Phenibut

Beta-phenyl-gamma-aminobutyric acid, better known as Phenibut or less commonly Fenibut or Phenybut, is a neuropsychotropic drug, derived from the neurotransmitter GABA that is capable of passing the blood brain barrier. It was discovered in Russia in the 1960's, and has been used there since for a wide range of ailments including anxiety and insomnia. Phenibut is cited as a nootropic (that is, "smart drug") for its ability to improve neurological functions.

The name Phenibut, along with many of the other names for the compound, comes directly from the chemical name for the compound, beta-phenyl-gamma-aminobutyric acid.

Chemically, Phenibut is similar to baclofen and phenylethylamine, and predictably behaves similar to these compounds. Phenibut is a GABAB receptor agonist, with slight activity at GABAA receptors. When coadministered with phenylethylamine, Phenibut antagonizes its effects, which can include hyperthermia, promotion of seizure activity, and promotion of anxiety.