title: The effect of intravenous dexmedetomidine premedication on the dose requirement of propofol to induce loss of consciousness in patients receiving alfentanil.
abstract: Dexmedetomidine reduces the dose requirements for opioids and anaesthetic agents. We conducted a single-centre, open-label, noncomparative phase II study of the effect of intravenous dexmedetomidine on the dose requirement of propofol to induce loss of consciousness in 49 ASA I and II patients. The initial dexmedetomidine infusion scheme was reduced twice because of adverse events. Forty patients who received the final infusion scheme were randomly allocated to receive one of five stepped propofol infusions; loss of consciousness was assessed after 21 min. The ED50 for the final infusion rate of propofol to suppress consciousness was 3.45 mg x kg(-1) x h(-1) (95% CL 2.7-4.2): ED95 was 6.68 mg x kg(-1) x h(-1) (95% CL 5.1-19.1), EC50 was 1.69 microg x ml(-1) (95% CL 0.95-2.5) and EC95 was 5.7 microg x ml(-1) (95% CL 3.2 to > 10). Our final dose of dexmedetomidine of 0.63 microg x kg(-1) caused a reduction in the overall concentration and dose of propofol required to produce loss of consciousness, but no significant shift in the dose-response curve compared with other studies.
authors.affiliation: Royal United Hospital Bath, Combe Park, Bath BA1 3NG, UK.
authors.forename: C J
authors.initials: CJ
authors.lastname: Peden
authors.forename: A H
authors.initials: AH
authors.lastname: Cloote
authors.forename: N
authors.initials: N
authors.lastname: Stratford
authors.forename: C
authors.initials: C
authors.lastname: Prys-Roberts
mesh_terms: D000293:Adolescent; D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage* / Q000097:blood; D000328:Adult; D015760:Alfentanil / Q000008:administration & dosage*; D000704:Analysis of Variance; D018686:Anesthetics, Intravenous / Q000008:administration & dosage* / Q000097:blood; D001919:Bradycardia / Q000139:chemically induced; D002851:Chromatography, High Pressure Liquid; D020927:Dexmedetomidine / Q000097:blood / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004837:Epinephrine / Q000097:blood; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage* / Q000097:blood; D009638:Norepinephrine / Q000097:blood; D011229:Preanesthetic Medication; D015742:Propofol / Q000008:administration & dosage* / Q000097:blood; D011863:Radioimmunoassay
chemical_list: D000316:Adrenergic alpha-Agonists; D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D015760:Alfentanil; D020927:Dexmedetomidine; D009638:Norepinephrine; D015742:Propofol; D004837:Epinephrine