title: Dextromethorphan or dextrorphan have a local anesthetic effect on infiltrative cutaneous analgesia in rats.
abstract: BACKGROUND
  Dextromethorphan blocks sodium channels, the site of action of local anesthetics. In this study we evaluated whether dextromethorphan has a local anesthetic effect.
  
  
  METHODS
  We administered dextromethorphan and its active metabolite--dextrorphan, and lidocaine subcutaneously to rats and tested them for cutaneous anesthesia. Drug-drug interactions and systemic safety indices (LD50s/ED50s) were also evaluated.
  
  
  RESULTS
  Dextromethorphan and dextrorphan had a local anesthetic effect after cutaneous infiltration. The ranking of potencies was dextromethorphan > dextrorphan > lidocaine (P < 0.01 for each comparison). A combination of dextromethorphan or dextrorphan with lidocaine produced an additive effect. Dextromethorphan and dextrorphan had 2.4- and 1.9-fold higher system safety indices than did lidocaine.
  
  
  CONCLUSIONS
  Dextromethorphan and dextrorphan were more potent local anesthetics than lidocaine, but with higher systemic safety indices. Coadministration of dextromethorphan or dextrorphan with lidocaine produced an additive effect.
authors: Department of Medical Research, Chi-Mei Medical Center, Tainan, Taiwan.
authors: Yu-Wen
authors: YW
authors: Chen
authors: Koung-Shing
authors: KS
authors: Chu
authors: Ching-Nan
authors: CN
authors: Lin
authors: Jann-Inn
authors: JI
authors: Tzeng
authors: Chin-Chen
authors: CC
authors: Chu
authors: Mao-Tsun
authors: MT
authors: Lin
authors: Jhi-Joung
authors: JJ
authors: Wang
mesh_terms: D000698:Analgesia / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D000818:Animals; D003915:Dextromethorphan / Q000008:administration & dosage*; D003917:Dextrorphan / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D007279:Injections, Subcutaneous; D007928:Lethal Dose 50; D008012:Lidocaine / Q000008:administration & dosage; D008297:Male; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000779:Anesthetics, Local; D003917:Dextrorphan; D003915:Dextromethorphan; D008012:Lidocaine