Tricyclic Triazoles as σ Receptor Antagonists for Treating Pain.

The synthesis and pharmacological activity of a new series of 5a,7,8,8a-tetrahydro-4,6-pyrrolo[3,4-][1,2,3]triazolo[1,5-][1,4]oxazine derivatives as potent sigma-1 receptor (σR) ligands are reported. A lead optimization program aimed at improving the aqueous solubility of parent racemic nonpolar derivatives led to the identification of several σR antagonists with a good absorption, distribution, metabolism, and excretion in vitro profile, no off-target affinities, and characterized by a low basic p (around 5) that correlates with high exposure levels in rodents. Two compounds displaying a differential brain-to-plasma ratio distribution profile, and , exhibited a good analgesic profile and were selected as preclinical candidates for the treatment of pain.