title: EC(50) of remifentanil to prevent withdrawal movement associated with injection of rocuronium.
abstract: OBJECTIVE
  Various strategies have been studied to reduce the discomfort of rocuronium injection. This study was designed to determine the effect-site target concentration (Ce) of remifentanil at which there was a 50% probability of preventing movement from pain in response to the injection of rocuronium (EC(50)).
  
  
  METHODS
  Anesthesia was induced with a propofol target-controlled infusion (TCI, Marsh model) and remifentanil TCI (Minto model). Effect-site target concentration of propofol was 3 microg/ml. Ce of remifentanil for the first patient started at 2.0 ng/ml. Ce of remifentanil for each subsequent patient was determined by the response of the previous patient by the Dixon up-and-down method with an interval of 0.5 ng/ml. After both drugs reached target concentration, rocuronium 0.8 mg/kg was administered, and the pain response was observed.
  
  
  RESULTS
  The EC(50) of remifentanil was 1.5 +/- 0.45 ng/ml by Dixon's up-and-down method. From probit analysis, the EC(50) of remifentanil was 1.37 ng/ml (95% confidence limits, 0.69-2.15 ng/ml), and the EC(95) was 3.19 ng/ml (95% confidence limits, 2.31-11.24 ng/ml).
  
  
  CONCLUSIONS
  The EC(50) of remifentanil to blunt the withdrawal responses to rocuronium injection was 1.37-1.5 ng/ml during 3 microg/ml propofol TCI anesthesia.
authors.affiliation: Department of Anesthesia and Pain Medicine, School of Medicine, Pusan National University, 1-10 Ami-dong, Seo-gu, Busan, 602-739, Korea.
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Yoon
authors.forename: Hae Kyu
authors.initials: HK
authors.lastname: Kim
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Kwon
authors.forename: Sang Wook
authors.initials: SW
authors.lastname: Shin
authors.forename: Kyung Hoon
authors.initials: KH
authors.lastname: Kim
authors.forename: Won Sung
authors.initials: WS
authors.lastname: Kim
authors.forename: Tae Kyun
authors.initials: TK
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000732:Androstanols / Q000008:administration & dosage* / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000493:pharmacokinetics* / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000187:drug effects* / Q000502:physiology; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage* / Q000009:adverse effects; D010146:Pain / Q000139:chemically induced / Q000517:prevention & control; D010880:Piperidines / Q000493:pharmacokinetics* / Q000494:pharmacology; D012018:Reflex / Q000187:drug effects* / Q000502:physiology; D000077208:Remifentanil; D000077123:Rocuronium; D055815:Young Adult
chemical_list: D000732:Androstanols; D006993:Hypnotics and Sedatives; D003473:Neuromuscular Nondepolarizing Agents; D010880:Piperidines; D000077208:Remifentanil; D000077123:Rocuronium