A novel long-acting analgesic: buprenorphine palmitate in rats.
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.
Que
Jenny
J
Department of Radio-oncology, Chi-Mei Medical Center, Tainan, Taiwan, ROC.
Lin
Li-Ching
LC
Liu
Shynn-Yeu
SY
Chu
Chin-Chen
CC
Liu
Kuo-Sheng
KS
Ho
Shung-Tai
ST
Wang
Jhi-Joung
JJ
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
D000701:Analgesics, Opioid; D010168:Palmitates; D002047:Buprenorphine