Antinociceptive and anti-inflammatory activity of DW-1021, the ionic complex of pelubiprofen and tramadol, in rodents

Although drugs such as acetaminophen, opioids, and nonsteroidal anti-inflammatory drugs (NSAIDs), are commonly used for pain management, the side effects of these drugs such as hepatotoxicity, nephrotoxicity, nausea, and vomiting, can not be neglected. Therefore, combinations of analgesics with different mechanisms raise the possibility of developing novel analgesics. Therefore, the aim of the present study was to evaluate whether DW-1021, the ionic complex of pelubiprofen (NSAID) and tramadol (opioid), has synergic antinociceptive and anti-inflammatory effects in nociceptive as well as inflammation-induced nociceptive models compared to pelubiprofen- or tramadol-only administration. Strong synergistic antinociceptive efficacy of DW-1021 was observed in the mouse writhing test and von Frey paw withdrawal threshold test in the carrageenan-induced rats. The hot plate test in mice and the Randall-Selitto mechanical paw pressure test in carrageenan-induced rats revealed that DW-1021 had a preferable effect on relieving pain to pelubiprofen, but not as much as tramadol. In the carrageenan-induced rats, DW-1021 had a more potent effect on reducing paw inflammation (paw volume, width, and thickness) via the suppression of PGE₂ production than tramadol, but less than that of pelubiprofen. Taken together, our results suggest that the administration of DW-1021, a combination of pelubiprofen and tramadol, exerted a potent effect and can be used as a potential therapeutic agent for relieving pain and inflammation.