Cious in the absence of antipsychotic medication (Lane et al., 2008). There are now several synthetic GlyT1 inhibitors in early clinical development, including N-methyl-N-(6-methoxy-1-phenyl-1,2,3,4-tetrahydronaphthalen-2-ylmethyl)aminom ethylcarboxylic acid (SCH 900435 or Org 25935), and 1-methyl-1H-imidazole-4-carboxylic acid (3-chloro-4fluoro-benzyl)-(3-methyl-3-aza-bicyclo[3.1.0]hex-6-yl methy