Safety, pharmacokinetics, and pharmacodynamics in healthy Chinese volunteers treated with SC0062, a highly selective endothelin-A receptor antagonist.

This study evaluated the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and food effects (FE) of SC0062, a highly active endothelin-A (ETA ) receptor antagonist, in healthy subjects. The primary objectives of this first-in-human phase I study, comprised of single-ascending-dose, multiple-ascending-dose, and FE parts, were to characterize the safety and tolerability of SC0062, and FE. The secondary objectives were to determine the PK behavior of SC0062 and its major active metabolite M18, whereas exploratory objectives focused on PD effects, principally effects on endothelin-1 (ET-1) and total bile acids (TBA). Single doses of 10 to 100 mg and multiple daily doses of 20 and 50 mg for 6 days were well tolerated. SC0062 was rapidly absorbed and plasma exposure of SC0062 and M18 increased disproportionately with dose, achieving steady state by day 3, with accumulation ratios of 1.22 and 1.89 on day 6 for SC0062 and M18, respectively. The geometric mean (geometric standard deviation) terminal elimination half-life (t1/2 ) values of SC0062 and M18 were 7.25 (1.70) h and 13.73 (1.32) h, respectively. Plasma ET-1 concentrations were dose-proportional, whereas plasma TBA concentrations behaved erratically. Following a single 50 mg dose of SC0062 after a high-fat meal, Cmax values for SC0062 and M18 increased by 41% and 32%, respectively, and median Tmax values for SC0062 were 3 h longer than fasting values; exposure was unaffected. These favorable safety, PK, and PD results provide a foundation for further studies of SC0062 in pulmonary arterial hypertension, chronic kidney disease, and other relevant indications.