title: Dexmedetomidine Dose Dependently Enhances the Local Anesthetic Action of Lidocaine in Inferior Alveolar Nerve Block: A Randomized Double-Blind Study.
abstract: OBJECTIVE
  Dexmedetomidine (DEX) dose dependently enhances the local anesthetic action of lidocaine in rats. We hypothesized that the effect might also be dose dependent in humans. We evaluated the effect of various concentrations of DEX with a local anesthetic in humans.
  
  
  METHODS
  Eighteen healthy volunteers were randomly assigned by a computer to receive 1.8 mL of 1 of 4 drug combinations: (1) 1% lidocaine with 2.5 ppm (parts per million) (4.5 μg) DEX, (2) lidocaine with 5.0 ppm (9.0 μg) DEX, (3) lidocaine with 7.5 ppm (13.5μg) DEX, or (4) lidocaine with 1:80,000 (22.5 μg) adrenaline (AD), to produce inferior alveolar nerve block. Pulp latency and lower lip numbness (for assessing onset and duration of anesthesia) were tested, and sedation level, blood pressure, and heart rate were recorded every 5 minutes for 20 minutes, and every 10 minutes from 20 to 60 minutes.
  
  
  RESULTS
  Pulp latency of each tooth increased compared with baseline, from 5 to 15 minutes until 60 minutes. There were no significant intergroup differences at any time point. Anesthesia onset was not different between groups. Anesthesia duration was different between groups (that with DEX 7.5 ppm was significantly longer than that with DEX 2.5 ppm and AD; there was no difference between DEX 2.5 ppm and AD). Blood pressure decreased from baseline in the 5.0 and 7.5 ppm DEX groups at 30 to 60 minutes, although there was no hypotension; moreover, heart rate did not change in any group. Sedation score did not indicate deep sedation in any of the groups.
  
  
  CONCLUSIONS
  Dexmedetomidine dose dependently enhances the local anesthetic action of lidocaine in humans. Dexmedetomidine at 2.5 ppm produces similar enhancement of local anesthesia effect as addition of 1:80,000 AD.
authors.affiliation: From the Department of Dental Anesthesiology, Field of Oral and Maxillofacial Rehabilitation, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Ouchi
authors.forename: Kazuna
authors.initials: K
authors.lastname: Sugiyama
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists / Q000008:administration & dosage* / Q000009:adverse effects; D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000009:adverse effects; D018592:Cross-Over Studies; D003782:Dental Pulp / Q000294:innervation*; D020927:Dexmedetomidine / Q000008:administration & dosage* / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004357:Drug Synergism; D004837:Epinephrine / Q000008:administration & dosage; D005260:Female; D064368:Healthy Volunteers; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007564:Japan; D008012:Lidocaine / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D008340:Mandibular Nerve / Q000187:drug effects*; D009407:Nerve Block / Q000009:adverse effects / Q000379:methods*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects*; D011446:Prospective Studies; D011930:Reaction Time / Q000187:drug effects; D013997:Time Factors; D055815:Young Adult
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D000779:Anesthetics, Local; D020927:Dexmedetomidine; D008012:Lidocaine; D004837:Epinephrine