BMS-442606 is an S-enantiomer of 6-hydroxybuspirone and is a 5-HT1A partial agonist. BMS-442606 has advantage of being cleared more slowly from blood compared to the R-enantiomer, but R form showed higher affinity and selectivity for the 5HT1A receptor compared to the S-isomer. Because both isomers together with racemic form were well tolerated and was not found any advantage of one of the enantiomers of over the racemic form. Finally, racemic form was chosen for further clinical development.