Blockade of voltage-gated Ca(2)(+) channels on sensory nerves attenuates neurotransmitter release and membrane hyperexcitability associated with chronic pain states. Identification of small molecule Ca(2)(+) channel blockers that produce significant antinociception in the absence of deleterious hemodynamic effects has been challenging. In this report, two novel structurally related compounds, A-686085 and A-1048400, were identified that potently block N-type (IC(5)(0)=0.8 muM and 1.4 muM, respectively) and T-type (IC(5)(0)=4.6 muM and 1.2 muM, respectively) Ca(2)(+) channels in FLIPR based Ca(2)(+) flux assays. A-686085 also potently blocked L-type Ca(2)(+) channels (EC(5)(0)=0.6 muM), however, A-1048400 was much less active in blocking this channel (EC(5)(0)=28 muM). Both compounds dose-dependently reversed tactile allodynia in a model of capsaicin-induced secondary hypersensitivity with similar potencies (EC(5)(0)=300-365 ng/ml). However, A-686085 produced dose-related decreases in mean arterial pressure at antinociceptive plasma concentrations in the rat, while A-1048400 did not significantly alter hemodynamic function at supra-efficacious plasma concentrations. Electrophysiological studies demonstrated that A-1048400 blocks native N- and T-type Ca(2)(+) currents in rat dorsal root ganglion neurons (IC(5)(0)=3.0 muM and 1.6 muM, respectively) in a voltage-dependent fashion. In other experimental pain models, A-1048400 dose-dependently attenuated nociceptive, neuropathic and inflammatory pain at doses that did not alter psychomotor or hemodynamic function. The identification of A-1048400 provides further evidence that voltage-dependent inhibition of neuronal Ca(2)(+) channels coupled with pharmacological selectivity vs. L-type Ca(2)(+) channels can provide robust antinociception in the absence of deleterious effects on hemodynamic or psychomotor function
Keywords : administration & dosage,Administration,Oral,Analgesics,Animals,Calcium,Calcium Channel Blockers,chemistry,Chronic Pain,Dose-Response Relationship,Drug,drug effects,Hek293 Cells,Hemodynamics,Humans,Laboratories,Male,methods,Neurons,Pain,Pain Measurement,physiology,Piperidones,Pressure,Rats,Rats,Sprague-Dawley,secondary,, Novel,Orally,Active, list of elbow injuries
Date of Publication : 2012 Feb 1
Authors : Scott VE;Vortherms TA;Niforatos W;Swensen AM;Neelands T;Milicic I;Banfor PN;King A;Zhong C;Simler G;Zhan C;Bratcher N;Boyce-Rustay JM;Zhu CZ;Bhatia P;Doherty G;Mack H;Stewart AO;Jarvis MF;
Organisation : Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA. Victoria.E.Scott@Abbott.com
Journal of Publication : Biochem Pharmacol
Pubmed Link : https://www.ncbi.nlm.nih.gov/pubmed/22153861
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