati and colleagues published a randomised, double-blind, placebo-controlled crossover study of SPG601 in ten adult men with genetically confirmed Fragile X syndrome.

Following a single 800 mg dose, the investigators reported changes in resting-state EEG gamma power and other EEG measures, alongside improvement on a measure of attention and inhibitory control.

Not every measure improved: auditory-evoked gamma outcomes did not show significant treatment effects.

The study was small and examined a single dose, so it cannot establish long-term efficacy. Nevertheless, it provides initial human evidence that BK-channel activation can produce measurable neurophysiological effects.

Read the original study in Scientific Reports

The new autism study

In October 2026, Spinogenix announced that it was adding a Phase IIb study of codabakalner to its CLARITY programme, specifically targeting idiopathic autism.

CLARITY is a Phase 2b/3 basket trial (NCT07439510). The Fragile X part enrols men with full-mutation Fragile X syndrome, and the autism part is a Phase 2b study in adults. According to the ClinicalTrials.gov record, the trial was listed as not yet recruiting in October 2026, with an estimated start date of December 2026 and an estimated primary completion date of February 2030. Codabakalner has FDA Fast Track designation for Fragile X syndrome, and CLARITY has grant support from the FRAXA Research Foundation. Readers should therefore not expect results for several years.

The proposed recruitment strategy is particularly interesting. Participants will be screened using EEG, with enrolment focused on individuals who have elevated resting gamma-band power resembling a pattern observed in Fragile X syndrome.

In the reported EEG analysis, this signature was found in 35 of 159 autistic participants, or approximately 22%. Among adults, the proportion was 23 of 72, or approximately 32%.

The subgroup could not be reliably distinguished from other autistic participants using 27 conventional clinical assessments after statistical correction.

The investigators therefore propose that EEG may identify a biologically relevant subgroup that would otherwise be missed by behavioural assessment alone.

This is an important hypothesis, but it remains to be validated. An EEG pattern resembling that of Fragile X syndrome does not prove that the same molecular defect is present, nor does it establish that an individual will respond to a BK-channel activator.

The decisive question is whether participants selected by this EEG signature experience meaningful clinical improvement compared with placebo.

ClinicalTrials.gov record for CLARITY (NCT07439510)

Spinogenix announcement of the autism Phase 2b study

 

A second BK opener: KER-0193

Codabakalner is no longer the only BK-channel modulator in clinical development. In September 2025, Servier agreed to acquire KER-0193 from Kaerus Bioscience in a deal worth up to $450 million. KER-0193 is an oral small-molecule BK-channel modulator being developed for Fragile X syndrome.

A Phase 1 study in 56 healthy volunteers found it safe and well tolerated, and an EEG substudy was reported to show proof of mechanism. The FDA has granted it orphan drug and rare paediatric drug designations for Fragile X syndrome, and Servier planned to start a Phase 2 trial in Fragile X patients in 2026.

The significance here is that two independent companies are now testing BK-channel modulators in humans. That does not make either drug effective, but it makes the target harder to dismiss. As with codabakalner, the indication is Fragile X syndrome, not autism in general.

Servier's acquisition of KER-0193

 

4. My earlier interest in mefenamic acid (Ponstan)

Another old EpiphanyASD research thread concerned mefenamic acid, marketed as Ponstan, and its possible effects on potassium channels.

Ponstan is widely used as a pain medication in many countries. In Greece it is OTC and very cheap - there is even a liquid version for children. It is very common in India. In the US it is 10 to 100 times more expensive, so buyer beware.

In my 2016 post, I discussed research showing that related fenamate compounds, including meclofenamic acid and diclofenac, can activate Kv7.2/Kv7.3 currents in experimental systems.

This was an intriguing connection because the neuronal M-current is a well-established regulator of excitability.

In a later post, I explored mefenamic acid's multiple biological effects and its possible relevance to sound sensitivity in Monty. This was an individual observation and a mechanistic hypothesis, not evidence from a controlled autism trial.

My 2016 post on mefenamic acid and autism

My later post on fenamates

The lesson from this line of investigation is that drug repurposing can generate useful hypotheses, but a plausible molecular mechanism is only the beginning of the process.

Mefenamic acid has also been the subject of a patent family for autism, “Treatment and prevention of autism and autism spectrum disorders, associated with Knut Wittkowski and ASDERA. The filings cover mefenamic acid and related fenamates, alone or combined with other agents, and describe potassium, chloride and calcium channel modulators. Wittkowski’s published rationale, however, centres mainly on calcium-activated chloride channels (anoctamins), with mefenamic acid’s potassium-channel effects as only part of its pharmacology. ASDERA’s prodrug of mefenamic acid, ASD-002, was licensed to Q BioMed for development in autism with loss of language. A patent shows that an idea has been protected, not that the drug works. There is no mention in the patent that mefenamic acid or its prodrug benefits sound sensitivity.

In some people (Monty and others) a low dose of Ponstan alleviates sound sensitivity almost immediately.

 

5. What about SK, Kv3 and Slack channels?

BK channels are not the only potassium channels that might be relevant to sensory hypersensitivity.

SK channels are another calcium-sensitive potassium-channel family. They help regulate after-hyperpolarisation and the pattern of neuronal firing.

Chlorzoxazone can also affect SK currents, although its effects on these channels are less prominent than its BK-channel effects in the experimental literature. In the 2024 Fragile X mouse study, the investigators found that chlorzoxazone only partially restored impaired SK currents.

This illustrates why it is important not to assume that a drug's behavioural effects arise exclusively from its most prominent molecular target.

Kv3 channels are also relevant to auditory processing. A 2019 study found abnormalities in high-threshold potassium currents in the auditory brainstem of Fragile X mice and investigated Kv3-channel modulators. These experiments suggest that different potassium-channel families may contribute to different aspects of sensory processing.

Read the Kv3 study

That work has continued. Autifony Therapeutics, the company that supplied the Kv3 modulators used in those experiments, lists Fragile X syndrome among the intended uses of its newer Kv3-modulator compounds. A 2026 abstract from a National Fragile X Foundation junior investigator award also reports effects of two Kv3 positive modulators on EEG biomarkers in Fmr1-knockout mice. This is still preclinical, but it is interesting that Kv3 research is now also using EEG measures, the same kind of biomarker approach used in the codabakalner studies.

FRAXA: Potassium channel modulators to treat Fragile X

NFXF 2026 junior investigator awardees

The Yale group behind the Kv3 work, led by Leonard Kaczmarek, also found that loss of FMRP has opposite effects on two different potassium channels: Kv3.1 currents are increased, while Slack currents are decreased. FMRP directly binds the Slack channel and activates it. This is a good illustration of the point made earlier in this post. Within one disorder, one channel may need to be dampened and another boosted, so "potassium-channel activation" is not a single strategy.

The broader point is that sensory hypersensitivity is not necessarily a single biological phenomenon. Different individuals may have different abnormalities in auditory processing, neuronal firing or network synchronisation.

 

6. Where does this leave the channelASD hypothesis?

I would now distinguish three levels of evidence.

First, genetic evidence. Pathogenic variants in several potassium-channel genes can cause neurodevelopmental disorders that include autistic features. This is strong evidence that ion-channel dysfunction can contribute to particular forms of autism. For BK channels, the human evidence is thinner, consisting of isolated cases such as the KCNMA1 disruption reported in 2006, plus the Fragile X link through FMRP.

Second, experimental therapeutic evidence. Studies of chlorzoxazone and other potassium-channel modulators in Fragile X models show that correcting aspects of channel function can improve selected experimental outcomes. Kv3 modulators have shown similar effects on auditory and sensory measures in mice. These findings support further research but do not establish clinical efficacy.

Third, clinical translation. Azetukalner has advanced into regulatory review for epilepsy, with Phase 3 depression studies reporting from 2027. Codabakalner has produced preliminary human EEG and cognitive findings in Fragile X syndrome and is about to be investigated in an EEG-selected autism subgroup, while KER-0193 is following it into Phase 2 in Fragile X.

These developments make the field more promising than it was when I first wrote about channelASD. However, none of these drugs has established efficacy in autism.

The most interesting question is whether we can identify a particular physiological abnormality, establish its mechanism, and then select a drug that corrects that abnormality.

Conclusion

The recent progress in potassium-channel drug development is encouraging. My original interest in channelASD was based on the idea that autism encompasses multiple biological conditions, some of which might be amenable to targeted pharmacological treatment.

Azetukalner shows that Kv7 modulation has reached an advanced stage of clinical development for epilepsy, and its depression trials will show how far the approach extends. Codabakalner is taking BK-channel modulation into a biomarker-enriched autism trial, and KER-0193 gives the BK target a second clinical programme. Earlier work with chlorzoxazone, Kv3 modulators and other compounds provides additional experimental support for investigating potassium channels in Fragile X syndrome and related neurodevelopmental conditions.

The challenge is to move beyond the broad observation that ion channels matter. We need to identify which channel is abnormal, in which individuals, in which direction, and whether correcting it produces a meaningful improvement.

That is the real promise of channelASD: not one treatment for all autism, but the possibility of matching a treatment to a demonstrable biological abnormality.