Objective: To prepare betaxolol hydrochloride-montmorillonite ion exchange microspheres eye suspension. Method: Excipients of betaxolol hydrochloride-montmorillonite ion exchange microspheres eye suspension were screened and its preparation characters were evaluated

biological properties of microspheres suspension were investigated by eye irritation and isolated corneal permeability test. Result: Optimal combination was 0.15% carbomer 934P as suspending agent and 0.01% tween-80 as wetting agent.Its stability

pH value

osmotic pressure

viscosity and corneal irritation were complies with the requirement of ophthalmic preparations applications.During irritation test

there was no obviously irritating in the microspheres suspension group

but the Beiteshu group's conjunctiva appeared partly lymphocytic infiltrates.Isolated corneal permeability test showed that the suspension's apparent permeability coefficient (Papp) was 1.78×10-5 cm·s-1

half of betaxolol hydrochloric solution (3.57×10-5 cm·s-1) and twice of Beiteshu drops (0.85×10-5 cm·s-1). Conclusion: It is shows that self-made ion exchange microspheres suspension possesses capability of sustained-release and extenuate drug toxicity.