Ketotifen inhibits exacerbation of allergic airway hyperreactivity by racemic salbutamol in the guinea pig

In passively sensitized anesthetized guinea pigs, intravenous infusion of low doses of antigen ovalbumin induced a marked increased responsivity of the airways to intravenous injection of leukotriene C 4. Sustained infusion of racemic salbutamol intensified responses to leukotriene C 4 both before and after infusion of ovalbumin. Hyperreactivity as a result of infusion of ovalbumin was inhibited by intraduodenal injection of either hydrocortisone or ketotifen at doses that did not diminish responses to leukotriene C 4 in animals not exposed to antigen. Ketotifen, but not hydrocortisone, inhibited the enhanced hyperreactivity associated with infusion of racemic salbutamol.