Phenibut

β-phenyl-GABA

What it isGABA-B agonist and alpha-2-delta ligand; sold as a supplement, prescribed in some countries.

Why this oneIt produces anxiolysis with GABA-B agonism, a mechanism no approved anxiolytic uses.

What limits it⚑ Severe dependence with a baclofen-like withdrawal syndrome including delirium and seizures. Unregulated content.

FDA-approved for

NO BOXED WARNINGS

Principal riskSevere dependence with a baclofen-like withdrawal

Therapeutic safety burden2 / 4

Overdose danger3 / 4

Weight-gain liability0 / 4

Sedation liability1 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk4 / 4

Defining liabilityCNS depression; dependence and severe withdrawal with excessive use