Clinical data
Other namesCGP-11130; β-(4-Fluorophenyl)-γ-aminobutyric acid; β-(4-Fluorophenyl)-GABA; Baflofen; Fluorophenibut; F-Phenibut; Fluoribut
Routes of
By mouth
  • 4-Amino-3-(4-fluorophenyl)butanoic acid
CAS Number
PubChem CID
Chemical and physical data
Molar mass197.209 g·mol−1
3D model (JSmol)
  • C1=CC(=CC=C1C(CC(=O)O)CN)F
  • InChI=1S/C10H12FNO2/c11-9-3-1-7(2-4-9)8(6-12)5-10(13)14/h1-4,8H,5-6,12H2,(H,13,14)

4-Fluorophenibut (developmental code name CGP-11130; also known as β-(4-fluorophenyl)-γ-aminobutyric acid or β-(4-fluorophenyl)-GABA) is a GABAB receptor agonist which was never marketed.[1] It is selective for the GABAB receptor over the GABAA receptor (IC50 = 1.70 μM and > 100 μM, respectively).[1] The drug is a GABA analogue and is closely related to baclofen (β-(4-chlorophenyl)-GABA), tolibut (β-(4-methylphenyl)-GABA), and phenibut (β-phenyl-GABA).[1] It is less potent as a GABAB receptor agonist than baclofen but more potent than phenibut.[1]

The substance is sometimes referred to as 4F-phenibut or F-phenibut or baflofen and colloquially as fluorobut.

Legal status

F-Phenibut is a prohibited substance in Lithuania[2] and Hungary.[3]


  1. ^ a b c d Bowery NG, Hill DR, Hudson AL (1983). "Characteristics of GABAB receptor binding sites on rat whole brain synaptic membranes". Br. J. Pharmacol. 78 (1): 191–206. doi:10.1111/j.1476-5381.1983.tb09380.x. PMC 2044790. PMID 6297646.
  2. ^ "RINKOS RIBOJIMO PRIEMONĖS FENIBUTUI!". ntakd.lrv.lt (in Lithuanian). Retrieved 2020-01-27.
  3. ^ MAGYARORSZÁG HIVATALOS LAPJA. Retrieved 2021-04-28.