Chronic urticaria: assessment of current treatment

Pharmacology of antihistamines

H1-antihistamines, the mainstay of treatment for urticaria, were developed from anticholinergic drugs more than 70 years ago. They act as inverse agonists rather than antagonists of histamine H1-receptors which are members of the G-protein family. The older first generation H1-antihistamines penetrate readily into the brain to cause sedation, drowsiness, fatigue and impaired concentration and memory causing detrimental effects on learning and examination performance in children and on impairment of the ability of adults to work and drive. Their use should be discouraged. The newer second-generation H1-antihistamines are safer, cause less sedation and are more efficacious. Three drugs widely used for symptomatic relief in urticaria, desloratadine, levocetirizine and fexofenadine are highlighted in this review. Of these levocetirizine and fexofenadine are the most potent in humans in vivo. However, levocetirizine may cause somnolence in susceptible individuals, whereas fexofenadine has a relatively short duration of action and may be required to be given twice daily for all round daily protection. Although desloratadine is less potent, it has the advantages of rarely causing somnolence and having a long duration of action.

H(1)-antihistamines and urticaria: how can we predict the best drug for our patient?

Urticaria, and especially chronic spontaneous urticaria (CSU), is a difficult condition to treat. Consequently, clinicians need to use the best H(1)-antihistamines currently available and the pharmaceutical industries need to keep developing H(1)-antihistamines that are more effective than the ones we have today. To do this we need to be able to compare the clinical efficacy of both established and new drugs. Obviously, the ideal way to do this is to use head-to-head studies in CSU. However, such studies are extremely expensive and, in the case of novel molecules, have ethical and logistical problems. Consequently, we need to have predictive models. Although determination of Ki, an indicator of the in vitro potency of an H(1)-antihistamine, may help in the initial selection of candidate molecules, the large differences in volume of distribution and tissue accumulation in humans, precludes this from being a good predictor of clinical efficacy in CSU. From the data reviewed in this article, especially the direct comparative data of desloratadine and levocetirizine in weal and flare studies and CSU, weal and flare response would appear to be the best indicator we have of effectiveness of H(1)-antihistamines in clinical practice. However, it must be pointed out that the conclusion is, essentially, based on detailed comparisons of two drugs in studies sponsored by pharmaceutical companies. Consequently, to confirm the conclusions of this review, a multicentre study independent from the influence of pharmaceutical companies should be commissioned to compare the speed of onset and effectiveness of desloratadine, fexofenadine and levocetirizine in chronic spontaneous urticaria and against histamine-induced weal and flare responses in the same patients so that we have a clear understanding of the predictive value of our models.

Diagnosis and treatment of urticaria and angioedema: a worldwide perspective

: Urticaria and angioedema are common clinical conditions representing a major concern for physicians and patients alike. The World Allergy Organization (WAO), recognizing the importance of these diseases, has contributed to previous guidelines for the diagnosis and management of urticaria. The Scientific and Clinical Issues Council of WAO proposed the development of this global Position Paper to further enhance the clinical management of these disorders through the participation of renowned experts from all WAO regions of the world. Sections on definition and classification, prevalence, etiology and pathogenesis, diagnosis, treatment, and prognosis are based on the best scientific evidence presently available. Additional sections devoted to urticaria and angioedema in children and pregnant women, quality of life and patient-reported outcomes, and physical urticarias have been incorporated into this document. It is expected that this article will supplement recent international guidelines with the contribution of an expert panel designated by the WAO, increasing awareness of the importance of urticaria and angioedema in medical practice and will become a useful source of information for optimum patient management worldwide.

An approach to the patient with urticaria

Patients with urticaria make up a large proportion of the referrals to allergy clinics. There are many causes of urticaria and it is the clinical history which is most important when attempting to identify potential causes; however, urticaria is very often idiopathic. In a small minority of patients urticaria may be a symptom of a serious underlying medical illness or the allergic symptoms may progress to cause systemic reactions, and it is important to identify these patients and to remember that severe urticaria is a distressing and disabling condition. This review will discuss classification, investigation and treatment of urticaria and will consider some of the more unusual types of urticaria that may be encountered in the out-patient clinic.

Urticaria

Urticaria and angioedema are common and, if chronic, often persist for years with significant impact on quality of life and occupational ability. To achieve a better understanding of disease etiology and pathogenesis and to compare clinical trials, there is a clear need for cross-specialty and international agreement of the nomenclature and diagnostic classification of urticaria and angioedema. At least in part this has been achieved by two recently published European guidelines. After the urticaria subtype is defined, potential triggers should be sought including persistent bacterial infections (Helicobacter pylori, streptococci, staphylococci, Yersinia, parasites) pseudoallergic reactions (acetylsalicylic acid, rarely food additives) and/or autoreactive mechanisms (autologous serum test). Identified trigger factors should be avoided or eradicated, as this is the most successful therapeutic approach. Treatment of most urticaria subtypes is difficult and besides H1 antihistamines neither standardized nor evidence-based. Low-sedating H1 antihistamines represent the mainstay of treatment, as they have a better therapeutic index and pharmacodynamic properties than older agents. In severe cases their dose has to be increased which is off-label use. The evidence base for treatment alternatives is totally insufficient and the risk-benefit profile of each off-label used drug should be carefully considered.

Moderne Diagnostik und Therapie der Urtikaria

The different urticaria subtypes represent a common diagnostic and treatment challenge for the dermatologist. Usually, acute urticaria is treated symptomatically with modern H1 antihistamines and, if needed, short courses of glucocorticosteroids. In acute urticaria which is often induced by an acute infection no further diagnostic procedures are recommended. In contrast, a targeted work-up followed by specific therapy is required for chronic urticaria, physical urticaria and special urticaria types, because many of these subtypes are characterized by their persistence for several years and have a profound impact on the quality of life. This article elucidates the management of urticaria by presenting five characteristic case reports of patients managed in a special urticaria consulting hour.

Chronic unremitting urticaria: is the use of antihistamines above the licensed dose effective? A preliminary study of cetirizine at licensed and above-licensed doses

Recently, several authors have suggested an off-label increase of antihistamine dosage should be given to patients with chronic urticaria (CU) not responding to the usual, recommended doses, in order to gain better control of the disease. However, this recommendation is not evidence-based. The objective of this study was to assess the effectiveness of increased doses of antihistamines in patients with CU showing poor control at recommended doses. In total, 22 adult patients with moderate/severe CU not controlled with the usual antihistamine doses were studied. These subjects recorded urticaria severity on a visual analogue scale (range 0-10) for 2 weeks. During the first week, they were treated with cetirizine at the licensed dose (10 mg/day), and with a three-fold increased dose (10 mg x 3/day) during week 2. Only 1 patient (5%) responded satisfactorily to the increased dosage of antihistamine; in the remaining 21 subjects, urticaria scores did not change, and these patients had to be treated with steroids, ciclosporin, and in 1 case with cyclophosphamide. Disease control was eventually gained in all cases. This study suggests that the proportion of patients with severe CU that may gain a better control of their disease with high, off-label doses of antihistamines is probably small, and that most patients will eventually have to undergo more aggressive treatments.

Emerging drugs for chronic urticaria

Chronic urticaria (CU), with or without angioedema, is a frequent disorder defined as the occurrence of pruritic wheals for > 6 weeks. Studies carried out in the last two decades showed that the origin of the disease is autoimmune in up to 50% of cases. Currently available treatments include antihistamines, corticosteroids and ciclosporin; recently, leukotriene receptor antagonists proved effective in a subset of patients as well. For patients with an unremitting and extremely severe disease unresponsive to standard treatments, plasmapheresis and immunosuppressive drugs have been successfully attempted. Recent findings that the autologous plasma skin test scores positive in nearly all patients and that plasmas from patients with both autoimmune and 'idiopathic' chronic urticaria are frequently characterised by signs of thrombin activation (plasma levels of prothrombin fragment F(1.2) are significantly increased) suggest that clotting cascade might be somehow involved in the pathogenesis of CU. These findings put under a new light some rather sparse studies of the effect of drugs active on the coagulation system (heparin and oral anticoagulants) in patients with CU.

Aktuelle Positionsbestimmung zur Bedeutung von Nahrungsmittelallergien und -unverträglichkeiten bei der Urtikaria

Foods are usually the first suspect as the cause of urticaria. However, a causal relationship is found only in special subtypes of urticaria. IgE-mediated food allergy should be clearly separated from non-allergic hypersensitivity (pseudoallergic reactions). The former may play a role in acute urticaria, particularly in patients with atopic dermatitis. The responsible food proteins vary with age. IgE-mediated sensitization can apply to food-dependent exercise-induced urticaria/anaphylaxis but more often the combination of food intake (irrespective of which type) plus exercise results in symptoms. In chronic urticaria, IgE-mediated sensitization to food is normally irrelevant while pseudoallergic reactions to food additives and perhaps also to biogenic amines may be involved. Another urticaria subtype that may be caused by food is contact urticaria which is mostly found in the context of occupational food handling. Very rarely anisakiasis and nickel may cause food-induced urticaria. Aspirin is able not only to exacerbate and aggravate urticaria but can also enhance food-dependent urticaria.