Clinical data
Synonyms CGP-11130; β-(4-Fluorophenyl)-γ-aminobutyric acid; β-(4-Fluorophenyl)-GABA; Baflofen; Fluorophenibut; F-Phenibut; Fluoribut
Routes of
By mouth
CAS Number
PubChem CID
Chemical and physical data
Formula C10H12FNO2
Molar mass 197.209 g·mol−1
3D model (JSmol)

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 and colloquially as fluorobut.


  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. PMC 2044790. PMID 6297646.