The invention describes a kit and a method useful for analyzing the plasma concentration of an active neuroleptic drug known to have D-1 receptor antagonist properties utilizing labeled [-]trans 6,7,7a,8,9,13b-hexahydro-3-chloro-2-hydroxy-N-methyl-5H-benzo[d]naphth o-[2,1-b]-azepine.
Assay kit and methods for neuroleptic drugs