SCH 50911 is (+)-(S)-5,5-dimethylmorpholinyl-2-acetic acid and is a selective, orally-active and competitive gamma-Aminobutyric acid B GABA(B) receptor antagonist, binds to GABA(B) receptor (IC50: 1.1 uM). SCH 50911 antagonizes GABA(B) autoreceptors, increasing the electrically-stimulated 3H overflow (IC50: 3 uM).