Freitas Sergio, Merkle Hans Peter, Gander Bruno
Institute of Pharmaceutical Sciences, ETH Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
J Control Release. 2004 Mar 5;95(2):185-95. doi: 10.1016/j.jconrel.2003.11.005.
A novel spray-drying technique consisting of feeding a fluid through an ultrasonic atomiser, drying the spray under reduced pressure and collecting the particles in a liquid bath was evaluated. Drying by mild vacuum instead of hot air, as employed in conventional spray-drying, and simple particle recovery render this method suitable for aseptic microsphere preparation. As a model system, the protein bovine serum albumin (BSA) was encapsulated in poly(lactic-co-glycolic acid) microspheres. Particle yields of above 80% exceeded largely values found for conventional laboratory-scale spray-drying equipment. BSA encapsulation efficiency mostly ranged in the region of 60%, with losses probably occurring through partitioning into the aqueous collection bath. Mean particle sizes ranged from 13 to 24 microm, depending on the polymer type and solvent; particle size distributions were excellently reproducible. The microspheres were found to be very porous and exhibited a pronounced 24-h burst release of above 50% of total dose, probably promoted by the porosity. However, when more concentrated polymer solutions (8% instead of 5% (w/w)) were employed, burst release reduced to an average of 16%.
评估了一种新型喷雾干燥技术，该技术包括通过超声雾化器输送流体、在减压下干燥喷雾并在液浴中收集颗粒。与传统喷雾干燥中使用热风干燥不同，该方法采用温和真空干燥，且颗粒回收简单，使其适用于无菌微球制备。作为模型系统，将蛋白质牛血清白蛋白（BSA）封装在聚（乳酸 - 乙醇酸）微球中。颗粒产率超过80%，大大高于传统实验室规模喷雾干燥设备的产率。BSA包封效率大多在60%左右，损失可能是由于分配到水性收集浴中。平均粒径范围为13至24微米，具体取决于聚合物类型和溶剂；粒径分布具有出色的可重复性。发现微球孔隙率很高，并且表现出明显的24小时突释，超过总剂量的50%，这可能是由孔隙率促进的。然而，当使用更浓的聚合物溶液（8%而不是5%（w/w））时，突释平均降至16%。
