Adv Exp Med Biol
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In summary, therapy with opioids is an exciting new development for arthritis especially since there is the potential for fewer side effects from molecules which act outside the CNS. We found kappa-opioid drugs to be powerfully anti-inflammatory, reducing disease severity by as much as 80%; attenuating arthritis in a dose-dependent, stereoselective, antagonist-reversible manner. By contrast opioids acting at other receptors were only therapeutic at near toxic doses. ⋯ The increased potency of kappa-opioids in females is likely to be a significant advantage for treatment of inflammatory disease with these agents. Thus our work supports the findings of Stein's group, that opioids do indeed have powerful actions in the periphery via specific receptors at that site. Peripherally acting opioids may prove to be a potent new treatment for rheumatoid arthritis sufferers in the future.