Abstract
The effects of betotastine besilate (betotastine: TAU-284), a novel antiallergic drug, on homologous passive cutaneous anaphylaxis (PCA), mediator-induced cutaneous reaction, antigen-induced asthmatic responses and platelet-activating factor (PAF)-induced airway eosinophilia in several animal models, were compared to ketotifen. Betotastine (0.1 mg/kg, p.o.) and ketotifen (1 mg/kg, p.o.) inhibited both rat PCA and histamine-induced cutaneous reaction, whereas they showed little effect on serotonin-induced cutaneous reaction. Betotastine (0.3 mg/kg, p.o.) and ketotifen (1 mg/kg, p.o.) significantly inhibited antigen-induced bronchoconstriction in guinea pigs which had been passively sensitized with guinea pig IgE antibody. In actively sensitized guinea pigs, the immediate and late phase increase in airway resistance (R<sub>rs</sub>) were observed within 5 min and between 4 and 7 h after the aeroantigen challenge. Betotastine (1 mg/kg, p.o.) inhibited both responses. Ketotifen (1 mg/kg, p.o.) inhibited the immediate phase response, but did not affect the late phase response. Exposure of guinea pigs to aerosolized PAF increased the number of eosinophils in bronchoalveolar lavage fluid 24 h after the stimulation. Betotastine (3–10 mg/kg, p.o.) dose-dependently inhibited PAF-induced accumulation of eosinophils in the bronchoalveolar cavity. In contrast, cetirizine (10 mg/kg, p.o.) showed a tendency to inhibit eosinophil accumulation, and ketotifen (10 mg/kg, p.o.) and terfenadine (10 mg/kg, p.o.) did not have any affect. These results indicate that betotastine could be useful in the treatment of allergic disease such as bronchial asthma.
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