Phenylbutyrate May Reduce Seizures And Support Development

What was studied

Researchers looked at early real-world use of phenylbutyrate in children with 2 rare developmental and epileptic encephalopathies: STXBP1-encephalopathy and SLC6A1-encephalopathy. This was not a clinical trial. Instead, the team did semistructured phone interviews with parents about what happened after their child started the medicine.

The study included 18 children, with a median age of 6 years, who took phenylbutyrate for a median of 6 months. Parents were asked about seizure changes, development, side effects, and toxicity. For children whose seizures were not controlled before treatment, the researchers counted a seizure response as at least a 50% drop in seizures.

What they found

Among the 11 children who had uncontrolled seizures before treatment, 8 had improvement, and all 8 had at least a 50% reduction in seizures. That was a 73% seizure response rate in that subgroup. Almost all families, 17 out of 18, reported some developmental improvement after treatment. Mild side effects were common at the start, including sedation, decreased appetite, and nausea, but these usually went away within 2 to 10 days. One child had severe toxicity, with metabolic acidosis and aspiration pneumonia, and needed intubation.

Limits of the evidence

This was a small study of only 18 children, based on parent phone reports rather than direct testing in a controlled trial. Without a comparison group, the study cannot show that phenylbutyrate was responsible for the seizure or developmental improvements. Parent-reported developmental gains can be hard to measure, and the abstract does not give detailed standardized test results. The treatment period was fairly short, so long-term benefits and risks are still uncertain.

For families and caregivers

This study suggests phenylbutyrate may help some children with STXBP1- or SLC6A1-encephalopathy, for seizures and possibly for development. But the evidence is still early, and side effects were common at first. Because one child had a serious toxicity event, families may want to know that safety monitoring is important, especially when starting treatment.

What to watch next

Larger controlled studies with standard developmental testing and clear safety monitoring would help clarify benefits and risks; families can ask their clinician how changes and side effects would be tracked if this medicine is considered.

Terms in this summary

phenylbutyrate

A medicine already approved for urea cycle disorders that is being studied for possible use in some rare epilepsies.

developmental and epileptic encephalopathy

A group of severe epilepsy conditions in which seizures and the underlying brain disorder can affect development and learning.

STXBP1-encephalopathy

A rare genetic brain disorder that often causes epilepsy and developmental problems.

SLC6A1-encephalopathy

A rare genetic brain disorder that can cause epilepsy, learning problems, and movement or behavior symptoms.

toxicity

Harmful effects from a medicine.

sedation

Unusual sleepiness or drowsiness.

metabolic acidosis

A serious condition where the body becomes too acidic.

aspiration pneumonia

A lung infection that can happen when food, liquid, or vomit goes into the lungs.