Systematic (IUPAC) name
Clinical data
Legal status
CAS number
ATC code ?
Chemical data
Formula C4H8N2O2 
Mol. mass 116.11972 g/mol

HA-966 or (±) 3-Amino-1-hydroxy-pyrrolidin-2-one is a molecule used in scientific research as a glycine receptor and NMDA receptor antagonist / low efficacy partial agonist. It has neuroprotective and anticonvulsant,[1] anxiolytic,[2] antinociceptive[3] and sedative / hypnotic[4] effects in animal models. Pilot human clinical trials in the early 1960s showed that HA-966 appeared to benefit patients with tremors of extrapyramidal origin.[4]

The two enantiomers of HA-966 have differing pharmacological activity. The glycine/N-methyl-D-aspartate receptor antagonist activity is specific to the R-(+) enantiomer, whereas the sedative and ataxic effects are specific to the S-(-) enantiomer.[5]

R-(+)-HA-966 did not induce drug-appropriate responding in animals trained to discriminate phencyclidine (PCP) from saline, suggesting that the glycine receptor ligand R-(+)-HA-966 has a significantly different behavioral profile than drugs affecting the ion channel of the NMDA receptor complex.[6]

S-(-)-HA-966 has been described as a "γ-hydroxybutyric acid (GHB)-like agent"[7] and a "potent y-butyrolactone-like sedative",[5] but it shows no affinity for the GABAB receptor (GABABR).[7]


  1. ^ Vartanian MG, Taylor CP. (Nov 1991). "Different stereoselectivity of the enantiomers of HA-966 (3-amino-1-hydroxy-2-pyrrolidinone) for neuroprotective and anticonvulsant actions in vivo.". Neuroscience Letters 133 (1): 109–12.  
  2. ^ Dunn RW, Flanagan DM, Martin LL, Kerman LL, Woods AT, Camacho F, Wilmot CA, Cornfeldt ML, Effland RC, Wood PL, et al. (Apr 1992). "Stereoselective R-(+) enantiomer of HA-966 displays anxiolytic effects in rodents.". European Journal of Pharmacology 214 (2-3): 207–14.  
  3. ^ Näsström J, Karlsson U, Post C. (Feb 1992). "Antinociceptive actions of different classes of excitatory amino acid receptor antagonists in mice.". European Journal of Pharmacology 212 (1): 21–9.  
  4. ^ a b Bonta IL, De Vos CJ, Grijsen H, Hillen FC, Noach EL, Sim AW. (Nov 1971). "1-Hydroxy-3-amino-pyrrolidone-2(HA-966): a new GABA-like compound, with potential use in extrapyramidal diseases.".  
  5. ^ a b Singh L, Donald AE, Foster AC, Hutson PH, Iversen LL, Iversen SD, Kemp JA, Leeson PD, Marshall GR, Oles RJ, et al. (Jan 1990). "Enantiomers of HA-966 (3-amino-1-hydroxypyrrolid-2-one) exhibit distinct central nervous system effects: (+)-HA-966 is a selective glycine/N-methyl-D-aspartate receptor antagonist, but (-)-HA-966 is a potent gamma-butyrolactone-like sedative.". Proc Natl Acad Sci USA. 87 (1): 347–51.  
  6. ^ Singh L, Menzies R, Tricklebank MD. (Sep 1990). "The discriminative stimulus properties of (+)-HA-966, an antagonist at the glycine/N-methyl-D-aspartate receptor.". European Journal of Pharmacology. 186 (1): 129–32.  
  7. ^ a b Morrow BA, Lee EJ, Taylor JR, Elsworth JD, Nye HE, Roth RH. (Nov 1997). "(S)-(-)-HA-966, a gamma-hydroxybutyrate-like agent, prevents enhanced mesocorticolimbic dopamine metabolism and behavioral correlates of restraint stress, conditioned fear and cocaine sensitization.". J Pharmacol Exp Ther. 283 (2): 712–21.