Bodmeier R, Wang H, Dixon D J, Mawson S, Johnston K P
College of Pharmacy, University of Texas at Austin 78712, USA.
Pharm Res. 1995 Aug;12(8):1211-7. doi: 10.1023/a:1016276329672.
The objective was to prepare polymeric microparticles by atomizing organic polymer solutions into a spray chamber containing compressed CO2 (PCA-process) and to study the influence of various process parameters on their morphological characteristics.
The swelling of various pharmaceutically acceptable polymers [ethyl cellulose, poly(methyl methacrylate), poly(epsilon-caprolactone), poly(dl-lactide), poly(l-lactide) and poly(dl-lactide-glycolide) copolymers] in CO2 was investigated in order to find polymers which did not agglomerate during the spraying process. Poly(l-lactide) (L-PLA) microparticles were prepared by spraying the organic polymer solution into CO2 in a specially designed spraying apparatus. The effect of various process (pressure and temperature of the CO2 phase, flow rate) and formulation (polymer concentration) variables on the morphology and particle size of L-PLA-microparticles was investigated.
Polymers with low glass transition temperatures agglomerated even at low temperatures. The formation of microparticles was favored at moderate temperatures, low polymer concentrations, high pressures and high flow rates of CO2. High polymer concentrations and low flow rates resulted in the formation of polymeric fibers. Colloidal L-PLA particles could also be prepared with this technique in a surfactant-free environment. Initial studies on the microencapsulation of drugs resulted in low encapsulation efficiencies.
The PCA method is a promising technique for the preparation of drug-containing microparticles. Potential advantages of this method include the flexibility of preparing microparticles of different size and morphology, the elimination of surfactants, the minimization of residual organic solvents, low to moderate processing temperatures and the potential for scale-up.
目标是通过将有机聚合物溶液雾化到含有压缩二氧化碳的喷雾室中（PCA 工艺）来制备聚合物微粒，并研究各种工艺参数对其形态特征的影响。
研究了各种药学上可接受的聚合物[乙基纤维素、聚（甲基丙烯酸甲酯）、聚（ε-己内酯）、聚（dl-丙交酯）、聚（l-丙交酯）和聚（dl-丙交酯-乙交酯）共聚物]在二氧化碳中的溶胀情况，以找到在喷雾过程中不会团聚的聚合物。通过在专门设计的喷雾装置中将有机聚合物溶液喷入二氧化碳中来制备聚（l-丙交酯）（L-PLA）微粒。研究了各种工艺（二氧化碳相的压力和温度、流速）和配方（聚合物浓度）变量对 L-PLA 微粒的形态和粒径的影响。
玻璃化转变温度低的聚合物即使在低温下也会团聚。在适中的温度、低聚合物浓度、高压和高二氧化碳流速下有利于微粒的形成。高聚合物浓度和低流速导致形成聚合物纤维。也可以用这种技术在无表面活性剂的环境中制备胶体 L-PLA 颗粒。对药物微囊化的初步研究导致包封效率较低。
PCA 方法是制备含药微粒的一种有前途的技术。该方法的潜在优点包括制备不同尺寸和形态微粒的灵活性、消除表面活性剂、将残留有机溶剂降至最低、低至中等的加工温度以及放大生产的潜力。
