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.

A potent and selective sigma-1 receptor antagonist with Ki of 17 nM; shows excellent selectivity over sigma-2 receptor (Ki>1 uM).

Sigma-1 receptor antagonist 2 is a more potent and selective antagonist of sigma 1 receptor (σ1 R, Ki = 3.88 nM) than σ2 receptor (Ki = 1288 nM).