A comparison of the effects of ketotifen and clemastine on cutaneous and airway reactivity to histamine and allergen in atopic asthmatic subjects.
We compared the effects of ketotifen, a drug with antihistaminic and antianaphylactic properties, with those of clemastine, a conventional H1 antihistamine, on cutaneous and airway reactions to histamine and allergen in atopic asthmatic subjects. Eight subjects received ketotifen, and seven subjects received clemastine, 1 mg twice daily, for two periods of 3 wk. A 2-week interval separated the periods of medication. Maximum expiratory flow rates were measured before and after each treatment period and did not change significantly. Bronchial provocation testing to histamine was performed before and after the first period of medication, and the provocative concentration of histamine required to reduce the forced expiratory volume in 1 sec by 20% from control was increased 4.9-fold by ketotifen (p less than 0.02) and 6.5-fold by clemastine (p less than 0.01). Quantitative histamine and allergen skin testing performed before and after the second period of medication demonstrated significant attenuation of the cutaneous reactions by both medications. Neither medication, however, afforded significant protection against inhaled allergen. Our results suggest that, in the doses used, ketotifen has antihistaminic actions in man equivalent in potency to clemastine but does not appear to have significant additional effects on immediate skin or bronchial responses to allergen.
D000328:Adult; D000403:Airway Resistance / Q000187:drug effects*; D000485:Allergens / Q000494:pharmacology*; D001985:Bronchial Provocation Tests; D002974:Clemastine / Q000627:therapeutic use*; D005260:Female; D006632:Histamine / Q000494:pharmacology*; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000188:drug therapy*; D007665:Ketotifen / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011759:Pyrrolidines / Q000627:therapeutic use*; D012129:Respiratory Function Tests; D012867:Skin / Q000187:drug effects* / Q000276:immunology
D000485:Allergens; D011759:Pyrrolidines; D006632:Histamine; D002974:Clemastine; D007665:Ketotifen