Abstract
BACKGROUND: Olopatadine hydrochloride (olopatadine), a histamine H(1) receptor antagonist, inhibits release of substance P (SP) from peripheral nerve endings. It has antiallergic effects and is widely used in dermatology and otolaryngology. It is known that the SP concentration is significantly higher in the nasal secretions of patients with allergic rhinitis than in those of healthy individuals, suggesting a relationship between SP concentrations in nasal secretions and symptoms. AIM: To investigate effects of olopatadine on SP concentrations in nasal secretions of patients with cedar pollinosis and their relationship with symptoms. METHODS: Nasal secretions were collected before and after administration of olopatadine to 12 Japanese patients with cedar pollinosis. SP concentrations in nasal secretions were measured and their relationship with scores for nasal symptoms evaluated. RESULTS: After administration of olopatadine, sneezing, rhinorrhea and severity of symptoms improved significantly (all P < 0.05) and SP concentrations in nasal discharge were significantly lower than before treatment. Our findings suggest that symptoms improve when SP concentrations in nasal secretions decrease. It has been reported that patients with allergic rhinitis have significantly higher concentrations of SP in nasal secretions than healthy individuals, suggesting the importance of controlling SP concentrations when treating allergies. CONCLUSION: Olopatadine suppresses release of SP, which is involved in itching and inflammation. Our findings suggest that its administration may prove to be a useful new strategy for treating allergies.