Volume 11, Issue 2 (8-1997)                   Med J Islam Repub Iran 1997 | Back to browse issues page

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BOSKABADY M H, SNASHALL P D. ENHANCED HISTAMINE H I RECEPTOR BLOCKADE WITH CHLORPHENIRAMINE IN THE ASTHMATIC TRACHEO-BRONCHIAL TREE: FURTHER EVIDENCE FOR INCREASED DRUG DELIVERY IN ASTHMA. Med J Islam Repub Iran 1997; 11 (2) :115-122
URL: http://mjiri.iums.ac.ir/article-1-1115-en.html
ENHANCED HISTAMINE H I RECEPTOR BLOCKADE WITH CHLORPHENIRAMINE IN THE ASTHMATIC TRACHEO-BRONCHIAL TREE: FURTHER EVIDENCE FOR INCREASED DRUG DELIVERY IN ASTHMA
MOHAMMAD H. BOSKABADY , PHILLIP D. SNASHALL
From the Department of Physiology, Ghaem Medical Center, Mashhad University of Medical Sciences, Mashhad, Iran
Abstract:   (4934 Views)
We have measured the competitive antagonistic effect of chlorpheniramine in bronchi of 8 normal and 12 asthmatic subjects. Classical pharmacological theory states that the degree of competitive antagonism depends only upon 1) antagonist concentration at the receptor, and 2) receptor affinity. Delivery and affinity also influence agonist responsiveness, but measurement of bronchial antagonism allows study of these factors in isolation. Bronchial responsiveness to histamine was measured as the dose required to produce a 35% fall in specific conductance (sGaw), called PD35• On different days, 2 measurements of control PD35 were made on each subject. Measurements of PD35 were also repeated after inhalation of 1.45 mg chlorpheniramine and intravenous injection of 0.17 mg/kg chlorpheniramine. Antagonist effect of chlorpheniramine was measured as Dose Ratio-l (DR-I), where DR= PD35 after chlorpheniramine/control PD35• Geometric mean of DR -1 with inhaled chlorpheniramine in asthmatic subjects (5.8) was 6.8 times that of normal subjects (0.86) (p= 0.002), and DR-l with intravenous chlorpheniramine in asthmatic subjects (4.4) was 2.75 times that of normal subjects (1.6) (p=0.005). There were significant negative correlations between PD35 and DR-I, whether chlorpheniramine was administered by inhalation (r= -0.87, p
Keywords: histamine HI receptors, asthma, chlorpheniramine, histamine
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Type of Study: Original Research: Basic Science in Medicine | Subject: Physiology
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