Phenibut (Phe)

Phenibut is a γ-aminobutyric acid with a phenyl group in the β-position. β-Phenyl-γ-aminobutyric acid is a derivative of the naturally occurring inhibitory neurotransmitter γ-aminobutyric acid (GABA). The addition of a phenyl ring allows phenibut to cross the blood brain barrier. In chemical structure, phenibut is a phenyl derivative of GABA. Although the calming action is similar to other GABA agonists, phenibut binds to the GABAB metabotropic receptor, the same site responsible for the sedative effects of baclofen (the para-chloro derivative of phenibut) and γ-hydroxybutyrate (GHB), although GHB also acts at the GHB receptor. There is dispute in the literature about whether or not phenibut binds to the GABAA ionotropic receptor, which is responsible for the actions of the benzodiazepines, barbiturates, z-drugs, and for some of the effects of ethanol.