Validation of an LC-MS/MS method to quantify the new TRPC6 inhibitor SH045 (larixyl N-methylcarbamate) and its application in an exploratory pharmacokinetic study in mice

TRPC6 (transient receptor potential cation channels; canonical subfamily C, member 6) are widespread localized in mammalian organs like kidney and lung and associated with progressive proteinuria and pathophysiological pulmonary alterations like reperfusion edema or lung fibroses. However, the understanding of TRPC6 channelopathies is still at the beginning. Recently, by chemical diversification of (+)-larixol originating from Larix decidua resin traditionally used for inhalation, its methyl carbamate congener, named SH045, was obtained and identified in functional assays as highly potent, subtype-selective inhibitor of TRPC6. To pave the way for use of SH045 in animal disease models we aimed to develop a capable bioanalytical method and to provide exploratory pharmacokinetic data for this promising derivative. According to international guidelines, a robust and selective LC-MS/MS method based on MRM detection in positive ion mode was established and validated for quantification of SH045 in mice plasma, whereby linearity and accuracy were demonstrated for the range of 2-1600 ng/mL.
Applying this method, the plasma concentration time course of SH045 following single intraperitoneal administration (20 mg/kg body weight) revealed a rather short half-life of 1.3 hours. However, the pharmacological profile of SH045 is promising as five hours after administration plasma levels still remained sufficiently higher than published low nanomolar IC50 values.
Summarizing, the LC-MS/MS quantification method and exploratory pharmacokinetic data provide important prerequisites for experimental pharmacological TRPC6 modulation and translational treatment of TRPC6 channelopathies.