Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0042109 (urticaria)
 6,569 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adverse hypersensitivity reactions to natural foods and certain drugs and food additives are mediated by immunological (allergy) or non-immunological mechanisms. Some clinical and physiological similarities have been noted between these allergic and non-allergic reactions. This observation has led to the concept of "pseudoallergic reactions-PAR". PAR can be triggered in various ways such as: interactions with the central or peripherical nervous system, non-specific release of mediators, enzyme inhibition due to hereditary or pharmacologically induced enzyme deficiencies and pharmacological properties of some natural food constituents such as biogenic amines. The prevalence of adverse reactions to food additives has been calculated to be about 0.1%. PAR to food additives occurs frequently in patients suffering from urticaria, asthma and may be accompanied by history of aspirin or NSAI pseudoallergic reactions. The same additives (azo dyes, sulphites, benzoates) are used in various drug formulations and may be responsible for eliciting PAR. In Poland, labelling of food additives, following the "E number system", has been mandatory since 1993. Unfortunately, this satisfactory trend has not yet been applied to drug additives. The diagnosis of PAR to food additives is based on the anamnesis with analysis of the patient's drug and dietary intake. Skin tests and "in vitro" tests are only sporadically informative. In each individual patient, a specific challenge with additives is desirable. Food additives may be tested according to the schedule based on DBPCFC principle. Individually performed exclusion regimes are the principal methods of prevention.
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PMID:[Pseudoallergic reactions. Intolerance to natural and synthetic food constituents masquerading as food allergy]. 892 81

Levocetirizine is the most recent antihistamine available in the United States and is indicated for the symptomatic treatment of allergic rhinitis (AR; seasonal [SAR] and perennial [PAR]) and chronic idiopathic urticaria (CIU). The purpose of this study was to review the current literature on pharmacologic properties of levocetirizine, its safety, tolerability, and effectiveness in AR and CIU. Relevant articles in English or with English abstracts were identified from systematic Medline searches using combinations of the terms antihistamine/s, CIU, H(1)-receptor antagonist/s, levocetirizine, PAR and persistent AR (PER), pharmacodynamic, pharmacokinetic, and SAR. Levocetirizine is the active enantiomer of cetirizine. Pharmacologic and clinical studies indicate that levocetirizine has a fast onset and long duration of action, with a well-tolerated adverse effect profile. These favorable features may be caused by levocetirizine's pharmacokinetic and pharmacodynamic properties including high bioavailability, low apparent volume of distribution, low degree of metabolism, and high in vivo potency and H(1)-receptor occupancy. Several large well-controlled clinical trials in adults and children aged 6-12 years have shown levocetirizine to be consistently efficacious and well tolerated in relieving the symptoms of SAR, PAR, and PER and CIU. Levocetirizine is a welcome new treatment option in the United States for symptomatic treatment of AR and CIU.
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PMID:Levocetirizine: The latest treatment option for allergic rhinitis and chronic idiopathic urticaria. 1820 39

Contrary to common believing, the prevalence of the intolerance to food additives in the general population is rather low. Nowadays many doubts persist with regard both to the pathogenetic mechanisms and to the clinical and diagnostic aspects in this field. Symptoms due to, or exacerbated from, food additives usually involve non-IgE-mediate mechanisms (pseudo-allergic reactions, PAR) and are usually less severe of those induced by food allergy. The most frequent clinical feature of the intolerance to food additives still remains the urticaria-angioedema syndrome, although these substances are really involved only in a minority of patients. Other possible clinical features include anaphylaxis, atopic eczema, behaviour disturbances, asthma and non-allergic rhinitis. The diagnostic approach consists in diary cards, reporting symptoms and food habits, elimination diet and double blinded placebo-controlled oral challenge with suspected additives. However, such procedure still remains poorly standardized and numerous uncertainties persist with regard to optimal conditions for performing and interpret the challenge results. The therapeutic approach consists in the exclusion of foods and products containing the additive involved, and, in patients not compliant to the diet, in treatment with symptomatic drugs.
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PMID:[Intolerance to food additives: an update]. 1897 1