Pharmacokinetic study of Sudaxine in dog plasma using novel LC-MS/MS method

Context Sudaxine is a novel respiratory stimulant that increases ventilatory drive via NO+-thiolate signaling and is under development for reversal of opioid-induced respiratory depression and other critical care indications. Objective This study investigates the pharmacokinetic characteristics after intravenous administration of Sudaxine by using a simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Materials and methods A sensitive LC-MS/MS method was validated to determine the concentration of Sudaxine in beagle dog plasma after intravenous administration of Sudaxine at (3, 10, 30, and 100 mg/kg). Blood samples (1 mL) were collected at designated time points and SDX concentration was measured for pharmacokinetic study. Results The calibration curve was linear within the range of 50-5,000 ng/mL with the lower limit of quantification at 50 ng/mL. The C-Tmax for all doses was reached at 10 minutes (T-max). Over the dose range studied, average concentration - time curves and systemic exposure (C-Tmax and AUC(0-t)) increased to Sudaxine dose. The terminal half-life of Sudaxine in dogs ranged from 10 to 30 minutes and about 17.3 +/- 1.0% of Sudaxine was protein-bound in dog plasma. Discussion and conclusions We developed a novel LC-MS/MS method of Sudaxine detection and quantification and determined its pharmacokinetic profiles after intravenous administration in canine subjects. Sudaxine followed first-order kinetics with rapid dose-dependent clearance rates and short half-life making it an ideal candidate for use in a critical care setting with intramuscular or IV administration.