Beta-phenyl-gamma-aminobutyric acid, better known as Phenibut or less commonly Fenibut or Phenybut, is natural derivative of the relaxing neurotransmitter GABA (Gamma amino butyric acid). Sold as a dietary supplement in the US while in Russia sold as a neuropsychotropic drug that is capable of passing the blood-brain barrier. Phenibut is cited as a nootropic for its ability to improve neurological functions. It was discovered in Russia in the 1960's, and has since been used there to treat a wide range of ailments including anxiety and insomnia. The name Phenibut, along with many of the other names for the compound, comes directly from the chemical name for the compound, beta-phenyl-gamma-aminobutyric acid. Phenibut can have unpleasant dose-dependent withdrawal symptoms. Withdrawal symptoms can include acute anxiety and insomnia that can last for up to two weeks afterwards. Withdrawal symptoms, however, are almost always associated with cessation after prolonged usage. Tolerance to phenibut can develop quite rapidly.[citation needed] Anecdotal evidence repeatedly suggests that tolerance and withdrawal can be offset by coadministration of piracetam and possibly other nootropic drugs.