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)

H(1)-antihistamines are widely used in the treatment of various allergic diseases. Particularly, a cornerstone of the management of chronic idiopathic urticaria is treatment with H(1)-antihistamines. However, a few cases of H(1)-antihistamine-induced urticaria have been reported. A 34-year-old woman presented with a 4-month history of recurrent urticaria, which was prominently exacerbated by the administration of H(1)-antihistamines. The patient consented to a provocation test of fexofenadine among drugs including cetirizine and hydroxyzine, which were suspected of inducing severe symptoms in episodes. One hour after challenge with 12 mg fexofenadine (one-fifth of the therapeutic dose), a urticarial reaction rapidly developed on nearly the entire body with remarkably increased levels of plasma histamine (190 nmol/L) and plasma leukotriene B4 (150 pg/mL). In challenge tests with other antihistamines, generalized urticaria occurred 5 and 1 h after intake of 10 mg loratadine and 10 mg bepotastine, respectively, whereas challenges with chlorpheniramine, mequitazine and azelastine were all negative. Skin prick tests with H(1)-antihistamines used in the challenges were all negative, indicating that the urticarial reactions after challenges with the causative drugs might not be immunoglobulin E-mediated. Among the causative drugs in our case, cetirizine and hydroxyzine are the piperazine derivatives, whereas fexofenadine, bepotastine, ebastine and loratadine are the piperidine derivatives. The chemical structures of both derivatives are very similar. Therefore, in this case, H(1)-antihistamine-induced urticaria may have been due to cross-reactivity between metabolites of these drugs, but not to drugs before metabolization. Hypersensitivity to H(1)-antihistamines should be considered when urticarial lesions worsen after H(1)-antihistamine treatment.
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PMID:Multiple H1-antihistamine-induced urticaria. 1934 61

Histamine is the main mediator of urticaria and H1-receptor antagonists represent the treatment of choice in all patients with chronic urticaria. Leukotriene receptor antagonists as montelukast have also been used in patients with chronic urticaria unresponsive to H1-antihistamines alone. We report a patient with chronic urticaria whose disease was paradoxically exacerbated by H1-antihistamines and montelukast, and controlled by immunosuppressive drugs as ciclosporin and azathioprine. Urticaria exacerbations were caused by different molecules including either piperidine (fexofenadine, desloratadine, ebastine, rupatadine) or piperazine (hydroxyzine, cetirizine) derivatives as well as by montelukast suggesting that an IgE-mediated mechanism was not involved. A possible explanation of the observed urticaria exacerbation is that H1-antihistamines and montelukast may shift the H1 histamine receptor and the leukotriene receptor to the active conformation instead of the inactive state. The beneficial effects of ciclosporin and azathioprine confirm that immunosuppressive drugs have an important role in the treatment of refractory chronic urticaria and back the hypothesis that an autoimmune/autoreactive mechanism often underlies the disease.
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PMID:Paradoxical exacerbation of chronic urticaria by H1-antihistamines and montelukast. 2012 33