Phenibut acts as a full agonist of the GABAB receptor, similarly to baclofen. It has between 30- to 68-fold lower affinity for the GABAB receptor than baclofen, and, in accordance, is used at far higher doses in comparison. ("R")-Phenibut has more than 100-fold higher affinity for the GABAB receptor than does ("S")-phenibut; hence, ("R")-phenibut is the active enantiomer at the GABAB receptor. At very high concentrations, phenibut reportedly also acts as an agonist of the GABAA receptor, which is the receptor responsible for the actions of the benzodiazepines, barbiturates, and alcohol.