Phenibut

Phenibut
Clinical data
Trade namesAnvifen, Fenibut, Noofen, others[1]
Other namesAminophenylbutyric acid; Fenibut; Fenigam; Phenigam; Phenybut; Phenygam; Phenylgamma; Phenigama; PHG; PhGABA; β-Phenyl-γ-aminobutyric acid; β-Phenyl-GABA[2]
Routes of
administration		Common: Oral[3]
Uncommon: Rectal[3]
Drug classGABAB receptor agonist; Gabapentinoid
ATC code
Legal status
Legal status
Pharmacokinetic data
Bioavailability≥63% (250 mg)[5]
MetabolismLiver (minimal)[6][5]
MetabolitesInactive[6]
Onset of actionOral: 2–4 hours[3]
Rectal: 20–30 minutes[3]
Elimination half-life5.3 hours (250 mg)[5]
Duration of action15–24 hours (1–3 g)[3]
ExcretionUrine: 63% (unchanged)[5]
Identifiers
  • 4-Amino-3-phenylbutanoic acid
CAS Number
PubChem CID
ChemSpider
UNII
KEGG
ChEMBL
CompTox Dashboard (EPA)
ECHA InfoCard100.012.800 Edit this at Wikidata
Chemical and physical data
FormulaC10H13NO2
Molar mass179.219 g·mol−1
3D model (JSmol)
Melting point253 °C (487 °F)
  • O=C(O)CC(c1ccccc1)CN
  • InChI=1S/C10H13NO2/c11-7-9(6-10(12)13)8-4-2-1-3-5-8/h1-5,9H,6-7,11H2,(H,12,13) checkY
  • Key:DAFOCGYVTAOKAJ-UHFFFAOYSA-N checkY
  (verify)

Phenibut, sold under the brand name Anvifen among others,[1] is a central nervous system (CNS) depressant with anxiolytic effects, and is used to treat anxiety, insomnia, and for a variety of other indications.[5] It is usually taken orally (swallowed by mouth), but may be given intravenously.[6][5]

Side effects of phenibut can include sedation, sleepiness, nausea, irritability, agitation, dizziness, euphoria, and sometimes headache, among others.[6][7] Overdose of phenibut can produce marked central nervous system depression including unconsciousness.[6][7] The medication is structurally related to the neurotransmitter γ-aminobutyric acid (GABA), and hence is a GABA analogue.[5] Phenibut is thought to act as a GABAB receptor agonist, similarly to baclofen and γ-hydroxybutyrate (GHB).[5] However, at low concentrations, phenibut mildly increases the concentration of dopamine in the brain, providing stimulatory effects in addition to the anxiolysis.[8]

Phenibut was developed in the Soviet Union and was introduced for medical use in the 1960s.[5] Today, it is marketed for medical use in Russia, Ukraine, Belarus, Kazakhstan, and Latvia.[5] The medication is not approved for clinical use in the United States and most of Europe, but it is sold on the Internet as a supplement and purported nootropic.[3][9] Phenibut has been used recreationally and can produce euphoria as well as addiction, dependence, and withdrawal.[3] It is a controlled substance in Australia, and it has been suggested that its legal status should be reconsidered in Europe as well.[3] In Germany, phenibut is not approved as a drug and, as a food supplement, is controlled under the German New Psychoactive Substances Act.[10]

In a 2023 assessment, the U.S. Food and Drug Administration (FDA) determined that phenibut does not meet the definition of a dietary ingredient, thereby making phenibut supplement products misbranded and illegal for marketing.[11] FDA warning letters had been issued to supplement manufacturers marketing phenibut products as adulterated.[12]

  1. ^ a b Drobizhev MY, Fedotova AV, Kikta SV, Antohin EY (2016). "Феномен аминофенилмасляной кислоты" [Phenomenon of aminophenylbutyric acid]. Russian Medical Journal (in Russian). 2017 (24): 1657–1663. ISSN 1382-4368. Archived from the original on 16 September 2017. Retrieved 16 September 2017.
  2. ^ Elks J (14 November 2014). The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. Springer. pp. 69–. ISBN 978-1-4757-2085-3.
  3. ^ a b c d e f g h Cite error: The named reference pmid26693960 was invoked but never defined (see the help page).
  4. ^ Nutrition, Center for Food Safety and Applied (6 March 2023). "Phenibut in Dietary Supplements". FDA. Archived from the original on 23 May 2023. Retrieved 23 May 2023.
  5. ^ a b c d e f g h i j Lapin I (2001). "Phenibut (beta-phenyl-GABA): a tranquilizer and nootropic drug". CNS Drug Reviews. 7 (4): 471–81. doi:10.1111/j.1527-3458.2001.tb00211.x. PMC 6494145. PMID 11830761.
  6. ^ a b c d e Ozon Pharm, Fenibut (PDF), archived from the original (PDF) on 16 September 2017, retrieved 15 September 2017
  7. ^ a b Cite error: The named reference RLS-Phenibut was invoked but never defined (see the help page).
  8. ^ Lapin I (7 June 2006). "Phenibut (beta-phenyl-GABA): a tranquilizer and nootropic drug". CNS Drug Reviews. 7 (4): 471–81. doi:10.1111/j.1527-3458.2001.tb00211.x. PMC 6494145. PMID 11830761.
  9. ^ Cohen PA, Ellison RR, Travis JC, Gaufberg SV, Gerona R (April 2022). "Quantity of phenibut in dietary supplements before and after FDA warnings". Clinical Toxicology. 60 (4): 486–488. doi:10.1080/15563650.2021.1973020. PMID 34550038. S2CID 237594860.
  10. ^ "Anlage NpSG - Einzelnorm". www.gesetze-im-internet.de. Retrieved 7 June 2024.
  11. ^ "Phenibut in Dietary Supplements". US Food and Drug Administration. 12 July 2023. Retrieved 14 September 2024.
  12. ^ "FDA Acts on Dietary Supplements Containing DMHA and Phenibut". US Food and Drug Administration. 29 April 2019. Retrieved 14 September 2024.