Immunopharmacology and inflammationOlopatadine hydrochloride suppresses hot flashes induced by topical treatment with tacrolimus ointment in rats

Tacrolimus ointment is prescribed for patients with atopic dermatitis, although it is known to cause transient burning sensations and hot flashes in the applied skin. The aim of this study was to evaluate the effects of olopatadine hydrochloride (olopatadine), an antiallergic agent with a histamine H1 receptor (H1R) antagonistic activity, on the incidence of hot flashes induced by topical treatment with tacrolimus ointment in rats. Consequently, the skin temperature was increased by the topical application of tacrolimus ointment in rats, and the rise in skin temperature was inhibited by pretreatment with olopatadine in a dose-dependent manner. Inhibitory effect of olopatadine on tacrolimus-induced skin temperature elevation was significantly more potent than that of cetirizine hydrochloride, other antiallergic agent with H1R antagonistic activity, at doses in which both agents exhibit comparable H1R antagonistic activity in rats. These results suggest that H1R antagonistic activity-independent mechanism contribute to the inhibitory effect of olopatadine on tacrolimus-induced skin temperature elevation. Olopatadine also significantly inhibited increases in vascular permeability and nerve growth factor production in the skin induced by topical tacrolimus treatment. Thus, the onset of hot flashes in rats is quantitatively determined by measuring the skin temperature and olopatadine attenuates hot flashes induced by topical tacrolimus ointment in rats, suggesting that the combination application with olopatadine and tacrolimus ointment is useful for improving medication adherence with tacrolimus ointment treatment in patients with atopic dermatitis.