title: A pharmacodynamic evaluation of dexmedetomidine as an additive drug to ropivacaine for peripheral nerve blockade: A randomised, triple-blind, controlled study in volunteers.
abstract: BACKGROUND
  Previous data have indicated the efficacy of dexmedetomidine as an additive to peripheral regional anaesthesia. There are no pharmacodynamic data regarding the addition of dexmedetomidine to local anaesthetics for perineural administration.
  
  
  OBJECTIVE
  The objective of this study is to assess the dose-dependency of dexmedetomidine when injected with ropivacaine for peripheral nerve blockade.
  
  
  METHODS
  A randomised, triple-blind, controlled study in volunteers.
  
  
  METHODS
  Department of Clinical Pharmacology, Medical University of Vienna.
  
  
  METHODS
  Twenty-four volunteers.
  
  
  METHODS
  All volunteers received an ulnar nerve block with 22.5 mg ropivacaine alone (R), or mixed with 50 (RD50), 100 (RD100) or 150 μg (RD150) dexmedetomidine.
  
  
  METHODS
  The primary outcome was the duration of complete sensory block to pinprick and time to complete recovery of pinprick. Secondary outcomes included block success and onset time, motor block, haemodynamic parameters and sedation level.
  
  
  RESULTS
  There was a significant dose-dependent (P < 0.0001) increase in the mean duration (SD) of sensory block with dexmedetomidine: R: 8.7 (1.5) h, RD50: 16.4 (4.0) h, RD100: 20.4 (2.8) h and group RD150: 21.2 (1.7) h. Sedation was also enhanced in a dose-dependent (P < 0.001) manner. Two volunteers each receiving 150 μg dexmedetomidine had postblock paraesthesia for 72 h.
  
  
  CONCLUSIONS
  Dexmedetomidine mixed with ropivacaine produces a dose-dependent prolongation of sensory block and clinically relevant dose-dependent sedation. Dexmedetomidine 100 μg may represent a balance between efficacy and sedation.
authors.affiliation: From the Department of Anaesthesia, Intensive Care Medicine and Pain Therapy (MK, PM, SCK, DM, OK), and Department of Clinical Pharmacology (MK, MZ), Medical University of Vienna, Vienna, Austria.
authors.forename: Maya
authors.initials: M
authors.lastname: Keplinger
authors.forename: Peter
authors.initials: P
authors.lastname: Marhofer
authors.forename: Stephan C
authors.initials: SC
authors.lastname: Kettner
authors.forename: Daniela
authors.initials: D
authors.lastname: Marhofer
authors.forename: Oliver
authors.initials: O
authors.lastname: Kimberger
authors.forename: Markus
authors.initials: M
authors.lastname: Zeitlinger
mesh_terms: D000328:Adult; D000577:Amides / Q000008:administration & dosage*; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage / Q000009:adverse effects; D000779:Anesthetics, Local / Q000008:administration & dosage*; D020927:Dexmedetomidine / Q000008:administration & dosage* / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009407:Nerve Block / Q000379:methods*; D010292:Paresthesia / Q000139:chemically induced; D011446:Prospective Studies; D000077212:Ropivacaine; D013997:Time Factors; D014459:Ulnar Nerve; D055815:Young Adult
chemical_list: D000577:Amides; D018712:Analgesics, Non-Narcotic; D000779:Anesthetics, Local; D020927:Dexmedetomidine; D000077212:Ropivacaine