The antinociceptive effect of buprenorphine and its long-acting ester buprenorphine benzoate in rats.
BACKGROUND
A long-acting analgesic is particularly desirable in patients with long-lasting pain. In order to prolong the duration of action of a potent analgesic, buprenorphine, a buprenorphine ester (buprenorphine benzoate) was synthesized in our laboratory. The aim of the study was to evaluate whether the ester form could have a long-lasting effect.


METHODS
Two studies were carried out. In study 1, we evaluated the antinociceptive effect of buprenorphine HCI at dosage of 0.05, 0.1, and 0.6 micromol/kg. In study 2, we evaluated the antinociceptive effect of buprenorphine benzoate at dosage of 0.6 micromol/kg. Male Sprague-Dawley rats (n = 12 in each group of different treatment) were used and the antinociceptive effects of the testing compounds were evaluated using the plantar test (a thermal test).


RESULTS
Intramuscular injection of buprenorphine HCI at dosage of 0.05, 0.1, and 0.6 micromol/kg in rats produced dose-related antinociceptive effects with duration of action of 3, 4, and 4 h, respectively. Intramuscular injection of buprenorphine benzoate at 0.6 micromol/kg produced a duration of action of 48 h.


CONCLUSIONS
Intramuscular injection of buprenorphine benzoate in rats produced a longer duration of action, which is 12-fold longer than that of buprenorphine HCI.
Yang
Cheng
C
Division of Plastic Surgery, Chi-Mei Medical Center, Tainan, Taiwan, ROC.
Lan
Kuo-Mao
KM
Liu
Kuo-Sheng
KS
Chen
Yu-Wen
YW
Tzeng
Jann-Inn
JI
Ho
Shung-Tai
ST
Wang
Jhi-Joung
JJ
D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D002047:Buprenorphine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
D000700:Analgesics; D002047:Buprenorphine