However, Phenibut FAA is a absolutely free amino acid kind, which is not as soluble but is thought to possess higher bioavailability.GABA-B Receptor Agonist: The first system of motion of phenibut is as an agonist in the GABA-B (gamma-aminobutyric acid variety B) receptors. GABA is the primary inhibitory neurotransmitter in the brain, and its activ