gal021 and Respiratory-Insufficiency

Opioids are potent painkillers but come with serious adverse effects ranging from addiction to potentially lethal respiratory depression. A variety of drugs with separate mechanisms of action are available to prevent or reverse opioid-induced respiratory depression (OIRD).. The authors reviewed human studies on reversal of OIRD using models that describe and predict the time course of pharmacokinetics (PK) and pharmacodynamics (PD) of opioids and reversal agents and link PK to PD.. The PKPD models differ in their basic structure to capture the specific pharmacological mechanisms by which reversal agents interact with opioid effects on breathing. The effect of naloxone, a competitive opioid receptor antagonist, is described by the combined effect-compartment receptor-binding model to quantify rate limitation at the level of drug distribution and receptor kinetics. The effects of reversal agents that act through non-opioidergic pathways, such as ketamine and the experimental drug GAL021, are described by physiological models, in which stimulants act at CO. Model-based drug development is needed to design an 'ideal' reversal agent-that is, one that is not influenced by opioid receptor kinetics, does not interfere with opioid analgesia, has a rapid onset of action with long-lasting effects, and is devoid of adverse effects.

Topics: Analgesics, Opioid; Carotid Body; Doxapram; Drug Design; Humans; Models, Biological; Naloxone; Narcotic Antagonists; Respiratory Insufficiency; Triazines

Opioid-induced respiratory depression is potentially lethal. GAL021 is a calcium-activated potassium (BKCa) channel blocker that causes reversal of opioid-induced respiratory depression in animals due to a stimulatory effect on ventilation at the carotid bodies. To assess in humans whether GAL021 stimulates breathing in established opioid-induced respiratory depression and to evaluate its safety, a proof-of-concept double-blind randomized controlled crossover study on isohypercapnic ventilation (study 1) and subsequent double-blind exploratory study on poikilocapnic ventilation and nonrespiratory end points (study 2) was performed.. In study 1, intravenous low- and high-dose GAL021 and placebo were administrated on top of low- and high-dose alfentanil-induced respiratory depression in 12 healthy male volunteers on two separate occasions. In study 2, the effect of GAL021/placebo on poikilocapnic ventilation, analgesia, and sedation were explored in eight male volunteers. Data are mean difference between GAL021 and placebo (95% CI).. Study 1: Under isohypercapnic conditions, a separation between GAL021 and placebo on minute ventilation was observed by 6.1 (3.6 to 8.6) l/min (P < 0.01) and 3.6 (1.5 to 5.7) l/min (P < 0.01) at low-dose alfentanil plus high-dose GAL021 and high-dose-alfentanil plus high-dose GAL021, respectively. Study 2: Similar observations were made on poikilocapnic ventilation and arterial pCO2. GAL021 had no effect on alfentanil-induced sedation, antinociception and no safety issues or hemodynamic effects became apparent.. GAL021 produces respiratory stimulatory effects during opioid-induced respiratory depression with containment of opioid-analgesia and without any further increase of sedation. Further studies are needed to confirm these preliminary data.

Topics: Adolescent; Adult; Alfentanil; Analgesia; Analgesics, Opioid; Cross-Over Studies; Double-Blind Method; Doxapram; Healthy Volunteers; Hemodynamics; Humans; Large-Conductance Calcium-Activated Potassium Channels; Male; Middle Aged; Potassium Channel Blockers; Respiratory Insufficiency; Triazines

The authors describe the preclinical pharmacological properties of GAL-021, a novel peripheral chemoreceptor modulator.. 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.. 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.. 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.

Topics: Analgesics, Opioid; Animals; Carotid Body; Female; Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; Macaca fascicularis; Male; Mice; Mice, Transgenic; Rats; Rats, Sprague-Dawley; Respiration; Respiratory Insufficiency; Respiratory Mechanics; Triazines

Opioid-induced respiratory depression (OIRD) is a serious and potentially life-threatening complication of opioid overdose, abuse, and misuse. An option to avert OIRD is to treat patients on strong opioids with respiratory stimulants that do not interact with the opioid system and consequently do not compromise opioid analgesic efficacy. The BK-channel blocker GAL021 is a respiratory stimulant acting at K(+) -channels expressed on type 1 carotid body cells. The authors performed a population pharmacokinetic-pharmacodynamic (PKPD) analysis on the ability of GAL021 to reverse alfentanil-induced respiratory depression in 12 male volunteers using an isohypercapnic experimental design. The analysis showed that (1) GAL021 interacts in a multiplicative fashion with alfentanil and GAL021, which predicts that GAL021 efficacy is reduced at low ventilation levels; (2) GAL021 has a rapid onset/offset with a blood-effect site equilibration half-life not different from zero; and (3) GAL021 displays ceiling in its efficacy to reverse OIRD.

Topics: Adult; Analgesics, Opioid; Healthy Volunteers; Humans; Male; Models, Biological; Respiratory Insufficiency; Triazines

Topics: Analgesics, Opioid; Humans; Large-Conductance Calcium-Activated Potassium Channels; Male; Potassium Channel Blockers; Respiratory Insufficiency; Triazines