[Antipruritic effects of pimecrolimus and tacrolimus]

The development of topical calcineurin inhibitors resulted in a significant improvement in the treatment of inflammatory skin diseases such as atopic dermatitis. In addition, an excellent amelioration of pruritus could be observed. Other itchy dermatoses such as chronic irritative hand dermatitis, rosacea, graft-versus-host-disease, renal pruritus, lichen sclerosus, prurigo simplex, prurigo nodularis, scrotal eczema, and inverse psoriasis also have been treated successfully with pimecrolimus and tacrolimus. The antipruritic effect currently is believed to be related to the inhibition of inflammatory cytokines. Furthermore, recent investigations indicate a release of neuropeptides from sensory nerve fibers and degranulation of mast cells mediated by pimecrolimus and tacrolimus. Similar effects have been observed during capsaicin treatment. These findings may provide a possible explanation for initially observed calcineurin inhibitors related side-effects such as burning and pruritus. Moreover, the antipruritic potency may be related to a direct effect on nerve fibers leading to suppression of itch mediated by unknown mechanisms.