title: A novel long-acting analgesic: buprenorphine palmitate in rats.
abstract: BACKGROUND
  A long-acting analgesic may be particularly desirable in patients with long-lasting pain. In order to provide a long-acting analgesic effect, a novel buprenorphine ester, buprenorphine palmitate, was synthesized in our laboratory. The aim of the study was to evaluate whether the ester had a long-lasting effect.
  
  
  METHODS
  The antinociceptive effects (dose-range studies) of buprenorphine HCl and buprenorphine palmitate were evaluated using the plantar test in Sprague-Dawley rats.
  
  
  RESULTS
  We found that intramuscular injection of buprenorphine HCl 0.05, 0.1 and 1 micromol/kg in rats produced dose-related antinociceptive effects of 2, 3, and 4 h, respectively. Intramuscular injection of buprenorphine palmitate 1, 5, and 10 micromol/kg also produced dose-related antinociceptive effects of 72, 76 and 78 h, respectively. On an equimolar basis of 1 micromol/kg, the durations of action of intramuscular buprenorphine HCl and buprenorphine palmitate were 4 and 72 h, respectively.
  
  
  CONCLUSIONS
  Intramuscular injection of buprenorphine palmitate in rats produced a long-lasting antinociceptive effect which was much longer (18-fold) than did intramuscular buprenorphine HCl.
authors.affiliation: Department of Radio-oncology, Chi-Mei Medical Center, Tainan, Taiwan, ROC.
authors.forename: Jenny
authors.initials: J
authors.lastname: Que
authors.forename: Li-Ching
authors.initials: LC
authors.lastname: Lin
authors.forename: Shynn-Yeu
authors.initials: SY
authors.lastname: Liu
authors.forename: Chin-Chen
authors.initials: CC
authors.lastname: Chu
authors.forename: Kuo-Sheng
authors.initials: KS
authors.lastname: Liu
authors.forename: Shung-Tai
authors.initials: ST
authors.lastname: Ho
authors.forename: Jhi-Joung
authors.initials: JJ
authors.lastname: Wang
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D002047:Buprenorphine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D007273:Injections, Intramuscular; D008297:Male; D010168:Palmitates / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D010168:Palmitates; D002047:Buprenorphine