Effects of mometasone furoate on a rat allergic rhinitis model.

The present study was undertaken to clarify the effects of mometasone on nasal symptoms induced by repeated intranasal application of antigen in sensitized rats in comparison with that of chlorpheniramine. Rats received mometasone intranasally or chlorpheniramine orally 1 h before a topical antigen challenge for 7 days. Mometasone caused a decrease in the instances of nasal rubbing and an inhibition of this response was observed during the treatment period. Almost identical findings were observed with chlorpheniramine. This response was inhibited, even after the interruption of mometasone treatment, while such an effect was not observed with chlorpheniramine. On day 36, the changes in sensitivity to histamine were investigated. Unlike chlorpheniramine, hypersensitivity to histamine was significantly reduced in the mometasone-treated group. The passive cutaneous anaphylaxis titers were elevated and reached a maximum 8 days after the start of the topical antigen challenge. The passive cutaneous anaphylaxis titer in the mometasone-treated group was significantly lower than that in the control group. The results indicated that mometasone is effective in allergic rhinitis, not only during the period of application, but also after the interruption of application.