Itch, a complex symptom: topical approach
A review on topical products and cosmetic actives for the treatment of itch. Part 2
Pruritus, or itch, is an unpleasant sensation provoking the desire to scratch, it is a major symptom in numerous dermatological and systemic diseases and can have a dramatic impact on the quality of life. The ultimate determination of the cause of pruritus remains a challenge for any physician: every effort must be made to identify primary and secondary causes of the disorder, and this requires a meticulous history-including medicaments’ intake that can elicit pruritus- and physical examination. The pathogenesis of itch is diverse and involves a complex network of cutaneous and neuronal cells, thus anti-pruritic therapy is often directed against a variety of targets, including the epidermal barrier, immune system, or the nervous system. Topical therapy is the mainstay of dermatologic management of acute or localized itch or in patients with contraindications to systemic therapies. This review will summarize current topical therapies to treat pruritus.
THERAPEUTIC APPROACH: TOPICAL ACTIVES
The current guidelines for the treatment of pruritus recommend a step-by-step treatment procedure, tailored to the severity of symptoms, accompanying diseases, patient age, comedications, and the severity of lesions due to scratching (46). Many patients require combination of systemic and topical therapies. The complexity of interactions between the central and peripheral nervous system and the skin in generating this symptom has delineated a broad spectrum of molecular targets into focus which, when successfully exploited, could serve to treat the itch perception. Therapeutical modalities such as INF γ, TRPV1 receptor antagonists/or agonists, μ-opiate receptor antagonists, κ-opioid receptor agonists, PAR2 receptor antagonists, histamine-3 receptor or histamine-4 receptor targeting molecules, cannabinoid agonists, nerve-growth factor or nerve-growth factor receptor antagonists, neurokinin-1 receptor antagonists, GRPR antagonists, certain prostaglandin and leukotriene antagonists appear to be promising new approaches for the therapy of itch (molecular targets of itch treatment are fully exposed in Table 2). If appr ...