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Mepyramine The first effective and safe antihistamine.

H 1 Antihistamines & Urticaria Dr.M.Al.Ahmad , De r matologist Homs Military Hospital 21.4.2009.

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Mepyramine The first effective and safe antihistamine.

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  1. H1 Antihistamines & UrticariaDr.M.Al.Ahmad ,DermatologistHoms Military Hospital21.4.2009

  2. Histamine is a small molecule derived from the decarboxylation of the amino acid histidine. It is destroyed by the enzyme diamine oxidase (histiminase), which is also involved in the metabolism of other bioactive amines.

  3. Mepyramine The first effective and safe antihistamine. Was discovered in 1944 by Parisian investigators ,Bovet and walthert.

  4. Classification First- generation H1 antihistamines. (Sedating-H1 antihistamines). Second-generation H1 antihistamines. (None-sedating H1 antihistamines)

  5. First-generation H1 antihistamines. Potent effect. Short- acting. Metabolized in liver by the microsomal cytochrome P-450 system.

  6. First- generation H1 antihistamines Common side effects: Sedation. Atropine like side effects: -Dryness of the mouth . -Blurring of vision. -Constipation. -Urinary retention.

  7. Others: Photosensitivity. Tachycardia. Prolongation of the Q-T interval.

  8. Second generation-H1antihistamines No or low sedation when recommended doses are used. No anticholenergic side effects. Long- acting. No drug interaction. No cardiac side effects.

  9. Novel second- generation H1 antihistamines. -Rupatadine. -Bilastine.

  10. H1 antihistamines in children Second generation ones are probably safer. - Overdose of the fist generation may cause severe toxicity including hyperpyrexia and convulsion. -First-generation ones might cause paradoxical excitation in children.

  11. Indications Hypersensitivity reactions type one: Perennial or seasonal allergic rhinitis. Vasomotor rhinitis. Allergic conjunctivitis. Urticaria.

  12. Urticaria (Hives) Prevalence: (adult and children ): Acute : 15 – 25 % lifetime prevalence . Chronic idiopathic : Up to 5 % of population. 20% of these have symptoms >10 years.

  13. Acute urticaria -symptoms present for <6 weeks -More common in Young's -More common in atopic vs non atopic

  14. Chronic urticaria - Symptoms continuously or intermittently present for> 6 weeks. -6 weeks is not an absolute demarcation. -Female : male : 4 : 1 -No increase in incidence in atopics.

  15. Causes Allergic : Food. -Food additive / preservatives. Drugs. Others: (venom, latex… ).

  16. Infections : viral parasitic. Questionable :(H-pylori, sinusitis ,others )

  17. Non – allergic release of histamines: Drugs : -Aspirin. - ACE inhibitors. Narcotics. Radiocntrast media.

  18. Systemic illnesses/ conditions: Complememt deficiencies. Cryoglobulinemia serum sickness. Rhumatological.

  19. Idiopathic More than 50% of cases.

  20. Pharmacological treatment First line : -Non – sedating H1 antihistamines . Double the dose if not responding. - Sedating H1 antihistamines at night.

  21. Results: 12 items · 1. Quality of life in adults with chronic idiopathic urticaria receiving desloratadine: a randomized, double-blind, multicentre, placebo-controlled study.Grob JJ, Auquier P, Dreyfus I, Ortonne JP.J Eur Acad Dermatol Venereol; 2008 Jan ; 22(1):87-93. PubMed ID: 18181978[Abstract] [Full Text] [Related] · 2. Increasing the dose of cetirizine may lead to better control of chronic idiopathic urticaria: an open study of 21 patients.Kameyoshi Y, Tanaka T, Mihara S, Takahagi S, Niimi N, Hide M.Br J Dermatol; 2007 Oct ; 157(4):803-4. PubMed ID: 17627798[No Abstract] [Full Text] [Related] · 3. The effect of fexofenadine hydrochloride on productivity and quality of life in patients with chronic idiopathic urticaria.Spector SL, Shikiar R, Harding G, Meeves S, Leahy MJ.Cutis; 2007 Feb ; 79(2):157-62. PubMed ID: 17388220[Abstract] [Full Text] [Related] · 4. Efficacy and safety of desloratadine in adults with chronic idiopathic urticaria: a randomized, double-blind, placebo-controlled, multicenter trial.Ortonne JP, Grob JJ, Auquier P, Dreyfus I.Am J Clin Dermatol; 2007 ; 8(1):37-42. PubMed ID: 17298105[Abstract] [Full Text] [Related] · 5. Levocetirizine is an effective treatment in patients suffering from chronic idiopathic urticaria: a randomized, double-blind, placebo-controlled, parallel, multicenter study.Kapp A, Pichler WJ.Int J Dermatol; 2006 Apr ; 45(4):469-74. PubMed ID: 16650180[Abstract] [Full Text] [Related]

  22. THANK YOU

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