title: Intradermal sufentanil does not improve lidocaine-induced local anesthesia.
abstract: OBJECTIVE
  Peripheral opioid receptors may result in antinociceptive effects when occupied by opioids. This study examined intradermally injected sufentanil (S), a highly lipid soluble opioid, administered with and without lidocaine (L), in a thermal pain model.
  
  
  METHODS
  Nine volunteers were instructed on the method of magnitude estimation of pain before undergoing baseline testing with seven seconds thermal stimuli between 44 and 52 degrees C, delivered by a contact thermal stimulator at five cutaneous forearm sites. Then, four sites randomly received injections of equal volumes (0.1 mL) of either normal saline (NS), lidocaine 0.5% (L), sufentanil 0.75 microg (S), lidocaine 0.5% plus sufentanil 0.75 microg (L+S), and one site was not injected and served as reference (REF). Testing was repeated at six, 30, 60, 90, 120, and 150 min following injection. The pain elicited by each stimulus was normalized to the subject's response to the 50 degrees C stimulus at the REF site.
  
  
  RESULTS
  Baseline testing showed small (P = ns) differences in pain scores. At six minutes, the lidocaine sites (L, L+S) had pain scores that were mean 83% (range 78-88%) lower than the other sites (P < 0.05), but there was no difference between the L and L+S sites or between the S and NS or REF sites. At 30 and 60 min these pain scores were mean 38% (29-44%) and 20% (8-30%) less than at the REF, NS, and S sites (P = ns). At 90 min and later times, the pain scores had returned to baseline.
  
  
  CONCLUSIONS
  These results suggest that intradermal sufentanil alone has no analgesic effect. Further, in combination with lidocaine, sufentanil does neither potentiate nor prolong the analgesic effect of lidocaine.
authors.affiliation: Departments of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut 06520-8051, USA.
authors.forename: Maximilian W B
authors.initials: MW
authors.lastname: Hartmannsgruber
authors.forename: Peter G
authors.initials: PG
authors.lastname: Atanassoff
authors.forename: Arne
authors.initials: A
authors.lastname: Budde
authors.forename: Sorin J
authors.initials: SJ
authors.lastname: Brull
authors.forename: Zeev N
authors.initials: ZN
authors.lastname: Kain
authors.forename: David G
authors.initials: DG
authors.lastname: Silverman
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000494:pharmacology*; D004357:Drug Synergism; D006358:Hot Temperature; D006801:Humans; D007271:Injections, Intradermal; D008012:Lidocaine / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000187:drug effects*; D017409:Sufentanil / Q000008:administration & dosage / Q000494:pharmacology*; D013696:Temperature
chemical_list: D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D008012:Lidocaine; D017409:Sufentanil