Feb 1, 1987

Effect of terfenadine on methacholine-induced bronchoconstriction in asthma

The Journal of Allergy and Clinical Immunology
K R Patel


The dose-response effect of nonsedating H1 histamine-receptor antagonist, terfenadine, administered orally in single doses, was studied on methacholine-induced bronchoconstriction in nine patients with extrinsic bronchial asthma in a double-blind, placebo-controlled, crossover trial. The doses of terfenadine used were 60 mg, 120 mg, and 180 mg, producing small but significant bronchodilator effect with all three doses at 2 hours. This response was still present at 4 hours. However, the provocative dose causing a 20% fall in FEV1 for methacholine was unaffected by all three doses of terfenadine. The bronchodilator response induced by antihistamines, including terfenadine, suggests an increased resting tone mediated by the constant presence of free histamine in the vicinity of H1 receptors in the airways and that methacholine acts directly on the airway muscarinic receptors and is not involved in local histamine release.

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Mentioned in this Paper

Histamine Measurement
Receptors, Histamine H1
Antagonist Muscle Action
Bronchodilator Effect
Bronchodilator Agents
Antihistamines, Classical
Benzhydryl Compounds

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