SA4503 is a potent sigma-1 (σ1 receptor) agonist. It shows 100 fold higher affinity for σ1 than σ2 receptor with IC₅₀ values of 17.4 nM and 1784 nM against 200 nM (+)-pentazocine for binding σ receptor in guinea pig brain membranes. It shows Ki values of 4.6 nM and 63.1 nM for σ1 and σ2 sites respectively in guinea pig brain homogenates. It enhances recovery of lost sensorimotor function in a rat model of stroke. Based on viral screens, modulators of sigma receptor are predicted to show activity against SARS-CoV-2.