GAL-021 is being developed as a novel breathing control modulator to preserve respiratory drive and protect patients from respiratory impairment due to opioids and other modalities. Using inside-out patches in GH3 cells, GAL-021 exerts concentration-dependent inhibition of single-channel KCa1.1 activity. When evaluated against 12 different cardiac ion channels, inhibition is 35% or less at 30 μM. No significant kinase inhibition is observed at 10 μM. At 30 μM in the radioligand binding assays, interactions (defined as >50% radioligand displacement) are detected at adenosine A1 (65% I), A2A (79% I, IC ₅₀ approximately 5μM), and A3 (93% I; IC ₅₀ approximately 1 μM) receptors, at 5-HT2B receptors (60% I; IC ₅₀ approximately 30 μM).

Intravenously administered GAL-021 attenuates opiate-induced respiratory depression in rats and nonhuman primates without affecting morphine analgesia in rats. GAL-021 ventilatory stimulation in rats is attenuated by carotid sinus nerve transection. GAL-021 ventilatory stimulation is attenuated in mice lacking the pore-forming α-subunit of the KCa 1.1 channel.