Retrospective review of the use of azathioprine in severe atopic dermatitis

MMF and Eye Disease

Immunosuppressive treatment has shown to be effective in various ocular inflammatory disorders. Factors limiting their use are the individual response and the rate of side effects. This report summarizes our knowledge about the use of mycophenolate mofetil (MMF) in the treatment of ocular cicatricial pemphigoid (OCP), uveitis, atopic keratoconjunctivitis (AKC), prevention of graft rejection after penetrating keratoplasty (PK) and scleritis. Controlled studies have been performed for prevention of graft rejection after PK, showing MMF as effective in the prevention of graft rejection as cyclosporine A. In experimental uveitis, MMF has been demonstrated to be highly effective in prevention of retinal destruction. A number of studies have now shown that MMF also seems effective in uveitis. There are also studies with smaller patient groups which point out the effectiveness of MMF in OCP, AKC, and scleritis. In most of the studies, the spectrum of side effects was small, compared to other immunosuppressives.

Eczema

Atopic dermatitis, commonly known as eczema, is a common chronic, relapsing skin disease characterized by pruritus, disrupted epidermal barrier function, and immunoglobulin E-mediated sensitization to food and environmental allergens. Atopic dermatitis is a complex disease that arises from interactions between genes and the environment. Loci on several chromosomes have been identified, including a family of epithelium-related genes called the epidermal differentiation complex on chromosome 1q21. Mutations in filaggrin, a key protein in epidermal differentiation, have also been identified in early-onset and severe atopic dermatitis. There are 3 classical stages of eczema: infantile, childhood, and adulthood. The spectrum of eczema presentation varies widely from a variant that only affect the hand to major forms where a patient presents with erythroderma. The acute and subacute lesions of atopic dermatitis are often characterized by intensely pruritic, erythematous papules and vesicles with excoriations and a serous exudate. Chronic atopic dermatitis is exemplified by lichenified plaques and papules with excoriations. Atopic dermatitis patients are also at higher risk for skin infections, including bacterial and viral superinfections. Conventional therapy includes avoidance of irritants and potential allergens, as well as continued hydration of the skin with thick emollients. Topical corticosteroids and topical immunomodulators are often used primarily. Other therapies including phototherapy, antimicrobials, antihistamines, and systemic immunosuppressives are also options in certain situations.

Atopic dermatitis: systemic immunosuppressive therapy

Atopic dermatitis (AD) is a pruritic, relapsing skin disorder that negatively impacts the quality of life of those affected and that of their families. Treatment options for AD encompass a variety of emollients, topical corticosteroids, topical immunomodulators, phototherapy, and systemic agents. Such agents as systemic corticosteroids, cyclosporine, azathioprine, interferon-gamma, methotrexate, and mycophenolate mofetil have been shown to be efficacious in the treatment of moderate-to-severe AD but are not officially approved for this purpose. In this article, we review some of the data supporting efficacy of these medications and discuss some of the adverse events associated with their use.

Azathioprine in dermatology: The past, the present, and the future

For several decades, dermatologists have utilized azathioprine to treat numerous debilitating skin diseases. This synthetic purine analog is derived from 6-mercaptopurine. It is thought to act by disrupting nucleic acid synthesis and has recently been found to interfere with T-cell activation. The most recognized uses of azathioprine in dermatology are for immunobullous diseases, generalized eczematous disorders, and photodermatoses. In this comprehensive review, the authors present recent advancements in the understanding of azathioprine and address aspects not covered in prior reviews. They (1) summarize the history of azathioprine; (2) discuss metabolism, integrating information from recent publications; (3) review the mechanism of action with attention paid to the activities of azathioprine not mediated by its 6-mercaptopurine metabolites and review new data about inhibition by azathioprine of the CD28 signal transduction pathway; (4) thoroughly examine thiopurine s-methyltransferase genetics, its clinical relevance, and interethnic variations; (5) review prior uses of azathioprine in the field of dermatology and grade the level of evidence; (6) discuss the use of azathioprine in pregnancy and pediatrics; review (7) key drug interactions and (8) adverse effects; (9) suggest a dosing and monitoring approach different from prior recommendations; and (10) explore the future of azathioprine, focusing on laboratory considerations and therapeutic application.

Diagnosis and treatment of atopic dermatitis in children and adults: European Academy of Allergology and Clinical Immunology/American Academy of Allergy, Asthma and Immunology/PRACTALL Consensus Report

There are remarkable differences in the diagnostic and therapeutic management of atopic dermatitis practiced by dermatologists and pediatricians in different countries. Therefore, the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology nominated expert teams who were given the task of finding a consensus to serve as a guideline for clinical practice in Europe as well as in North America. The consensus report is part of the PRACTALL initiative, which is endorsed by both academies.

MMF and eye disease

Immunosuppressive treatment has shown to be effective in various ocular inflammatory disorders. Factors limiting their use are the individual response and the rate of side effects. This report summarizes our knowledge about the use of mycophenolate mofetil (MMF) in the treatment of ocular cicatricial pemphigoid (OCP), uveitis, atopic keratoconjunctivitis (AKC), prevention of graft rejection after penetrating keratoplasty (PK) and scleritis. Controlled studies have been performed for prevention of graft rejection after PK, showing MMF as effective in the prevention of graft rejection as cyclosporine A. In experimental uveitis, MMF has been demonstrated to be highly effective in prevention of retinal destruction. A number of studies have now shown that MMF also seems effective in uveitis. There are also studies with smaller patient groups which point out the effectiveness of MMF in OCP, AKC, and scleritis. In most of the studies, the spectrum of side effects was small, compared to other immunosuppressives.

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.

The Use of Systemic Immune Moderators in Dermatology: An Update

In addition to corticosteroids, dermatologists have access to an array of immunomodulatory therapies. Azathioprine, cyclophosphamide, methotrexate, cyclosporine, and mycophenolate mofetil are the systemic immunosuppressive agents most commonly used by dermatologists. In addition, new developments in biotechnology have spurred the development of immunobiologic agents that are able to target the immunologic process of many inflammatory disorders at specific points along the inflammatory cascade. Alefacept, efalizumab, etanercept, and infliximab are the immunobiologic agents that are currently the most well known and most commonly used by dermatologists. This article reviews the pharmacology, mechanism of action, side effects, and clinical applications of these therapies.

Guidelines for prescribing azathioprine in dermatology

Azathioprine has been available as an immunosuppressive agent for over 40 years, and current routine usage in dermatology is not restricted to licensed indications. Advances in understanding the metabolic fate of azathioprine have led to significant changes in prescribing practice and toxicity monitoring by U.K. dermatologists. The current state of knowledge concerning the use of azathioprine in dermatology is summarized, with identification of strength of evidence. Clinical indications and contraindications for azathioprine usage in dermatology are identified. Evidence-based recommendations are made for routine safety monitoring of patients treated with azathioprine, including pretreatment assessment of red blood cell thiopurine methyltransferase activity.

Azathioprine as a treatment for severe atopic eczema in children with a partial thiopurine methyl transferase (TPMT) deficiency

Azathioprine is a valuable agent in the treatment of severe childhood atopic eczema. Thiopurine methyl transferase (TPMT) exhibits autosomal codominant polymorphism and plays an important role in the metabolism of azathioprine. In most large population groups studied to date, approximately 10% of the population had intermediate activity due to heterozygosity at the TPMT locus, and about 0.33% were TPMT deficient. TPMT deficiency results in the accumulation of thioguanine nucleotides and cytotoxic 6-mercaptopurine metabolites. Previously it was considered unsafe to treat this group with azathioprine because of what was considered to be an unacceptably high risk of toxicity (profound myelosuppression). Better understanding of the pharmacogenetics of purine metabolism has changed this, and with appropriate dose adjustments, individuals who have a partial TPMT deficiency (heterozygotes) can now be treated with thiopurines. It seems probable that these individuals are more likely to have a therapeutic response while being at lower risk of developing dose-related hepatotoxicity because of the reduced doses required to effect a therapeutic response. Two patients with severe refractory atopic eczema, both of whom had a partial TPMT deficiency, have had an excellent response to treatment with azathioprine. They were treated with half-standard doses and response to treatment occurred within 2 weeks.

Itch

Itch is a common skin sensation, with substantial effects on behaviour. Neurophysiological research has permitted accurate definition of neural pathways of itch, and has confirmed the distinctiveness of itch pathways in comparison with pain. A clinical classification of itch, based on such improved understanding, describes the difference between peripheral (pruritoceptive) and central (neurogenic or neuropathic) itch. New specific and sensitive investigational methods in people and animals enable us to better understand this bothersome symptom, and have important clinical implications. We describe the clinical classification of itch, new findings on neuropathophysiology of itch, methods for assessment, and improved treatments.

A retrospective evaluation of azathioprine in severe childhood atopic eczema, using thiopurine methyltransferase levels to exclude patients at high risk of myelosuppression

BACKGROUND

Atopic eczema is a chronic inflammatory skin disease, which in most children can be adequately controlled using topical therapy. However, in a small number of children it is necessary to use systemic treatments to gain an acceptable level of disease control.

OBJECTIVES

To evaluate azathioprine as a treatment for severe atopic eczema in children, and the value of pretreatment thiopurine methyltransferase (TPMT) levels in the identification of patients at high risk of myelosuppression.

METHODS

Between January 1997 and May 2000, 91 children had erythrocyte TPMT assays with the intention of treating their atopic eczema with azathioprine. This study is based on retrospective examination of data taken from the hospital notes of these children, who had attended Great Ormond Street Hospital for Children and St John's Institute of Dermatology, London.

RESULTS

The distribution of TPMT values corresponded closely to that previously described in adults. Forty-eight children were commenced on treatment with azathioprine. Twenty-eight had an excellent response to treatment, 13 had a good response and seven had a poor response. No patient developed neutropenia.

CONCLUSIONS

Azathioprine may prove a very valuable treatment for severe atopic eczema in children. We consider its short-term adverse effect profile in children with normal TPMT activity to have been entirely acceptable with our treatment protocol. As result, we now feel confident to initiate therapy at dose levels of 2.5-3.5 mg kg(-1) in those with a normal TPMT level, and to reduce the frequency with which we undertake tests of bone marrow and liver function.

Azathioprine in severe adult atopic dermatitis: a double-blind, placebo-controlled, crossover trial

BACKGROUND

There is a limited range of treatments for severe atopic dermatitis (AD). Azathioprine has often been used but there has been no randomized controlled trial of this drug to confirm its efficacy in AD.

OBJECTIVES

To establish or refute the efficacy of azathioprine in severe AD. To investigate the safety and tolerability of azathioprine in this patient population.

METHODS

We performed a double-blind, randomized, placebo-controlled, crossover trial of azathioprine in adult patients with severe AD. Each treatment period was of 3 months' duration. Treatments were azathioprine 2.5 mg kg(-1) day(-1) and matched placebo. Disease activity was monitored using the SASSAD sign score. In addition, severity of pruritus, sleep disturbance and disruption of work/daytime activity were monitored using visual analogue scales. Adverse events were recorded and haematological and biochemical monitoring was performed.

RESULTS

Thirty-seven subjects were enrolled, mean age 38 years (range 17-73). Sixteen were withdrawn, 12 during azathioprine treatment and four during placebo treatment. The SASSAD score fell by 26% during treatment with azathioprine vs. 3% on placebo (P < 0.01). Pruritus, sleep disturbance and disruption of work/daytime activity all improved significantly on active treatment but not on placebo. The difference in mean improvement between azathioprine and placebo was significant for disruption of work/daytime activity (P < 0.02) but not for pruritus or sleep disturbance. Gastrointestinal disturbances were reported by 14 patients during azathioprine treatment and four were withdrawn as a result of severe nausea and vomiting. Leukopenia was observed in two patients and deranged liver enzymes in eight during treatment with azathioprine.

CONCLUSIONS

Azathioprine is an effective and useful drug in severe AD although it is not always well-tolerated. Monitoring of the full blood count and liver enzymes is advisable during treatment.

Clinical improvement and significant reduction of total serum IgE in patients suffering from severe atopic dermatitis treated with oral azathioprine

Atopic dermatitis (AD) is a common inflammatory skin disease: the incidence is increasing in many countries and treatment can be difficult. The aim of this retrospective case series was to examine the effect of oral azathioprine on the clinical severity and serum IgE levels in 38 patients with severe atopic dermatitis. The AD was well-controlled in nearly 80% (30/38). The maintenance dose required was in the range 25-200 mg per day. Four patients withdrew because of adverse affects, including one case of pancytopenia, and a further four ceased azathioprine after 4 months because of a lack of clinical improvement. Total serum IgE levels were measured before commencing azathioprine and after two years of treatment in 26 patients. IgE levels decreased in almost all patients and this was statistically significant (P = 0.012).

Pharmacoeconomics of drug therapy for atopic dermatitis

Atopic dermatitis is an increasingly prevalent common childhood disease. While the majority of patients have mild disease, atopic dermatitis can cause considerable distress to patients and their caregivers, with significant social and financial cost to families. With a prevalence of 15 - 20% in Western countries, atopic dermatitis also has a considerable health and societal cost to the community. Many new treatments have been shown to be therapeutically effective, particularly in severe disease, including cyclosporin A (Neoral, Novartis AG), interferon, tacrolimus (Fujisawa Pharmaceutical Co. Ltd.) and iv. immunoglobulin. These are expensive when compared to standard treatments like emollients and topical corticosteroids and have significant adverse effects that limit their use. Additional costs related to monitoring are incurred and the long-term safety of these treatments is yet to be determined. However, an advantage over more traditional therapies is their ability to produce benefits even after treatment ceases. Treatments that produce long-term remissions have a greater likelihood of being cost-effective. With monetary constraints on healthcare and the importance governments place on reducing drug costs, economic evaluations are becoming an increasingly important factor for drug acceptance. Those evaluating cost-effectiveness should pay particular attention to the potential reduction in indirect and intangible costs. Unfortunately, there is a dearth of cost-effectiveness studies in atopic eczema and this needs to be addressed with some urgency.

Azathioprine for atopic dermatitis

For adults with atopic dermatitis (AD) refractory to topical treatment, the choices of second-line therapy are limited. Furthermore, there are concerns about the long-term safety of treatments such as cyclosporin. Limited open studies suggest that azathioprine may be effective, although controlled trial data is lacking. Nevertheless, many UK dermatologists use azathioprine to treat patients with severe AD, despite the potential risk of serious toxicity. Azathioprine myelotoxicity and drug efficacy are now known to be related to the activity of a key enzyme in azathioprine metabolism, thiopurinemethyltransferase (TPMT). Recently, the facility for TPMT measurement has become more widely available, providing the possibility to optimize the therapeutic effect of azathioprine, yet minimise the risk of toxicity. We review the evidence concerning the use of azathioprine for AD, and have identified 128 cases in eight open studies, including our own prospective trial. Improvement in the majority was noted in seven studies, although objective measures of disease activity were used in only one trial. Measurements of TPMT activity were performed in the two most recent studies only. These data underscore the requirement for a prospective randomised controlled trial, and highlight the need to further investigate the role of TPMT measurement in azathioprine usage.

Antimetabolites and cytotoxic drugs

Mycophenolic mofetil, azathioprine, thioguanine, methotrexate, and cyclophosphamide were initially used for the treatment of malignancies. Because of their immunosuppressive activity, the range of diseases responsive to these medications has expanded to include various autoimmune-related diseases. Discussion includes a historical perspective of each medication, recent updates on responsive dermatologic conditions, dosages, monitoring guidelines, and medication expense.

Old, new, and emerging therapies for atopic dermatitis

Atopic dermatitis is the most common skin condition in children under the age of 11 years. The chronic, cyclical, pruritic course of AD exacts a huge financial and emotional toll on its sufferers. Confusion about appropriate skin care and the role of allergic factors further complicates management. Although diligent moisturization and judicious use of topical steroids remain the therapeutic standard, new, effective local and systemic agents are now available, and several promising nonsteroidal products may be available soon.

Immunosuppressive agents in dermatology. An update

Azathioprine, cyclophosphamide, methotrexate, and cyclosporine are the immunosuppressive agents most commonly used by dermatologists. Azathioprine has a relatively good safety profile and is therefore often preferred for the treatment of chronic eczematous dermatitides and bullous disorders. Awareness of the role of genetic polymorphisms in its metabolism can increase the efficacy and safety of this drug. Cyclophosphamide is an antimetabolite that has a more rapid onset of immunosuppressive effect than azathioprine, but has significant short-term and long-term toxicity. It is of use in fulminant, life-threatening cutaneous disease. Methotrexate is an antimetabolite that has significant anti-inflammatory activity. Despite its hepatotoxicity, its role in inflammatory dermatoses is broadening. Likewise, the role of cyclosporine is being expanded. This drug has potent T-cell inhibitory effects secondary to interference with intracellular signal transduction. Given the evidence for cumulative renal toxicity, it currently has a role in the short-term treatment of refractory psoriasis and atopic dermatitis, as well as in select inflammatory dermatoses. Familiarity with disease-specific clinical efficacy, side-effect profile, and dosage allows the successful and judicious use of these drugs in dermatologic disorders.