NBI-98782(alpha-dihydrotetrabenazine) is a vesicular monoamine transporter (VMAT2) inhibtior with an Ki value of 0.97 nM.IC50 value: 0.97± 0.48 nM Target: VMAT2The (+)-isomer showed high affinity in vitro (Ki = 0.97 +/- 0.48 nM) for the vesicular monoamine transporter (VMAT2) in rat brain striatum, whereas the (-)-isomer was inactive (Ki = 2.2 +/- 0.3 microM). Each isomer was then synthesized in carbon-11 labeled form, and regional brain biodistributions in mice determined after intravenous injection.