Absorption, distribution, metabolism and excretion of SUL-138 in rats and minipigs

SUL-138 is an orally bioavailable 6-chromanol which is in development as therapeutic against Noncommunicable Chronic Diseases (NCDs) including Chronic Heart Failure, Chronic Kidney Disease, Alzheimer's and Parkinson's Disease. The compound improves mitochondrial function by preserving respiration through activation of complex I and IV during disease. Thorough comprehension of preclinical Absorption, Distribution, Metabolism and Excretion (ADME) is pivotal for the safety assessment prior to starting Phase I clinical trials. To this end, a single oral or intravenous dose of [¹⁴C]-SUL-138 at a therapeutic and near Maximum Tolerated Dose (MTD) dose level were administered to rats and minipigs for characterization of ADME properties. Non-radiolabelled SUL-138 and radiolabelled [¹⁴C]-SUL-138 were administered as single oral or intravenous dose to intact and bile duct-canulated rats and to minipigs to investigate pharmacokinetics of total radioactivity and SUL-138, tissue distribution by Quantitative Whole-Body Autoradiography (QWBA), excretion and metabolite profiling. The pharmacokinetic profiles of [¹⁴C]-SUL-138 and SUL-138 indicated rapid absorption, tissue distribution and extensive metabolism in both species. In rats, the QWBA showed that drug-related radioactivity was widely distributed throughout nearly all tissues shortly after dosing. Total radioactivity was completely eliminated; in rats excretion was mainly via the faecal route, whereas in minipigs elimination was equal between the faecal and renal excretory routes. Primary metabolic pathways for clearance of SUL-138 were oxidation, N-dealkylation and glucuronidation. Plasma exposure to the parent was low compared to the main circulating oxidation metabolite M2 and glucuronide conjugate M7 in rats and glucuronide conjugates M7 and M8 in minipigs. In conclusion, ADME properties of SUL-138 are characterized by rapid absorption, wide tissue distribution, extensive metabolism and excretion via the renal and faecal route. Oxidation and glucuronidation are the main metabolic pathways in both nonclinical safety species.