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 C4. Sustained infusion of racemic salbutamol intensified responses to leukotriene C4 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 C4 in animals not exposed to antigen. Ketotifen, but not hydrocortisone, inhibited the enhanced hyperreactivity associated with infusion of racemic salbutamol.