Substituted 3-isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-pyrido[2,1-a]isoquinolin-2-ol compounds are disclosed that are inhibitors of the vesicular monoamine transporter 2 (VMAT2). The compounds of this invention have the structure: wherein R1 is as defined herein, including stereoisomers and pharmaceutically acceptable salts and solvates thereof. Also disclosed are compositions containing a compound of this invention in combination with a pharmaceutically acceptable carrier, as well as methods relating to the use in a subject in need thereof.