The antinociceptive and anti-inflammatory effects of a long-acting depot formulated ketorolac in rats.
BACKGROUND
Currently, no long-acting nonsteroidal anti-inflammatory drug is available clinically for the treatment of long-lasting pain. The aim of the study was to evaluate the antinociceptive and anti-inflammatory effects and duration of action of a novel depot formulation of ketorolac benzyl ester in sesame oil.


METHODS
Two studies in Sprague-Dawley rats were carried out. In study 1, the antinociceptive and anti-inflammatory effects of intramuscular ketorolac tromethamine were evaluated. In study 2, the antinociceptive and anti-inflammatory effects of intramuscular ketorolac benzyl ester were evaluated. The antinociceptive effect was evaluated using the paw pressure test, whereas the anti-inflammatory effect was evaluated by the paw edema test.


RESULTS
Intramuscular ketorolac tromethamine at 24, 80, and 240 micromol/kg (in saline) produced significant antinociceptive and anti-inflammatory effects with duration of action around 6 to 8 h. Ketorolac benzyl ester at a dose of 240 micromol/kg (in oil) produced significant long-acting antinociceptive and anti-inflammatory effects with duration of action of 56 h.


CONCLUSIONS
Intramuscular injection of ketorolac benzyl ester (in sesame oil) in rats produced antinociceptive and anti-inflammatory effects which were 7-fold longer in duration of action than ketorolac tromethamine (in saline).
Tzeng
Jann-Inn
JI
Departments of Anesthesiology and Medical Research, Chi-Mei Medical Center (Yung-Kang and Liou-Ying), Tainan, Taiwan, ROC.
Chu
Chin-Chen
CC
Feng
Ping-Hsun
PH
Hou
Chia-Hui
CH
Shieh
Ja-Ping
JP
Ho
Shung-Tai
ST
Wang
Jhi-Joung
JJ
D000700:Analgesics / Q000008:administration & dosage*; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage*; D002626:Chemistry, Pharmaceutical; D004305:Dose-Response Relationship, Drug; D020910:Ketorolac / Q000008:administration & dosage*; D020911:Ketorolac Tromethamine / Q000008:administration & dosage; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
D000700:Analgesics; D000894:Anti-Inflammatory Agents, Non-Steroidal; D020911:Ketorolac Tromethamine; D020910:Ketorolac