Ketotifen prevents terbutaline-induced down-regulation of beta-adrenoceptors in guinea pig lung.

We examined the effect of ketotifen on the down-regulation of beta-adrenoceptors in guinea pig lung chronically treated with terbutaline. There was a significant decrease in the density of beta-adrenoceptors following chronic administration of terbutaline. Ketotifen prevented the decrease in beta-adrenoceptor density induced by terbutaline in a dose-dependent fashion; ketotifen alone, also increased the density of beta-adrenoceptors. However, neither ketotifen nor terbutaline significantly changed the KD values in either group. These findings suggest that ketotifen might be valuable when beta-agonists are administered for long term treatment in asthmatic patients.