Bullous pemphigoid is the most frequent autoimmune bullous disease and mainly
affects elderly individuals. Increase in incidence rates in the past decades has
been attributed to population aging, drug-induced cases and improvement in the
diagnosis of the nonbullous presentations of the disease. A dysregulated T cell
immune response and synthesis of IgG and IgE autoantibodies against
hemidesmosomal proteins (BP180 and BP230) lead to neutrophil chemotaxis and
degradation of the basement membrane zone. Bullous pemphigoid classically
manifests with tense blisters over urticarial plaques on the trunk and
extremities accompanied by intense pruritus. Mucosal involvement is rarely
reported. Diagnosis relies on (1) the histopathological evaluation demonstrating
eosinophilic spongiosis or a subepidermal detachment with eosinophils; (2) the
detection of IgG and/or C3 deposition at the basement membrane zone using direct
or indirect immunofluorescence assays; and (3) quantification of circulating
autoantibodies against BP180 and/or BP230 using ELISA. Bullous pemphigoid is
often associated with multiple comorbidities in elderly individuals, especially
neurological disorders and increased thrombotic risk, reaching a 1-year
mortality rate of 23%. Treatment has to be tailored according to the patient's
clinical conditions and disease severity. High potency topical steroids and
systemic steroids are the current mainstay of therapy. Recent randomized
controlled studies have demonstrated the benefit and safety of adjuvant
treatment with doxycycline, dapsone and immunosuppressants aiming a reduction in
the cumulative steroid dose and mortality.
Basophils of patients with CIU showed an activated profile, possibly due to an in vivo priming. Functionally, basophils have high responsiveness to IL-3 stimulation, thereby suggesting that defects in the signal transduction pathway after IgE cross-linking stimuli are recoverable in subjects with chronic urticaria.
Drugs with antihistamine action are the most commonly prescribed medication in daily dermatologic practice, both to adults and children. This article addresses new concepts of the role of histamine receptors (H1 receptors) and discusses the anti-inflammatory effects of these drugs. Second generation antihistamines differs from first generation because of their high specificity and affinity for peripheral H1-receptors. Second generation antihistamines are also less likely to produce sedation because they have less effect on the central nervous system. Although the efficacy of the various H1-antihistamines in the treatment of allergic patients is similar, even when comparing first-and second-generation drugs, these drugs are still very different in terms of their chemical structure, pharmacology and toxic properties. Consequently, knowledge of their pharmacokinetic and pharmacodynamic characteristics is essential for a better medical care, especially that offered to pregnant women, children, the elderly, and patients with comorbidities. Keywords: Histamine; Histamine H1 receptors antagonists; Histamine receptors; Histamine release; Histamine H1 antagonists, non-sedating; Receptors, histamine H1Resumo: As drogas com ação anti-histamínica estão entre as medicações mais comumente prescritas na prática dermatológica diária, tanto em adultos como em crianças. Este artigo aborda os novos conceitos da função dos receptores de histamina (receptores H1) e discute os efeitos anti-inflamatórios dessas drogas. A segunda geração de anti-histamínicos difere da primeira geração devido a sua elevada especificidade e afinidade pelos receptores H1 periféricos e devido a seu menor efeito no sistema nervoso central, tendo como resultado menores efeitos sedativos. Embora a eficácia dos diferentes anti-histamínicos H1 (anti-H1) no tratamento de doentes alérgicos seja similar, mesmo quando se comparam anti-H1 de primeira e de segunda geração, eles são muito diferentes em termos de estrutura química, farmacologia e propriedades tóxicas. Consequentemente o conhecimento de suas características farmacocinéticas e farmacodinâmicas é importante para a melhor prática médica, especialmente em gestantes, crianças, idosos e doentes com comorbidades. Palavras-chave: Antagonistas da histamina H1 não sedativos; Antagonistas dos receptores H1 de histamina; Histamina; Liberação de histamina; Receptores de histamina; Receptores de histamina H1
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