SAGE-324

A next-generation synthetic neuroactive-steroid GABA-A positive allosteric modulator engineered for once-daily oral dosing, investigated by Sage and Biogen for essential tremor and epilepsy.

SAGE-324 is an investigational compound whose safety profile is defined chiefly by the mechanism-based consequences of strong GABA-A potentiation. In the randomized Phase 2 KINETIC trial, the most common treatment-emergent adverse events were somnolence, dizziness, fatigue and balance disorder, a pattern typical of central nervous system depressants that enhance inhibitory tone.

These effects raise theoretical concerns about additive sedation when combined with alcohol, benzodiazepines, opioids or other GABAergic and depressant agents, and about impairment of tasks requiring alertness and motor coordination. Because the compound remains in clinical development, its long-term safety, withdrawal characteristics, drug-interaction profile and use in pregnancy, hepatic impairment or the elderly have not been fully characterized. It should be regarded as a research agent that is not approved for human use outside of supervised clinical trials.

SAGE-324 emerged from Sage Therapeutics' neuroactive-steroid discovery program, the same platform that produced the intravenous postpartum-depression drug brexanolone and the oral agent zuranolone (SAGE-217). Whereas early neurosteroid therapeutics were limited by short half-lives and parenteral administration, SAGE-324 was designed as a next-generation analog with a duration of action long enough for once-daily oral use. The program advanced into essential tremor, a large and historically underserved movement-disorder indication, through the Phase 2 KINETIC study (NCT04305275).

Conducted between May 2020 and February 2021, KINETIC randomized 69 participants to 60 mg of SAGE-324/BIIB124 or placebo once daily for 28 days and reported a statistically significant reduction in upper-limb tremor on the TETRAS performance subscale, with results published in Movement Disorders in 2024. The compound was co-developed under a collaboration with Biogen, which assigned it the parallel code BIIB124, and it has been discussed alongside other emerging GABAergic and ion-channel strategies in reviews of essential-tremor drug development.

Within neuropharmacology, SAGE-324 is regarded as a notable test of whether the potent inhibitory pharmacology of neuroactive steroids can be harnessed for chronic oral treatment of a movement disorder rather than for acute psychiatric indications. Commentators have highlighted its positive Phase 2 signal in essential tremor as encouraging, given the limited and often poorly tolerated pharmacological options for that condition, while also noting that dose-limiting sedation is the central challenge for GABA-A potentiators of this class.

It is frequently cited in the context of the broader neurosteroid renaissance that followed brexanolone and zuranolone, and in reviews of emerging tremor and antiseizure therapeutics as an example of extrasynaptic-active GABA-A modulation. Because it remains investigational and relatively niche, it has little presence outside specialist literature and no standing as a consumer or nootropic compound.