title: Effects of oral H1 and H2 receptor antagonists in asthma.
abstract: 1 There is evidence that H2 receptors are present in the lung, both on bronchial smooth muscle and mast cells. In animal studies, stimulation of H2 receptors causes a diminution, and conversely H2 receptor blockade can increase, smooth muscle contraction and mediator release. 2 The effects of H2 receptor blockade in ten patients with asthma has been studied using oral cimetidine in a dose of 1 g daily for 1 week. Treatment was compared with placebo and the H1 receptor antagonist chlorpheniramine. 3 There was no alteration in the severity of naturally-occurring or exercise-induced asthma with cimetidine or chlorpheniramine. 4 H2 receptor blockade with oral cimetidine in conventional doses is without ill effect in asthma. The use of larger parenteral doses is discussed.
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D004311:Double-Blind Method; D005540:Forced Expiratory Flow Rates; D006634:Histamine H1 Antagonists / Q000494:pharmacology*; D006635:Histamine H2 Antagonists / Q000494:pharmacology*; D006801:Humans; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D005082:Physical Exertion
chemical_list: D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists