Topical ondansetron attenuates nociceptive and inflammatory effects of intradermal capsaicin in humans

Topical application of the 5-HT3, receptor antagonist ondansetron (50-250 mu g) delivered in a pluronic lecithin organogel vehicle (PLO, 0.5 ml) produced dose-dependent attenuation of nociceptive and inflammatory effects of intradermally injected capsaicin (10 mu g/10 mu l) in humans. Significant, dose-dependent analgesic effects were produced by 100 mu g and 250 mu g doses of ondansetron; these doses also reduced mechanical hyperalgesia produced by capsaicin. However, only 250 mu g dose of ondansetron diminished capsaicin-induced inflammatory flare. (C) 1998 Elsevier Science B.V. All rights reserved.