title: Effect of dexmedetomidine injected into the oral mucosa in combination with lidocaine on local anesthetic potency in humans: a crossover double-blind study.
abstract: OBJECTIVE
  Recently, attention has been paid to dexmedetomidine, a selective α-2 adrenoceptor agonist, as a possible additive for local anesthesia. However, the effect of locally injected dexmedetomidine on the anesthetic action in humans has not fully been clarified. Thus, the purpose of the present study was to evaluate the effect of dexmedetomidine injected into the oral mucosa in combination with lidocaine on local anesthetic potency in humans.
  
  
  METHODS
  Twenty healthy volunteers were included in the present crossover double-blinded study. Lidocaine solution or lidocaine plus dexmedetomidine solution was submucosally injected into the alveolar mucosa in a crossover and double-blinded manner. The local anesthetic effect of the solutions was evaluated by measuring the current perception threshold (CPT) in the oral mucosa for 120 minutes after injection. Furthermore, the sedation level, blood pressure, and heart rate of the volunteers were evaluated. For statistical analysis, the Wilcoxon signed rank test and 2-way repeated measures analysis of variation were used.
  
  
  RESULTS
  The CPT was increased with the 2 solutions and peaked 10 minutes after injection. CPT values 10 and 20 minutes after injection of lidocaine plus dexmedetomidine solution were considerably higher than those with lidocaine solution. The duration of an important increase in the CPT after injection with lidocaine plus dexmedetomidine solution was longer than that with lidocaine. Furthermore, the area under the time curve of CPT was considerably higher with lidocaine plus dexmedetomidine solution than with lidocaine solution. No volunteer showed a change in sedation level, blood pressure, or heart rate after injection with either test solution throughout the experiment.
  
  
  CONCLUSIONS
  The present study showed that a combination of dexmedetomidine plus lidocaine considerably enhances the local anesthetic potency of lidocaine without any major influences on the cardiovascular system when locally injected into the oral mucosa.
authors.affiliation: Clinical Staff, Department of Dental Anesthesiology, Okayama University Hospital, Okayama, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Yamane
authors.affiliation: Senior Assistant Professor, Department of Dental Anesthesiology, Okayama University Hospital, Okayama, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Higuchi
authors.affiliation: Assistant Professor, Department of Dental Anesthesiology and Special Care Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Tomoyasu
authors.affiliation: Clinical Staff, Department of Dental Anesthesiology, Okayama University Hospital, Okayama, Japan.
authors.forename: Minako
authors.initials: M
authors.lastname: Ishii-Maruhama
authors.affiliation: Associate Professor, Department of Dental Anesthesiology, Okayama University Hospital, Okayama, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Maeda
authors.affiliation: Professor and Chairman, Department of Dental Anesthesiology and Special Care Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan. Electronic address: miyawaki@md.okayama-u.ac.jp.
authors.forename: Takuya
authors.initials: T
authors.lastname: Miyawaki
mesh_terms: D000759:Adjuvants, Anesthesia / Q000008:administration & dosage / Q000627:therapeutic use*; D058647:Adrenergic alpha-2 Receptor Agonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage*; D019540:Area Under Curve; D001794:Blood Pressure / Q000187:drug effects; D003243:Consciousness / Q000187:drug effects; D018592:Cross-Over Studies; D020927:Dexmedetomidine / Q000008:administration & dosage / Q000627:therapeutic use*; D004311:Double-Blind Method; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007267:Injections; D008012:Lidocaine / Q000008:administration & dosage*; D008297:Male; D009061:Mouth Mucosa / Q000187:drug effects*; D017288:Pain Threshold / Q000187:drug effects
chemical_list: D000759:Adjuvants, Anesthesia; D058647:Adrenergic alpha-2 Receptor Agonists; D000779:Anesthetics, Local; D020927:Dexmedetomidine; D008012:Lidocaine