Abstract: AIM: To evaluate the antihistamine effects of domestic azelastine hydrochloride. METHODS: Histamine increased skin vascular permeability and induced shock model in guinea pigs.In isolated guinea pig ileal rings, the contraction of smooth muscle induced by histamine was determined. RESULTS: Pretreament with azelastine hydrochloride(0.05, 0.15, and 0.45 mg·kg^-1,ig) significantly inhibited the increase in skin vascular permeability induced by histamine in a dose-dependent manner in guinea pigs.Pretreament with azelastine hydrochloride(0.05, 0.1, and 0.2 mg·kg^-1, ig) produced a significant improvement of shock, as shown by a decrease in reactivity degree, mortality and a prolongation of latency.In isolated guinea pig ileal rings, azelastine hydrochloride (10^-8, 3 ×10^-8, 10^-7, 3 ×10^-7mol·L^-1) significantly inhibited contraction of smooth muscle induced by histamine in a concentration-dependent manner and caused a parallel right shift of the dose-effect curve of histamine (pA₂=8.55). CONCLUSION: Domestic azelastine hydrochloride shows significant the antihistamine effects.

Key words: azelastine hydrochloride, histamine phosphate, shock, vascular permeability, isolated ileal rings, guinea pigs