Treatment of itching in atopic eczema with antihistamines with a low sedative profile

European guideline (EuroGuiDerm) on atopic eczema - part II: non-systemic treatments and treatment recommendations for special AE patient populations

The evidence- and consensus-based guideline on atopic eczema was developed in accordance with the EuroGuiDerm Guideline and Consensus Statement Development Manual. Four consensus conferences were held between December 2020 and July 2021. Twenty-nine experts (including clinicians and patient representatives) from 12 European countries participated. This second part of the guideline includes recommendations and detailed information on basic therapy with emollients and moisturizers, topical anti-inflammatory treatment, antimicrobial and antipruritic treatment and UV phototherapy. Furthermore, this part of the guideline covers techniques for avoiding provocation factors, as well as dietary interventions, immunotherapy, complementary medicine and educational interventions for patients with atopic eczema and deals with occupational and psychodermatological aspects of the disease. It also contains guidance on treatment for paediatric and adolescent patients and pregnant or breastfeeding women, as well as considerations for patients who want to have a child. A chapter on the patient perspective is also provided. The first part of the guideline, published separately, contains recommendations and guidance on systemic treatment with conventional immunosuppressive drugs, biologics and janus kinase (JAK) inhibitors, as well as information on the scope and purpose of the guideline, and a section on guideline methodology.

Clinical practice guidelines for the management of atopic dermatitis 2018

Atopic dermatitis (AD) is a disease characterized by relapsing eczema with pruritus as a primary lesion. The current strategies to treat AD in Japan from the perspective of evidence-based medicine consist of three primary measures: (i) the use of topical corticosteroids and tacrolimus ointment as the main treatment for the inflammation; (ii) topical application of emollients to treat the cutaneous barrier dysfunction; and (iii) avoidance of apparent exacerbating factors, psychological counseling and advice about daily life. The guidelines present recommendations to review clinical research articles, evaluate the balance between the advantages and disadvantages of medical activities, and optimize medical activity-related patient outcomes with respect to several important points requiring decision-making in clinical practice.

Oral H1 antihistamines as 'add-on' therapy to topical treatment for eczema

BACKGROUND

The symptoms of eczema can lead to sleeplessness and fatigue and may have a substantial impact on quality of life. Use of oral H1 antihistamines (H1 AH) as adjuvant therapy alongside topical agents is based on the idea that combining the anti-inflammatory effects of topical treatments with the blocking action of histamine on its receptors in the skin by H1 AH (to reduce the principal symptom of itch) might magnify or intensify the effect of treatment. Also, it would be unethical to compare oral H1 AH alone versus no treatment, as topical treatment is the standard management for this condition.

OBJECTIVES

To assess the effects of oral H1 antihistamines as 'add-on' therapy to topical treatment in adults and children with eczema.

SEARCH METHODS

We searched the following databases up to May 2018: the Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase, and the GREAT database (Global Resource of EczemA Trials; from inception). We searched five trials registers and checked the reference lists of included and excluded studies for further references to relevant randomised controlled trials (RCTs). We also searched the abstracts of four conference proceedings held between 2000 and 2018.

SELECTION CRITERIA

We sought RCTs assessing oral H1 AH as 'add-on' therapy to topical treatment for people with eczema compared with topical treatment plus placebo or no additional treatment as add-on therapy.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodological procedures. Primary outcome measures were 'Mean change in patient-assessed symptoms of eczema' and 'Proportion of participants reporting adverse effects and serious adverse events'. Secondary outcomes were 'Mean change in physician-assessed clinical signs', 'Mean change in quality of life', and 'Number of eczema flares'.

MAIN RESULTS

We included 25 studies (3285 randomised participants). Seventeen studies included 1344 adults, and eight studies included 1941 children. Most studies failed to report eczema severity at baseline, but they were conducted in secondary care settings, so it is likely that they recruited patients with more severe cases of eczema. Trial duration was between three days and 18 months. Researchers studied 13 different H1 AH treatments. We could not undertake pooling because of the high level of diversity across studies in terms of duration and dose of intervention, concomitant topical therapy, and outcome assessment. Risk of bias was generally unclear, but five studies had high risk of bias in one domain (attrition, selection, or reporting bias). Only one study measured quality of life, but these results were insufficient for statistical analysis.Although this review assessed 17 comparisons, we summarise here the results of three key comparisons in this review.Cetirizine versus placeboOne study compared cetirizine 0.5 mg/kg/d against placebo over 18 months in 795 children. Study authors did not report patient-assessed symptoms of eczema separately for pruritus. Cetirizine is probably associated with fewer adverse events (mainly mild) (risk ratio (RR) 0.68, 95% confidence interval (CI) 0.46 to 1.01) and the need for slightly less additional H1 AH use as an indication of eczema flare rate (P = 0.035; no further numerical data given). Physician-assessed clinical signs (SCORing Atopic Dermatitis index (SCORAD)) were reduced in both groups, but the difference between groups was reported as non-significant (no P value given). Evidence for this comparison was of moderate quality.One study assessed cetirizine 10 mg/d against placebo over four weeks in 84 adults. Results show no evidence of differences between groups in patient-assessed symptoms of eczema (pruritus measured as part of SCORAD; no numerical data given), numbers of adverse events (RR 1.11, 95% CI 0.50 to 2.45; mainly sedation, other skin-related problems, respiratory symptoms, or headache), or physician-assessed changes in clinical signs, amount of local rescue therapy required, or number of applications as an indicator of eczema flares (no numerical data reported). Evidence for this comparison was of low quality.Fexofenadine versus placeboCompared with placebo, fexofenadine 120 mg/d taken in adults over one week (one study) probably leads to a small reduction in patient-assessed symptoms of pruritus on a scale of 0 to 8 (mean difference (MD) -0.25, 95% CI -0.43 to -0.07; n = 400) and a greater reduction in the ratio of physician-assessed pruritus area to whole body surface area (P = 0.007; no further numerical data given); however, these reductions may not be clinically meaningful. Results suggest probably little or no difference in adverse events (mostly somnolence and headache) (RR 1.05, 95% CI 0.74 to 1.50; n = 411) nor in the amount of 0.1% hydrocortisone butyrate used (co-intervention in both groups) as an indicator of eczema flare, but no numerical data were given. Evidence for this comparison was of moderate quality.Loratadine versus placeboA study of 28 adults compared loratadine 10 mg/d taken over 4 weeks versus placebo. Researchers found no evidence of differences between groups in patient-assessed pruritus, measured by a 100-point visual analogue scale (MD -2.30, 95% CI -20.27 to 15.67); reduction in physician-assessed clinical signs (SCORAD) (MD -4.10, 95% CI -13.22 to 5.02); or adverse events. Study authors reported only one side effect (folliculitis with placebo) (RR 0.25, 95% CI 0.01 to 5.76). Evidence for this comparison was of low quality. Number of eczema flares was not measured for this comparison.

AUTHORS' CONCLUSIONS

Based on the main comparisons, we did not find consistent evidence that H1 AH treatments are effective as 'add-on' therapy for eczema when compared to placebo; evidence for this comparison was of low and moderate quality. However, fexofenadine probably leads to a small improvement in patient-assessed pruritus, with probably no significant difference in the amount of treatment used to prevent eczema flares. Cetirizine was no better than placebo in terms of physician-assessed clinical signs nor patient-assessed symptoms, and we found no evidence that loratadine was more beneficial than placebo, although all interventions seem safe.The quality of evidence was limited because of poor study design and imprecise results. Future researchers should clearly define the condition (course and severity) and clearly report their methods, especially participant selection and randomisation; baseline characteristics; and outcomes (based on the Harmonising Outcome Measures in Eczema initiative).

Consensus-based European guidelines for treatment of atopic eczema (atopic dermatitis) in adults and children: part II

This guideline was developed as a joint interdisciplinary European project, including physicians from all relevant disciplines as well as patients. It is a consensus-based guideline, taking available evidence from other guidelines, systematic reviews and published studies into account. This second part of the guideline covers antimicrobial therapy, systemic treatment, allergen-specific immunotherapy, complementary medicine, psychosomatic counselling and educational interventions, whereas the first part covers methods, patient perspective, general measures and avoidance strategies, basic emollient treatment and bathing, dietary intervention, topical anti-inflammatory therapy, phototherapy and antipruritic therapy. Management of AE must consider the individual clinical variability of the disease. Systemic immunosuppressive treatment with cyclosporine, methotrexate, azathioprine and mycophenolic acid is established option for severe refractory cases, and widely available. Biologicals targeting the T helper 2 pathway such as dupilumab may be a safe and effective, disease-modifying alternative when available. Oral drugs such as JAK inhibitors and histamine 4 receptor antagonists are in development. Microbial colonization and superinfection may cause disease exacerbation and can require additional antimicrobial treatment. Allergen-specific immunotherapy with aeroallergens may be considered in selected cases. Psychosomatic counselling is recommended especially in stress-induced exacerbations. Therapeutic patient education ('Eczema school') is recommended for children and adult patients. General measures, basic emollient treatment, bathing, dietary intervention, topical anti-inflammatory therapy, phototherapy and antipruritic therapy have been addressed in the first part of the guideline.

Consensus-based European guidelines for treatment of atopic eczema (atopic dermatitis) in adults and children: part I

This guideline was developed as a joint interdisciplinary European project, including physicians from all relevant disciplines as well as patients. It is a consensus-based guideline, taking available evidence from other guidelines, systematic reviews and published studies into account. This first part of the guideline covers methods, patient perspective, general measures and avoidance strategies, basic emollient treatment and bathing, dietary intervention, topical anti-inflammatory therapy, phototherapy and antipruritic therapy, whereas the second part covers antimicrobial therapy, systemic treatment, allergen-specific immunotherapy, complementary medicine, psychosomatic counselling and educational interventions. Management of AE must consider the individual clinical variability of the disease; highly standardized treatment rules are not recommended. Basic therapy is focused on treatment of disturbed barrier function by hydrating and lubricating topical treatment, besides further avoidance of specific and unspecific provocation factors. Topical anti-inflammatory treatment based on glucocorticosteroids and calcineurin inhibitors is used for flare management and for proactive therapy for long-term control. Topical corticosteroids remain the mainstay of therapy, whereas tacrolimus and pimecrolimus are preferred in sensitive skin areas and for long-term use. Topical phosphodiesterase inhibitors may be a treatment alternative when available. Adjuvant therapy includes UV irradiation, preferably with UVB 311 nm or UVA1. Pruritus is targeted with the majority of the recommended therapies, but some patients may need additional antipruritic therapy. Antimicrobial therapy, systemic anti-inflammatory treatment, immunotherapy, complementary medicine and educational intervention will be addressed in part II of the guideline.

Antihistamines in the Treatment of Atopic Dermatitis

Background:

Atopic dermatitis (AD) is an inflammatory skin disorder that is exceedingly challenging to treat. A prominent feature of AD is chronic pruritus. Early evidence suggested that pruritus in AD was partially due to mast cell release of histamine. Conversely, recent studies do not validate the role of histamine in the pathogenesis of pruritus. Conventional management continues to include the wide use of antihistamines to treat the persistent itch, however, there is an urgent need for therapy which will reduce the severity of pruritus for these patients.

Objective:

To review the evidence in the literature for the use of antihistamines in the treatment of atopic dermatitis.

Methods:

A MEDLINE search (1966–2002) was performed to obtain studies examining the use of antihistamines in the treatment of atopic dermatitis. Search terms included: atopic dermatitis; eczema; antihistamines; azatadine; brompheniramine; cetirizine; chlorpheniramine; clemastine; cyclizine; cyproheptadine; desloratadine; diphenhydramine; fexofenadine; hydroxyzine; loratadine; meclizine; promethazine; trimeprazine. Further references were gathered from these publications.

Results:

Historically, antihistamines have been used in the treatment of AD. However, this review shows that the evidence for its use is inconclusive. At present, several antihistamines continue to provide relief of pruritus by central sedation, and they can also be used therapeutically for concomitant allergic conditions associated with AD. More clinical trials examining the therapeutic efficacy of antihistamines, especially with the newer nonsedating antihistamines, are necessary to elucidate their role in the treatment of AD.

Conclusion:

Dermatologists require additional evidence regarding the efficacy of antihistamines and their mechanism of action in the treatment of AD to enhance patient care.

Treatment of Atopic Dermatitis From the Perspective of Traditional Persian Medicine: Presentation of a Novel Therapeutic Approach

There is a strong current trend for using complementary and alternative medications to treat atopic dermatitis. Atopic dermatitis is a common, chronic, pruritic, and inflammatory skin disease. It can have a profound, negative effect on patients' quality of life. Mild cases of atopic dermatitis can be controlled by the application of moisturizers and topical corticosteroids. However, in severe cases, application of immunosuppressive medication is unavoidable but it can have adverse effects. In traditional Persian medicine, diseases similar to resistant atopic dermatitis are treated with whey in combination with decoction of field dodder. Both whey and field dodder have anti-inflammatory properties. Consumption of whey can also aid skin repair, mitigate pruritus, and help combat the high level of stress experienced by patients. Therefore, it is hypothesized that consumption of traditional medicinal treatment of whey with decoction of field dodder can be applied as a complementary treatment for atopic dermatitis.

Oral H1 antihistamines as monotherapy for eczema

BACKGROUND

Eczema is a common skin disease in many countries, and although the majority of cases of eczema occur before the age of five years and often resolve during childhood or adolescence, it can also persist into adulthood. Itch is the most important aspect of eczema, often impacting significantly on the quality of life of an affected individual.

OBJECTIVES

To assess the effects of oral antihistamines (H1 antagonists) as monotherapy in children and adults with eczema.

SEARCH METHODS

We searched the following databases up to March 2012: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library (2012, Issue 3), MEDLINE (from 1946), EMBASE (from 1974), and LILACS (from 1982). We examined the reference lists of excluded studies in order to identify further references to relevant trials. We searched trials registers for ongoing and unpublished trials. We also handsearched the abstracts of the International Research Workshops on eczema, as well as the conference proceedings of the European Academy of Dermatology and Venereology (EADV) and the European Academy of Allergology and Clinical Immunology (EAACI), from 2000 to 2011.

SELECTION CRITERIA

We sought to include randomised controlled trials that assessed the effects and safety of oral H1 antihistamines as monotherapy in children and adults with eczema. We excluded studies that compared an antihistamine versus another antihistamine and had no placebo control arm. We also excluded topical antihistamines and oral H1 antihistamines as 'add-on' therapy and studies using any concomitant therapy other than emollients or moisturisers, principally because some of these forms of concomitant therapy may be considered treatment modifiers in assessments of the effects of antihistamines on eczema.

DATA COLLECTION AND ANALYSIS

Our search retrieved 409 references to studies. Based on assessments of their titles, abstracts, or both, we excluded all except 36 of these studies. After evaluation of the full text of each report, we excluded a further 35 studies, and 1 study is awaiting classification pending a response from the trial investigators.

MAIN RESULTS

No randomised controlled trials met our inclusion criteria.

AUTHORS' CONCLUSIONS

There is currently no high-level evidence to support or refute the efficacy or safety of oral H1 antihistamines used as monotherapy for eczema. Because most of the studies allowed the use of concomitant medications and involved multi-therapeutic approaches, meaningful assessments of the individual effects of oral H1 antihistamines on eczema were not feasible. Although well-designed randomised controlled trials excluding concomitant medications appear to be needed, consideration should be given to the potential ethical issues raised with the use of antihistamines as monotherapy for the management of eczema by withholding the use of rescue or additional therapies. A further systematic review of studies in which concomitant therapies were permitted might be of value in determining the potential benefits of oral H1 antihistamines as add-on therapy.

Oral H1 antihistamines as monotherapy for eczema

BACKGROUND

Eczema is a common skin disease in many countries, and although the majority of cases of eczema occur before the age of five years and often resolve during childhood or adolescence, it can also persist into adulthood. Itch is the most important aspect of eczema, often impacting significantly on the quality of life of an affected individual.

OBJECTIVES

To assess the effects of oral antihistamines (H1 antagonists) as monotherapy in children and adults with eczema.

SEARCH METHODS

We searched the following databases up to March 2012: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library (2012, Issue 3), MEDLINE (from 1946), EMBASE (from 1974), and LILACS (from 1982). We examined the reference lists of excluded studies in order to identify further references to relevant trials. We searched trials registers for ongoing and unpublished trials. We also handsearched the abstracts of the International Research Workshops on eczema, as well as the conference proceedings of the European Academy of Dermatology and Venereology (EADV) and the European Academy of Allergology and Clinical Immunology (EAACI), from 2000 to 2011.

SELECTION CRITERIA

We sought to include randomised controlled trials that assessed the effects and safety of oral H1 antihistamines as monotherapy in children and adults with eczema. We excluded studies that compared an antihistamine versus another antihistamine and had no placebo control arm. We also excluded topical antihistamines and oral H1 antihistamines as 'add-on' therapy and studies using any concomitant therapy other than emollients or moisturisers, principally because some of these forms of concomitant therapy may be considered treatment modifiers in assessments of the effects of antihistamines on eczema.

DATA COLLECTION AND ANALYSIS

Our search retrieved 409 references to studies. Based on assessments of their titles, abstracts, or both, we excluded all except 36 of these studies. After evaluation of the full text of each report, we excluded a further 35 studies, and 1 study is awaiting classification pending a response from the trial investigators.

MAIN RESULTS

No randomised controlled trials met our inclusion criteria.

AUTHORS' CONCLUSIONS

There is currently no high-level evidence to support or refute the efficacy or safety of oral H1 antihistamines used as monotherapy for eczema. Because most of the studies allowed the use of concomitant medications and involved multi-therapeutic approaches, meaningful assessments of the individual effects of oral H1 antihistamines on eczema were not feasible. Although well-designed randomised controlled trials excluding concomitant medications appear to be needed, consideration should be given to the potential ethical issues raised with the use of antihistamines as monotherapy for the management of eczema by withholding the use of rescue or additional therapies. A further systematic review of studies in which concomitant therapies were permitted might be of value in determining the potential benefits of oral H1 antihistamines as add-on therapy.

Guidelines for treatment of atopic eczema (atopic dermatitis) part I

The existing evidence for treatment of atopic eczema (atopic dermatitis, AE) is evaluated using the national standard Appraisal of Guidelines Research and Evaluation. The consensus process consisted of a nominal group process and a DELPHI procedure. Management of AE must consider the individual symptomatic variability of the disease. Basic therapy is focused on hydrating topical treatment, and avoidance of specific and unspecific provocation factors. Anti-inflammatory treatment based on topical glucocorticosteroids and topical calcineurin inhibitors (TCI) is used for exacerbation management and more recently for proactive therapy in selected cases. Topical corticosteroids remain the mainstay of therapy, but the TCI tacrolimus and pimecrolimus are preferred in certain locations. Systemic immune-suppressive treatment is an option for severe refractory cases. Microbial colonization and superinfection may induce disease exacerbation and can justify additional antimicrobial treatment. Adjuvant therapy includes UV irradiation preferably with UVA1 wavelength or UVB 311 nm. Dietary recommendations should be specific and given only in diagnosed individual food allergy. Allergen-specific immunotherapy to aeroallergens may be useful in selected cases. Stress-induced exacerbations may make psychosomatic counselling recommendable. 'Eczema school' educational programs have been proven to be helpful. Pruritus is targeted with the majority of the recommended therapies, but some patients need additional antipruritic therapies.

Atopic dermatitis and allergic rhinitis--do co-effects in therapy exist?

Atopic dermatitis and allergic rhinitis frequently appear together in the same patients. The pathogenesis of both disorders is complex and still incompletely understood. Nevertheless, pathophysiological overlaps suggest the existence of potential therapeutic co-effects. While data pointing towards a positive effect of allergen elimination for both diseases is still limited, there is now increasing evidence showing beneficial effects of specific immunotherapy in patients suffering from atopic dermatitis and additional type I allergies. H(1)-antihistamines were also found to exert moderate positive effects on the symptoms of atopic dermatitis in single studies. In summary, a limited therapeutic co-effect of the above mentioned treatment options can be expected in case of the parallel existence of atopic dermatitis and allergic rhinitis in the same patient. More studies on this issue during the next years are desirable. In addition, a better understanding of the pathophysiology should have a positive impact on the treatment of atopic manifestations such as atopic dermatitis and allergic rhinitis.

Pathophysiology and therapy of pruritus in allergic and atopic diseases

Pruritus (itch) is a major characteristic and one of the most debilitating symptoms in allergic and atopic diseases and the diagnostic hallmark of atopic dermatitis. Pruritus is regularly defined as an unpleasant sensation provoking the desire to scratch. Although we achieved rather good knowledge about certain inducers of itch such as neuropeptides, amines, mu-opioids, cytokines and proteases, for example, less is known about the pathophysiological specifities among the different diseases, and the therapeutic consequences which may derive thereoff. This review dissects the role of mediators, receptors and itch inhibitors on peripheral nerve endings, dorsal root ganglia, the spinal cord and the CNS leading to the amplification or - vice versa - suppression of pruritus. As the treatment of pruritus in allergic and atopic skin disease is still not satisfactory, knowing these pathways and mechanisms may lead to novel therapeutic approaches against this frequently encountered skin symptom.

The role of histamine H1 and H4 receptors in allergic inflammation: the search for new antihistamines

Histamine has a key role in allergic inflammatory conditions. The inflammatory responses resulting from the liberation of histamine have long been thought to be mediated by the histamine H1 receptor, and H1-receptor antagonists--commonly known as antihistamines--have been used to treat allergies for many years. However, the importance of histamine in the pathology of conditions such as asthma and chronic pruritus may have been underestimated. Here, we review accumulating evidence suggesting that histamine indeed has roles in inflammation and immune function modulation in such diseases. In particular, the discovery of a fourth histamine receptor (H4) and its expression on numerous immune and inflammatory cells has prompted a re-evaluation of the actions of histamine, suggesting a new potential for H4-receptor antagonists and a possible synergy between H1 and H4-receptor antagonists in targeting various inflammatory conditions.

Atopic dermatitis: understanding the disease and its management

OBJECTIVE

Atopic dermatitis (AD) is a common, chronic, inflammatory skin disease that can significantly reduce the quality of life of not only patients but also entire families. This review will focus on the currently available non-pharmacologic and pharmacologic treatments for the control and management of AD.

RESEARCH DESIGN AND METHODS

A review of English-language articles from January 1953 to May 2006 was performed within the MEDLINE database. Search terms included, but were not limited to, atopic dermatitis, topical corticosteroids, and topical calcineurin inhibitors. Studies evaluating the diagnosis, physical and psychological burden, and underlying pathophysiology of AD were included. Particular focus was placed on literature presenting key safety and efficacy data from clinical trials involving AD treatment.

RESULTS

Although good skin care and trigger avoidance are fundamental to AD management, most patients also require pharmacologic intervention. Topical therapies comprise the foundation of AD treatment. In particular, topical corticosteroids have been a mainstay in AD treatment for several decades and the newer topical calcineurin inhibitors have become a valuable addition to the therapeutic armamentarium. TCIs are a safe and effective AD treatment; they limit the number of disease flares, extend the time between flares, and provide a steroid-sparing option that may be of particular benefit in the pediatric population. The use of more potent therapies, such as systemic (oral/injected) agents or phototherapy, is typically limited to the treatment of severe, refractory disease. Additionally, owing to the increased risk for bacterial, viral, and fungal infections in patients with AD, topical or systemic antimicrobials are an important component of treatment.

LIMITATIONS

Case reports and small-scale studies were typically not included in this analysis and owing to the limited number of trials evaluating TCSs, consensus statements and comprehensive review articles were used to obtain information pertaining to the use of this treatment in AD.

CONCLUSIONS

AD is a common, chronic disease requiring a long-term management strategy that incorporates preventive measures and a multipronged treatment approach.

Spontaneous scratching behaviour in DS-Nh mice as a possible model for pruritus in atopic dermatitis

Itching is one of the major clinical symptoms in atopic dermatitis (AD) and complicates the management of this pathological condition. An animal model of AD-like pruritus would contribute to a better understanding of AD and could lead to the development of safe and effective antipruritic agents. DS non-hair (DS-Nh) mice raised under conventional conditions spontaneously develop pruritus, which is associated with a dermatitis similar to human AD. There is a significant positive correlation between disease severity and the period of scratching behaviour in DS-Nh mice. In the present study, we found that levels of histamine and nerve growth factor (NGF) in serum and/or skin tissue were higher in DS-Nh mice with AD-like dermatitis than in age-matched mice without dermatitis. The histopathological data indicated that nerve fibres extend into and mast cells infiltrate the surrounding area of the skin lesion. NGF production by XB-2 cells, which was derived from mouse keratinocytes, was enhanced by histamine via the H1 receptor. We also found that prolonged treatment with an H1-antagonist was effective against pruritus through depression of the production of NGF, which is thought to be generated by keratinocytes. We conclude that DS-Nh mice can serve as a suitable model for gaining a better understanding of pruritus in AD, and that prolonged treatment with an H1-antagonist may be beneficial in patients with AD-associated pruritus.

Antihistamines in Dermatology

Along with antibiotics, antihistamines are the most widely used systemic drugs in dermatology. This is attributable to the major role played by histamine in common diseases such as urticaria and atopic eczema. Of the currently recognised four subtypes of G protein-coupled histamine receptors, only the H1 and H2 subtypes have been positively identified in human skin. Traditionally believed to be competitive antagonists of histamine, H1 and H2 antihistamines are now considered to behave as inverse agonists. By consensus, H1 antihistamines are classified as 'first generation' (associated with troublesome side-effects including somnolence, anti-adrenergic and atropine-like actions) and 'second-generation' compounds (in which these side-effects are reduced or absent). The main indications for H1 antihistamines in skin are suppression of pruritus in urticaria and atopic eczema, both of which are associated with increased mast cell numbers and tissue histamine levels. However the evidence basis for use in atopic eczema is ambiguous and controversial, even though these drugs are widely used in practice. Currently, significant side-effects are mainly confined to the first-generation compounds and are especially troublesome in the elderly. Psychomotor impairment may persist throughout the day following administration. Anti-cholinergic and anti-alpha-adrenergic blockade and cardiotoxicity (torsade de pointes) may also occur with first-generation antihistamines. Two early low-sedation second-generation antihistamines caused arrhythmias in a small number of patients but these compounds have now been withdrawn. Generally, the second-generation H1 antihistamines are well tolerated.

Effect of loratadine on mouse models of atopic dermatitis associated pruritus

To confirm the effectiveness of loratadine for relieving pruritus in atopic dermatitis, we examined the effect of this drug using animal models of atopic dermatitis associated pruritus in ICR and hairless mice. As for the results, in ICR mice, single oral administration of loratadine at a dose of 5 or 10 mg/kg significantly inhibited the dorsal scratching behavior induced by histamine or an antigen, and the effect of loratadine was more potent than that of fexofenadine and chlorpheniramine. In hairless mice, oral administration of loratadine at a dose of 10 mg/kg for 6 days significantly inhibited the facial scratching behavior induced by the feeding of a low magnesium diet. Furthermore, oral administration of loratadine at a dose of 10 mg/kg for 7 days also significantly inhibited the histamine-induced scratching behavior in the same animals. These results indicate that loratadine may be effective in preventing pruritus associated with atopic dermatitis.

A clinician's paradigm in the treatment of atopic dermatitis

Successful management of atopic dermatitis requires a multipronged approach that includes skin barrier function care, use of topical or systemic agents, and identification and elimination of precipitating or exacerbating factors. Because the origin of atopic dermatitis is multifactorial and trigger factors differ among patients, treatment plans must be specific to the individual patient. This article offers an example of a permutational, or flexible, treatment paradigm. The approach utilizes 4 topical regimens--high-potency topical corticosteroids, lowest effective potency topical corticosteroids, topical calcineurin inhibitors (TCIs), or topical corticosteroid/TCI combinations--as initial therapy in a variety of induction protocols, as determined by the severity of a patient's condition and history. The paradigm permits treatment to progress from a chosen induction therapy to maintenance therapy. During the patient's induction therapy, as soon as an acceptable level of clearance is achieved, therapy should be adjusted to a maintenance regimen, such as monotherapy with either a TCI or a lowest effective potency topical corticosteroid (the latter used intermittently) or an alternation of the two agents. If there is no clearance or positive response with the initial induction protocol, the clinician should move to one of the alternative regimens.

An Alternative Approach to Atopic Dermatitis: Part II-Summary of Cases and Discussion

In the first part of this Review, we presented case-series where Kampo treatment was introduced for those atopic dermatitis (AD) patients who had failed with conventional therapy, in an attempt to prove that there exists a definite subgroup of AD patients for whom Kampo treatment is effective. In this second part, we will first provide the summary of the results for 140 AD patients we treated in 2000. The results suggest that Kampo treatment is effective for more than half of AD patients who fail with conventional therapy. In the Discussion, we will examine the evidential basis for conventional AD therapy and discuss how Kampo treatment should be integrated into the guidelines for AD therapy. We contend that Kampo treatment should be tried before systematic immunosuppressive agents are considered. As each Kampo treatment is highly individualized, it should be regarded more as 'art' than technology, and special care should be taken to assess its efficacy in clinical trial.

Recent Advances in Treatment Strategies for Atopic Dermatitis

A wide range of different therapeutic regimens are used for atopic dermatitis. Although many treatment modalities are well established worldwide among clinicians, only the minority of these therapy recommendations are based on results of randomised controlled trials (RCTs). To close the gap between such 'generally' recommended therapies and therapies that are based on data from controlled trials, this review focuses not only on the pharmacological and clinical aspects of the currently proven agents, but also on the advantages and disadvantages of therapies that have not yet been completely tested.A review of the available literature concerning the pharmacological profile and also the level of evidence of therapeutic efficacy of all currently known topical and systemic agents for the treatment of atopic dermatitis reveals a large gap between the knowledge concerning the pharmacological action in vitro and the evidence of clinical efficacy in many cases. We agree with the conclusion of previous reviews that numerous therapies for atopic dermatitis urgently require more independent RCTs and especially comparative trials (e.g. corticosteroids vs calcineurin inhibitors). These are required in order to facilitate the choice of therapeutic strategy for the individual treatment of atopic dermatitis, with its broad spectrum of clinical manifestations and potential complications in adult patients and, particularly, in children.Finally, we also review preclinical trials with several new drugs. Immunomodulators appear to promise a new dimension for the future of therapy for atopic dermatitis, especially for severe and otherwise refractory forms or as alternatives to corticosteroids, that is, to treat facial atopic eczema without the risk of adverse effects.

Antihistamines

In the 1990s, major improvements occurred in the therapeutic index of H1 antihistamines. The third-generation compounds promise to be more effective and nontoxic. The future major advances are likely to result from development and exploitation of non-H1 receptor-mediated antiallergic actions of these drugs.

Objective scratch monitor evaluation of the effect of an antihistamine on nocturnal scratching in atopic dermatitis

We previously reported a simple and easy-to-use device, Scratch Monitor for evaluation of nocturnal scratching. In the present study, the effect of an antihistamine (azelastine hydrochloride) on atopic dermatitis was investigated using this device. In 40 patients with atopic dermatitis, nocturnal scratching was measured by the monitor, when taking the drug and while off medication. Neither the 'sleeping time' nor the 'pre-asleep time' differed significantly, but there was a significant difference in 'scratch rate', 'minute scratch records', 'hourly awake number' and 'awake rate', which indicated that this drug alleviated nocturnal scratching and sleep disturbance. The difference was most prominent especially in patients with a serum IgE > or = 1000 IU/ml as well as in patients with mild symptoms and normal serum lactate dehydrogenase levels. The drug was more effective for nocturnal scratching in the early period, when the 'sleeping time' was divided into three equal parts (early, mid and late periods) and each period was compared.

Itch and atopic dermatitis: an overview

Itching is the hallmark of atopic dermatitis, and a vicious itch-scratch circle is easily established. Itching and scratching are important factors in the maintenance of symptoms and can have a significant impact on the sufferer's quality of life. The pathophysiology of itch in atopic dermatitis is still not understood. Unlike in urticaria, histamine is not considered to be a major pruritogen in atopic dermatitis. In fact, the peripheral pruritogens and their cellular origin(s) still remain to be identified in this disease. Various treatments are used to relieve the skin inflammation, itching, and scratching in patients with atopic dermatitis, but no specific antipruritic therapy is available. However, several nonspecific therapies can effectively break the vicious itch-scratch circle. The use of topical corticosteroids and emollients and the elimination of individual trigger factors are still first-line measures.

Allergic dermatoses

Defining "allergy" and elucidating the immunopathology of what is too often described as allergic rashes is the objective of this article. The differentiation of inflammatory reactions, which at times is indistinguishable from the immunologic dermatoses is outlined. A rationale plan for management, with indications warranting referral to "the specialist" are suggested.

Effects of histamine H1 receptor antagonists on compound 48/80-induced scratching behavior in mice

The effects of histamine H1 receptor antagonists on compound 48/80-induced scratching behavior were studied in mice. Classical histamine H1 receptor antagonists such as diphenhydramine and chlorpheniramine caused a potent depressant effect on compound 48/80-induced scratching behavior. Histamine H1 receptor antagonists having antiallergic activity (an inhibition of mast cell degranulation), such as azelastine and oxatomide and nonsedative histamine H receptor antagonists such as terfenadine, epinastine and astemizole, also showed a relatively potent effect. On the other hand, the effects of tranilast and cromolyn sodium--antiallergic drugs without histamine H1 receptor antagonistic activity--were extremely weak. Diazepam had weak or no depressant effects on compound 48/80-induced scratching behavior. These results suggest that inhibition of compound 48/80-induced scratching behavior is mainly due to histamine H1 receptor antagonistic activity and not to the sedative action of the drugs.

Failure of terfenadine as an antipruritic agent in atopic dogs: results of a double-blinded, placebo-controlled study

Terfenadine (5 mg/kg body weight, q12h) and placebo (0.5 grain/dog q12h) were both administered orally as individual agents to 18 dogs with atopy in a double-blinded study. No dog improved. Hyperactivity, polyphagia, lethargy, anorexia, increased pruritus, or ocular discharge were seen in three dogs treated with terfenadine. Under the conditions of the study, terfenadine was not a useful antipruritic agent for the atopic dog.

Therapeutic effect of loratadine on pruritus in patients with atopic dermatitis. A multi-crossover-designed study

The aim of the study was to assess the therapeutic efficacy of loratadine on pruritus in patients with atopic dermatitis, considering the patients' sensation of itch. Sixteen patients, mean age 24.8 years, with moderate or severe atopic dermatitis were included in a double-blind and placebo-controlled study with a six-period, multi-crossover design. The patients were given 10 mg loratadine or placebo every day, alternating between loratadine and placebo every 2 weeks. The degree of pruritus during the day and during the night was recorded by the patients every morning and every evening, respectively, on a 10-cm visual analog scale. The study detected a significant effect of loratadine, as compared with placebo, on pruritus during the day, pruritus during the night, and severity of rash. At least nine of the 16 patients included were classified as responders and only one as a nonresponder to loratadine treatment. It is concluded that loratadine may be tried as an adjuvant therapy in the management of severe and moderate atopic dermatitis, in patients complaining of pruritus.

Pruritus: a practical approach

Pruritus is usually caused by a primary disorder of the skin, but can also be caused by a systemic disease (Table 1). Some dermatologic conditions that cause pruritus can be inconspicuous or nonspecific (Table 2), while others are usually apparent on physical examination (Table 3). Classification of pruritus as localized (Fig. 1) vs. generalized (Fig. 3) can be helpful in arriving at a correct diagnosis. The history and physical examination are the most important diagnostic tools, though laboratory testing for systemic disease may be necessary. In refractory cases, one should consider occult systemic disease (such as malignancy), psychiatric disease (especially depression), and HIV infection. Subsequent referral to a dermatologist may be indicted. When treatment of the underlying cause of pruritus is not possible, antihistamines and topical agents (menthol, phenol, and/or pramoxine) can be helpful.

Pharmacokinetic optimisation of histamine H1-receptor antagonist therapy

Second-generation, relatively nonsedating histamine H1-receptor antagonists (H1-RA) are extensively used worldwide for the symptomatic treatment of allergic rhinoconjunctivitis and chronic urticaria. Information about the pharmacokinetics and pharmacodynamics of these medications, while still incomplete, is now sufficient to permit optimisation of therapy. Published pharmacokinetic and pharmacodynamic information on these H1-RA is summarised here, and areas where more data are required are delineated. Serum concentrations of most second-generation H1-RA are relatively low, and are usually measured by radioimmunoassay. After oral administration, peak concentrations are observed within 2 or 3 h. Bioavailability has not been well studied, due to the lack of intravenous formulations. Most H1-RA are metabolised in the hepatic cytochrome P450 system: terfenadine, astemizole, loratadine, azelastine, and ebastine have 1 or more active metabolites which are present in serum in higher concentrations than the respective parent compound, and therefore can be measured by high performance liquid chromatography. Cetirizine, an active metabolite of the first generation H1-receptor antagonist hydroxyzine, is not further metabolised to any great extent in vivo, and is eliminated via renal excretion. Levocabastine is also eliminated primarily by excretion. Serum elimination half-life values differ greatly from 1 H1-RA to another, and are 24 h or less for terfenadine, astemizole, loratadine, cetirizine, azelastine and ebastine, and the active metabolites of terfenadine, loratadine and ebastine. The active metabolite of azelastine (demethylazelastine) has a serum elimination half-life value of about 2 days, while that of astemizole (demethyl-astemizole) has a value of 9.5 days. From the few published studies in which the apparent volumes of distribution of the second-generation H1-RA have been calculated, it appears that tissue distribution is extensive. In children, the half-lives of H1-RA are generally shorter than are found in adults; there is no published information on the pharmacokinetics of astemizole, loratadine, azelastine, or ebastine in children. In some elderly adults, terfenadine, loratadine and cetirizine may have longer half-lives than in young healthy adults. There is little published data on the pharmacokinetics of the second-generation H1-RA in patients with impaired hepatic function. The half-life of cetirizine is prolonged in those with impaired renal function. There is a paucity of information on the pharmacokinetics of H1-RA in neonates, in pregnancy or during lactation.(ABSTRACT TRUNCATED AT 400 WORDS)

Atopic dermatitis: new therapeutic considerations

Atopic dermatitis is a genetically determined inflammatory condition in which the primary defect is expressed in one or more hematopoietic cells that infiltrate the skin. It is a multifactorial disease with inflammation triggered by a variety of factors. Among these, atopic dermatitis has been experimentally induced and reproduced by emotional-stress interviews and food challenges only. The inflammatory events of atopic dermatitis appear to initiated by mast cells, but eosinophils, monocytes, and T lymphocytes (predominantly CD4) also are present in lesions. The secondary effects of inflammation are a dry, brittle stratum corneum and pruritus, causing excoriation and a lichenified epidermal layer resulting from chronic rubbing. Therapeutic approaches to atopic dermatitis may be directed at several points in the evolution of the disease. Agents including emollients are needed to preserve and restore the stratum corneum barrier, and effective antipruritics are required to reduce the self-inflicted damage to the involved skin. Various other agents may be needed to antagonize mediators or cytokines and to inhibit cytokine expression and release from lesional, immune-effector cells. Likewise, new phosphodiesterase inhibitors, calcium-active agents, and antiallergic drugs may be used to reduce the quantity and pathologic functioning of inflammatory infiltrating cells in the skin.

Acrivastine. A review of its pharmacological properties and therapeutic efficacy in allergic rhinitis, urticaria and related disorders

Acrivastine is a short acting histamine H1-receptor antagonist with a rapid onset of action. Double-blind clinical trials have shown acrivastine (usually 8mg three times daily) to be an effective and well tolerated antihistamine in the treatment of chronic urticaria and allergic rhinitis. Acrivastine was more effective than placebo and similar in efficacy to clemastine or terfenadine in the treatment of seasonal allergic rhinitis. In the treatment of dermatoses in which histamine has a pathogenetic role, the efficacy of acrivastine was superior to that of placebo and similar to that of usual dosages of clemastine, hydroxyzine, chlorpheniramine, cyproheptadine or terfenadine. Acrivastine caused less drowsiness than clemastine, the incidence of adverse effects being indistinguishable from that with placebo or terfenadine. Thus, acrivastine is an effective addition to drugs currently available for the treatment of patients with allergic diseases in whom a histamine H1-receptor antagonist is indicated. Because of its rapid onset of action acrivastine will be particularly useful for 'on demand' therapy in patients with intermittent symptoms.