Epinastine is a potent
antiallergic agent that has not only antihistaminic (H(1)) properties but also provides antileukotriene, anti-PAF and antibradykinin activities, which are associated with its
antiallergic actions. Moreover,
epinastine is very effective in inhibiting the release of chemical mediators from mast cells exposed to
antigen. In addition,
IL-8 release from eosinophils was inhibited by
epinastine posttranscriptionally. Chemotatic movement of eosinophils was also blocked by
epinastine. The increase in EEG power spectrum at low frequency region detected at frontal cortex is associated with drowsiness. No such change was induced by
epinastine, while a marked increase was observed after
ketotifen. In agreement with this, when the amount of H(1) blockers that penetrated through the BBB into the brain was estimated by means of PET, it was apparent that
epinastine hardly penetrated the BBB. With regard to the current-voltage relationship of HERG currents,
epinastine did not affect I(Kr), while a marked inhibition was seen after
terfenadine or
astemizole. These results indicated that
epinastine does not suppress delayed rectifier
potassium current of the heart and, consequently, no cardiotoxic action of
epinastine was postulated. In man,
epinastine is readily absorbed after
oral administration and no significant change in pharmacokinetics was found during chronic administration. In teratological studies in rats, malformation and variation were not observed even at high doses of
epinastine. In the clinical application of
epinastine, it was shown that this
drug is remarkably effective in the treatment of various dermatological diseases, such as
chronic urticaria,
psoriasis vulgaris and other pruritic
dermatoses. Moreover,
epinastine provides excellent clinical efficacy in the treatment of
allergic rhinitis. Although efficacy of H(1) blockers in
bronchial asthma is somewhat doubtful, the overall improvement rate in asthmatic patients was significantly higher in
epinastine-treated patients (53.7%) compared to those treated with
ketotifen (25%).