There exists a multitude of medical conditions that cause intractable itch, or pruritus. The successful management of this symptom depends explicitly on establishing the underlying cause. Studies have shown that drugs not traditionally used in the treatment of cutaneous disorders, such as opiate receptor antagonists, antidepressants, and antiepileptics, can provide symptomatic relief of intractable itch. These novel antipruritic agents will be explored in this review. (+info)
Effects of topical application of tacrolimus on acute itch-associated responses in mice.
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Using mice, we examined whether the topical application of tacrolimus would produce an acute anti-pruritic effect. An itch-related response, scratching, was elicited by intradermal injections of mosquito allergen (10 microg/site) in sensitized mice and SLIGRL-NH2 (protease-activated receptor-2 agonist, 50 nmol/site), histamine (100 nmol/site), serotonin (100 nmol/site) and substance P (100 nmol/site) in naive ones. Topical application of 1%, but neither 0.1% nor 0.3%, tacrolimus to the skin 1 h before injection inhibited scratching induced by mosquito allergen and SLIGRL-NH2, without effects on scratching induced by histamine, serotonin, and substance P. Topical tacrolimus also inhibited licking induced by an intraplantar injection of capsaicin (0.1 microg/site). These results suggest that topical tacrolimus exerts acute inhibitory effects on allergic and protease-activated receptor-2-mediated itching. Though precise mechanisms remain unclear, the action on sensory neurons expressing protease-activated receptor-2 and transient receptor potential vanilloid-1 capsaicin receptor may be involved in the inhibitory effects of tacrolimus. (+info)
Evidence for the role of neurogenic inflammation components in trypsin-elicited scratching behaviour in mice.
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