Phase I clinical trial evaluating the safety, tolerance, pharmacokinetics and pharmacodynamics of HSK21542 injection in healthy volunteers

HSK21542 injection is a new peripheral kappa opioid receptor (KOR) agonist. To evaluate its safety, tolerability, pharmacokinetics and pharmacodynamics, this study was conducted in healthy volunteers, consisting of two parts: a single ascending dose (0.2–3.375 μg/kg, 15‐min infusion) and different infusion durations (0.2 and 1 μg/kg, 2‐ or 15‐min infusion). The area under the plasma concentration‐time curve (AUC) and peak concentration (Cmax) of HSK21542 were dose‐linear among 0.2–3.375 μg/kg. After intravenous injection, HSK21542 was rapidly eliminated with a half‐life (t1/2) of 1.5 h, and the majority (48.02%) of the dose was excreted unchanged in urine. Pharmacodynamic results showed that HSK21542 increased prolactin release and reached a peak at 1–2 h after administration but had no significant effect on vasopressin levels. There was a brief increase in urine volume within the initial 2 h after administration. HSK21542 was well tolerated; most of the adverse effects (AEs) in the trial group were grade 1, and only 2 cases (4.0%) were grade 2. The main AE was paresthesia, which appeared in 42% (21/50) in the trial group. No serious adverse event (SAE) was observed. No subject withdrew early due to AEs. These results suggest that HSK21542 may be a potential treatment for pain and pruritic conditions. In this study, subjects were enrolled in eight dose cohorts and received a single intravenous bolus dose of 0.2–3.375 μg/kg HSK21542, and different infusion times were also evaluated. Pharmacodynamic studies showed that it increased prolactin release but had no significant effect on urine volume and vasopressin levels.