Bumetanide has been used for decades to treat fluid retention in those with heart failure or liver or kidney disease. In the brain, it allows chloride ions to leave cells more easily. Scientists researching pediatric seizures think that reducing the chloride inside brain cells helps GABA neurons’ inhibitory functions work better. This led to speculation that bumetanide could be useful in neonatal epilepsy and autism.
In a 2012 study by French researchers including Eric Lemonnier that was published in the journal Translational Psychiatry, 60 patients aged 3 to 11 who had been diagnosed with autism or Asperger’s syndrome were given either placebo or 1mg of bumetanide daily for 3 months. By the end of the study, the children who received bumetanide showed an average reduction of 5.6 points on the Childhood Autism Rating Scale (CARS), which is assessed from observing behavior during videotaped sessions of children playing with their caregiver and questioning the child’s parents. Children taking placebo showed a reduction of 1.8 points (a statistically significant difference). Clinicians in the study rated almost twice as many children who took bumetanide as having made a significant or a small improvement. Stereotyped behavior and restricted interest were the areas of behavior that seemed to improve most after treatment with bumetanide. Patients with milder autism when the study began tended to improve more than those who started out with more severe symptoms. Symptoms returned to previous levels within a month the study’s end.
Bumetanide’s side effects are well known. It can sometimes cause decreases in potassium in the blood (hypokalemia), so the children’s potassium levels were monitored closely. One child was withdrawn from the study for hypokalemia, which can predispose one to cardiac arrhythmias.