Determination of EC50 of Dexmedetomidine Hydrochloride Causing Disappearance of Explicit Memory by Process Dissociation Procedure / 医药导报

ABSTRACT

Objective To determine the EC50 of dexmedetomidine hydrochloride ( DEX) which causes disappearance of explicit memory by process dissociation procedure (PDP). Methods Forty patients those who had senior middle school or higher educational background undergoing lower extremity surgery with grade ASA Ⅰ or Ⅱ, without hearing impairment, dysphasia,nervous system disorders,and having no drugs in the treatment of the central nervous system were included.PDP was applied to establish study table and record, and calculate performance of explicit memory and implicit memory. Memory performance was statistically compared with 0, 0 memory was considered to be statistically significant and disappearance, respectively.Sequential method was used for determination.According to explicit memory disappearance or not,target concentration of the next patient was adjusted (increase or decrease).DEX target concentration of the first patient was set to 4 ng?mL-1,and the ratio of target concentration between the adjacent patients was 1.2.If the explicit memory of the former patient disappeared,the target concentration of the next patient was decreased by 1 concentration gradient;if the explicit memory of the former patient did not disappear,the target concentration of the next patient was increased by 1 concentration gradient, and so forth. All the 40 patients were determined.The median effective dose (D1) and 95% confidence interval (CI) of DEX were calculated. Results The ED50 of DEX causing explicit memory disappearance was 5.23 ng?mL-1,and the 95% CI was 4.07-6.39 ng?mL-1. Conclusion In clinical,target concentration of dexmedetomidine hydrochloride 5.23 ng?mL-1 levels for sedation,can cause half of patients’ explicit memory disappear,so as to avoid intraoperative awareness.