Phenibut
Encyclopedia
β-Phenyl-γ-aminobutyric acid, better known as phenibut or less commonly fenibut or phenybut, is a derivative of the naturally occurring inhibitory neurotransmitter γ-aminobutyric acid
Gamma-aminobutyric acid
γ-Aminobutyric acid is the chief inhibitory neurotransmitter in the mammalian central nervous system. It plays a role in regulating neuronal excitability throughout the nervous system...

 (GABA). The addition of a phenyl ring allows phenibut to cross the blood brain barrier. Phenibut is sold as a dietary supplement in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, while in Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

 it is sold as a neuropsychotropic drug. It has been reported by some to possess nootropic
Nootropic
Nootropics , also referred to as smart drugs, brain steroids, memory enhancers, cognitive enhancers, and intelligence enhancers, are drugs, supplements, nutraceuticals, and functional foods that improve mental functions such as cognition, memory, intelligence, motivation, attention, and concentration...

 actions for its ability to improve neurological functions, however other researchers had not previously observed these effects. However, it is generally accepted that phenibut has anxiolytic
Anxiolytic
An anxiolytic is a drug used for the treatment of anxiety, and its related psychological and physical symptoms...

 effects in both animal models and in humans. Phenibut was discovered in the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 in the 1960s, and has since been used there to treat a wide range of ailments including post-traumatic stress disorder, anxiety, and insomnia.

The name phenibut, along with many of the other names for the compound, comes directly from the chemical name for the compound, β-phenyl-γ-aminobutyric acid.

History

Phenibut was synthesized at the I. M. Herzen Leningrad
Leningrad
Leningrad is the former name of Saint Petersburg, Russia.Leningrad may also refer to:- Places :* Leningrad Oblast, a federal subject of Russia, around Saint Petersburg* Leningrad, Tajikistan, capital of Muminobod district in Khatlon Province...

 Pedagogical Institute USSR and the Institute of Experimental Medicine, Academy of Medical Sciences USSR by Professor V. V. Perekalin's team.

Phenibut is mandated standard equipment in a Russian cosmonaut's medical kit. The use of "conventional" tranquilizers for stress and anxiety makes patients drowsy, which was deemed unacceptable for cosmonauts; phenibut, however, lowers stress levels without adversely affecting performance. In 1975 phenibut was included in the cosmonauts' kit for those who participated in the Apollo-Soyuz joint mission
Apollo-Soyuz Test Project
-Backup crew:-Crew notes:Jack Swigert had originally been assigned as the command module pilot for the ASTP prime crew, but prior to the official announcement he was removed as punishment for his involvement in the Apollo 15 postage stamp scandal.-Soyuz crew:...

.

General information

In chemical structure, phenibut is a phenyl derivative of GABA. Although the calming action is similar to other GABA agonists, 4-amino-3-phenylbutyric acid binds the GABAB metabotropic receptor
Metabotropic receptor
Metabotropic receptor is a subtype of membrane receptors at the surface or in vesicles of eukaryotic cells.In the nervous system, based on their structural and functional characteristics, neurotransmitter receptors can be classified into two broad categories: metabotropic and ionotropic receptors...

, the same site responsible for the sedative effects of baclofen
Baclofen
Baclofen is a derivative of gamma-aminobutyric acid . It is primarily used to treat spasticity and is under investigation for the treatment of alcoholism....

 (the para-chloro derivative of phenibut) and γ-hydroxybutyrate
Gamma-Hydroxybutyric acid
γ-Hydroxybutyric acid , also known as 4-hydroxybutanoic acid and sodium oxybate when used for medicinal purposes, is a naturally occurring substance found in the central nervous system, wine, beef, small citrus fruits, and almost all animals in small amounts. It is also categorized as an illegal...

 (GHB), although GHB also acts at the GHB receptor
GHB receptor
Gamma-hydroxybutyrate receptor or GHB receptor , originally identified as GPR172A, is a G protein-coupled receptor that binds gamma-Hydroxybutyric acid .-History:...

. 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 benzodiazepine
Benzodiazepine
A benzodiazepine is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a diazepine ring...

s, barbiturate
Barbiturate
Barbiturates are drugs that act as central nervous system depressants, and can therefore produce a wide spectrum of effects, from mild sedation to total anesthesia. They are also effective as anxiolytics, as hypnotics, and as anticonvulsants...

s, z-drugs, and for some of the effects of ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

. According to Allikmetz and Ryage (1983) and Shulgina (1986) phenibut does bind to the GABAA receptor, but according to Lapin (2001) it does not. In the case of the former, it is argued that the GABAA binding only occurs at higher concentrations.

The literature that supports the nootropic effects of phenibut also suggest it elicits tranquilizing effects, reduction of stress and anxiety, improvement of impaired sleep, and the potentiation of the effects of tranquilizers, narcotics, and neuroleptics. It is also suggested to have an anticonvulsant effect, though studies on other GABAB agonists, such as the phenibut analogues baclofen and GHB, have shown them to act as potential convulsant
Convulsant
A convulsant is a drug which induces convulsions and/or epileptic seizures, the opposite of an anticonvulsant. These drugs generally act as stimulants at low doses, but are not used for this purpose due to the risk of convulsions and consequent excitotoxicity...

s. It should be noted, however, that GHB and baclofen (to a lesser extent) act on the convulsion-inducing GHB receptor
GHB receptor
Gamma-hydroxybutyrate receptor or GHB receptor , originally identified as GPR172A, is a G protein-coupled receptor that binds gamma-Hydroxybutyric acid .-History:...

, which phenibut does not.

Physical properties

Phenibut is a white crystalline powder and the taste is sour. It is very easily soluble in water, soluble in alcohol, and the pH of a 2.5% water solution is between about 2.3 and 2.7.

Doses

Commonly recommended doses are 250–1500 mg, twice daily, or as needed. This is up to the discretion of the health care practitioner as it pertains to patient needs. At higher doses above 40 mg/kg, a lowering of body temperature may occur along with muscle relaxation.

Chemistry

Structurally, phenibut is γ-aminobutyric acid with a phenyl group
Phenyl group
In organic chemistry, the phenyl group or phenyl ring is a cyclic group of atoms with the formula C6H5. Phenyl groups are closely related to benzene. Phenyl groups have six carbon atoms bonded together in a hexagonal planar ring, five of which are bonded to individual hydrogen atoms, with the...

 in the β position. Only the R enantiomer
Enantiomer
In chemistry, an enantiomer is one of two stereoisomers that are mirror images of each other that are non-superposable , much as one's left and right hands are the same except for opposite orientation. It can be clearly understood if you try to place your hands one over the other without...

 is biologically active. It has structural similarities to baclofen (lacking only a chlorine atom in the para-position of the phenyl group) and phenylethylamine.

Pharmacology

The pharmacological effects of phenibut are similar to baclofen, but less potent per milligram of dosage.

Phenibut exerts it effects by being an agonist at the metabotropic GABA
Gabâ
Gabâ or gabaa, for the people in many parts of the Philippines), is the concept of a non-human and non-divine, imminent retribution. A sort of negative karma, it is generally seen as an evil effect on a person because of their wrongdoings or transgressions...

B receptor, and at higher doses also at the ionotropic GABAA receptor.

Additionally, 4-amino-3-phenylbutyric acid antagonizes the effects of phenylethylamine. Furthermore, phenibut has been shown to enhance levels of dopamine.

Contraindications and side effects

The literature reports that phenibut has almost no negative side effects, with only an increase in sleepiness observed, however this effect is not nearly as pronounced as with benzodiazepine usage. Tolerance has been reported with extended use of high doses (e.g. 5–10 grams) of 4-amino-3-phenylbutyric acid.

There are numerous reports of withdrawal symptoms on Internet blogs and a medically documented case of withdrawal involving severe anxiety, tremors agitation, psychosis, hallucinations and a complaint of insomnia similar to baclofen withdrawal, consistent with its GABAB agonist properties. There has been no systematic study of this problem.

Phenibut is not to be mixed with alcohol, sedatives, or prescription medication without consulting with a health-care professional.

Persons on MAO inhibitors
Monoamine oxidase inhibitor
Monoamine oxidase inhibitors are a class of antidepressant drugs prescribed for the treatment of depression. They are particularly effective in treating atypical depression....

 or epilepsy medications
Anticonvulsant
The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...

 like carbamazepine
Carbamazepine
Carbamazepine is an anticonvulsant and mood-stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder, as well as trigeminal neuralgia...

 or oxcarbazepine
Oxcarbazepine
Oxcarbazepine is a anticholinergic anticonvulsant and mood stabilizing drug, used primarily in the treatment of epilepsy. It is also used to treat anxiety and mood disorders, and benign motor tics...

should consult with their physician or pharmacist prior to supplementation with phenibut. Some evidence suggests that phenibut can modulate the function of some epilepsy medications.
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