Preparation method of timolol maleate sustained release microspheres

The invention discloses a preparation method of timolol maleate sustained release microspheres. The preparation method comprises the following steps: by adopting an oil-in-oil technology, preparing an internal phase from timolol maleate, modified montmorillonite, acrylic resin, tween and a plasticizer and preparing an external phase from vegetable oil and span; carrying out ultrasonic treatment on an obtained oil-in-oil emulsion; then, electromagnetically stirring to evaporate the internal phase to obtain the timolol maleate sustained release microspheres. The grain diameter of the timolol maleate sustained release microspheres can be controlled in a range of 10 mu m, so that the demand of eye-drops preparations is met. The medicine encapsulation rate reaches up to 80-99%, and the in vitro releasing time can be prolonged to 10-12 hours. The timolol maleate sustained release microspheres prepared by the method serving as an ocular hypotensive agent can reduce intraocular discomfort and reduce the medication fr