The effect of azelastine and some other antiasthmatic and antiallergic drugs on calmodulin and protein kinase C

The antiallergic and antiasthmatic drug, azelastine, interacts strongly with calmodulin (but not bovine serum albumin) as determined by an indirect assay; it also moderately inhibited the Ca²⁺-calmodulindependent enzyme bovine brain phosphodiesterase. Ketotifen was less active than azelastine in both assays of calmodulin reactivity and both drugs were less active than the recognized calmodulin inhibitor, W-7. Neither azelastine nor ketotifen had any inhibitory effect on the Ca²⁺- and phospholipid-dependent protein kinase C. A number of other commonly employed antiallergic and antiasthmatic drugs were essentially inactive in the calmodulin assays and had no or marginal inhibitory effect on protein kinase C.