Mass balance, pharmacokinetics and pharmacodynamics of intravenous HSK3486, a novel anaesthetic, administered to healthy subjects.

AIMS: This trial (NCT03751956) investigated the mass balance, pharmacokinetics and pharmacodynamics of HSK3486, a novel anaesthetic, in healthy subjects. METHODS: A single dose of 0.4 mg/kg [14 C]HSK3486 was administered to six healthy subjects. Blood, urine and faecal samples were collected, analysed for radioactivity, unchanged HSK3486 and profiled for metabolites. The Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale and vital signs were closely monitored during the study. RESULTS: The mean recovery of total radioactivity in excreta was 87.3% in 240 h, including 84.6% in urine and 2.65% in faeces. The exposure (AUC0-t ) of total radioactivity was much higher than that of unchanged HSK3486 in plasma, indicating there were circulating metabolites in plasma. The glucuronide conjugate of HSK3486 (M4) was found as the only major circulating metabolite in plasma (79.3%), while unchanged HSK3486 accounted for only 3.97% of the total radiation exposure. M4 also resulted in a longer estimated elimination half-life (t1/2 ) of total radioactivity than that of unchanged HSK3486 in plasma. Fortunately, the metabolite was detected to be not specific to red blood cells and was suggested to be nonhypnotic and nontoxic. All the subjects were quickly anaesthetized (2 min) after drug administration and woke up smoothly after a short time (5.5-14.1 min) with few residual effects. The only adverse event in the study was mild (grade 1) and consisted of hypotension. CONCLUSION: HSK3486 is a promising anaesthetic candidate with rapid onset of action and clear absorption, distribution, metabolism, excretion (ADME) processes. HSK3486 showed favourable pharmacokinetic characteristics, pharmacodynamic responses and safety at the study dose.