RT Journal Article SR Electronic T1 Pharmacokinetics of SNX-111, A Selective N-Type Calcium Channel Blocker, in Rats and Cynomolgus Monkeys JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 379 OP 383 VO 25 IS 3 A1 Scott Bowersox A1 Jaap Mandema A1 Katalin Tarczy-Hornoch A1 George Miljanich A1 Robert R. Luther YR 1997 UL http://dmd.aspetjournals.org/content/25/3/379.abstract AB SNX-111, a selective N-type voltage-sensitive calcium channel blocker, is in clinical trials for the treatment of ischemia-induced brain injury and chronic pain. Pharmacokinetic studies were conducted in rats and cynomologus monkeys to determine the disposition of this compound when it is administered for 24 hr by continuous, constant-rate intravenous infusion. Venous blood samples for determination of SNX-111 plasma levels were collected at regular intervals immediately before, during, and after dosing. Plasma concentrations of SNX-111 equivalents were measured by radioimmunoassay. Pharmacokinetic parameters were derived from plasma SNX-111 concentration-time data using a two-compartment pharmacokinetic model. Results showed close correspondences between pharmacokinetic parameters determined for both species. There were no consistent gender- or dose-related differences in calculated kinetic parameters. In all cases, apparent steady-state plasma SNX-111 concentrations were achieved within 2–4 hr of initiating SNX-111 infusion. Steady-state volume of distribution values were ∼40% of body weight, indicating extravascular dissemination of SNX-111 to both extracellular and intracellular fluids. Elimination curves contained two exponential components. The fast component (ratt½,α = 0.375 hr; monkeyt½,α = 0.730 hr) accounted for ∼97% of the unit impulse disposition function. The apparent terminal half-life ranged from 4.61 hr (rat) to 6.48 hr (monkey). Current findings constitute the first description of the pharmacokinetics of a member of the ω-conopeptide family of neuronal calcium channel blockers. The American Society for Pharmacology and Experimental Therapeutics