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

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

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