Glycerol phenylbutyrate (GPB) is a new generation ammonia scavenger drug and it also is a sigma-2 (σ2) receptor ligand (pKi: 8.02).Glycerol phenylbutyrate may have therapeutic potential in additional conditions such as chronic hepatic encephalopathy or other inherited metabolic disorders. Glycerol phenylbutyrate also has the potential for the treatment of hyperammonemia.

KSK67 is a selective dual antagonist of sigma-2 and histamine H3 receptors with inhibitory effects on H3 receptors, sigma-1, and sigma-2 receptors, with Ki values of 3.2, 1531, and 101 nM, respectively.

A potent, selective, and orally active sigma-1 receptor antagonist with Ki of 1.03 nM.