Identification and Characterization of GAL-021 as a Novel Breathing Control Modulator.
BACKGROUND
The authors describe the preclinical pharmacological properties of GAL-021, a novel peripheral chemoreceptor modulator.


METHODS
The ventilatory effects of GAL-021 were characterized using tracheal pneumotachometry (n = 4 to 6), plethysmography (n = 5 to 6), arterial blood gas analyses (n = 6 to 11), and nasal capnography (n = 3 to 4) in naive animals and those subjected to morphine-induced respiratory depression. Morphine analgesia in rats was evaluated by tail-flick test (n = 6). Carotid body involvement in GAL-021 ventilatory effects was assessed by comparing responses in intact and carotid sinus nerve-transected rats. Hemodynamic effects of GAL-021 were evaluated in urethane-anesthetized rats (n = 7). The pharmacological profile of GAL-021 in vitro was investigated using radioligand binding, enzyme inhibition, and cellular electrophysiology assays.


RESULTS
GAL-021 given intravenously stimulated ventilation and/or attenuated opiate-induced respiratory depression in rats, mice, and nonhuman primates, without decreasing morphine analgesia in rats. GAL-021 did not alter mean arterial pressure but produced a modest increase in heart rate. Ventilatory stimulation in rats was attenuated by carotid sinus nerve transection. GAL-021 inhibited KCa1.1 in GH3 cells, and the evoked ventilatory stimulation was attenuated in Slo1 mice lacking the pore-forming α-subunit of the KCa1.1 channel.


CONCLUSIONS
GAL-021 behaved as a breathing control modulator in rodents and nonhuman primates and diminished opioid-induced respiratory depression without compromising opioid analgesia. It acted predominantly at the carotid body, in part by inhibiting KCa1.1 channels. Its preclinical profile qualified the compound to enter clinical trials to assess effects on breathing control disorders such as drug (opioid)-induced respiratory depression and sleep apnea.
From the Department of Drug Discovery, Galleon Pharmaceuticals, Inc., Horsham, Pennsylvania (F.J.G., S.D., S.M.B., R.G., C.I., A.K., S.P., V.P., D.R., R.W., J.C.M., D.E.M.); Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania (T.H.); and Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina (R.L.W., M.R.V.S.).
Francis J
FJ
Golder
Scott
S
Dax
Santhosh M
SM
Baby
Ryan
R
Gruber
Toshinori
T
Hoshi
Courtney
C
Ideo
Andrew
A
Kennedy
Sean
S
Peng
Veljko
V
Puskovic
David
D
Ritchie
Richard
R
Woodward
Robert L
RL
Wardle
Michael R
MR
Van Scott
James C
JC
Mannion
D Euan
DE
MacIntyre
D000701:Analgesics, Opioid / Q000633:toxicity; D000818:Animals; D002344:Carotid Body / Q000187:drug effects* / Q000502:physiology; D005260:Female; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / Q000037:antagonists & inhibitors* / Q000502:physiology; D008252:Macaca fascicularis; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D051381:Rats; D017207:Rats, Sprague-Dawley; D012119:Respiration / Q000187:drug effects; D012131:Respiratory Insufficiency / Q000139:chemically induced / Q000503:physiopathology / Q000517:prevention & control; D015656:Respiratory Mechanics / Q000187:drug effects* / Q000502:physiology; D014227:Triazines / Q000494:pharmacology* / Q000627:therapeutic use
D000701:Analgesics, Opioid; C465449:Kcnma1 protein, mouse; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D014227:Triazines; C000593146:GAL021