fenigam,4-Amino-3-phenylbutanoic acid,cas:1078-21-3 CAS NO.1078-21-3

  Phenibut, sold under the brand names Anvifen, Fenibut, and Noofen among others, is a central nervous system depressant with anxiolytic and stimulant effects which is used in the treatment of anxiety, insomnia, and for a variety of other indications. It is usually taken by mouth as a tablet, but can also be given as an intravenous infusion.

Side effects of phenibut include sedation, sleepiness, nausea, irritability, agitation, dizziness, and headache, among others.Overdose of phenibut can produce marked central nervous system depression including unconsciousness, although no deaths have been reported. The medication is structurally related to the neurotransmitter γ-aminobutyric acid (GABA), and hence is a GABA analogue. Phenibut is thought to act as a GABAB receptor agonist, similarly to baclofen and γ-hydroxybutyrate (GHB). However, at low concentrations, phenibut mildly increases the concentration of dopamine in the brain, providing stimulatory effects in addition to the anxiolysis.  Subsequent research has found that it is also a potent blocker of α2δ subunit-containing voltage-dependent calcium channels (VDCCs), similarly to gabapentinoids like gabapentin and pregabalin.

Phenibut was developed in the Soviet Union and was introduced for medical use in the 1960s. Today, it is marketed for medical use in Russia, Ukraine, Kazakhstan, and Latvia.  The medication is not approved for clinical use in the United States and most of Europe, but it is also sold on the Internet as a supplement and purported nootropic. Phenibut has been used recreationally and can produce euphoria as well as addiction, dependence, and withdrawal. It is a controlled substance in Australia, and it has been suggested that its legal status should be reconsidered in Europe as well.