22/08/2026
L1-79: Is it a mood stabilizer?
L1-79 is a new investigational drug being developed for autism, but it is important to understand that it is not a conventional mood stabilizer and not an antipsychotic.
L1-79 is also known as DL-alpha-methyltyrosine (racemetirosine). Its mechanism is quite different from commonly used antipsychotic medicines. It inhibits tyrosine hydroxylase, an enzyme involved in the production of catecholamines such as dopamine and noradrenaline.
In contrast, antipsychotics such as risperidone and aripiprazole primarily act on dopamine and serotonin receptors and are used in autism mainly for associated irritability, aggression and severe behavioral problems, rather than the core features of autism. L1-79 is being investigated specifically for core autism symptoms, particularly social-communication difficulties.
So, L1-79 should not simply be considered another antipsychotic or mood stabilizer. It represents a different pharmacological approach.
Importantly, L1-79 remains an investigational treatment; Phase 2 studies have been completed and further Phase 3 development is planned. It should therefore not be considered an established routine treatment for autism yet.
Dr. Sumeet Dhawan
DM Pediatric Neurology
Neurologist | Autism | ADHD | Speech & Development
📞 8208537763
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