Almorexant HCl is a potent and competitive dual orexin 1 receptor (OX1)/orexin 2 receptor (OX2) antagonist with Ki values of 1.3 and 0.17 nM for OX1 and OX2, respectively.

SB-408124 is a non-peptide antagonist for OX1 receptor with Ki of 57 nM and 27 nM in both whole cell and membrane, respectively, and exhibits 50-fold selectivity over OX2 receptor.

SB-334867 free base is a selective non-peptide orexin OX1 receptor antagonist with pKb of 7.2.