The Air Suspension Coating Method To Prepare Sustained-release Pellets

Fluidized-bed technology has been widely used in the research and production of solid preparation because of its unique properties in granulation and coating. It is one of the most common and effective methods in producing sustained-release coating products. The process can be used to apply coating film to the granules and pellets when they are in the state of suspending and fluidizing using airflow by fluidized-bed technology. Although this technology has been developed completely in chemical and engineering field, application in pharmacy has not been studied deeply. To provide the basis for industrial production and raising the level of pharmaceutical products, the coating process variables and the effects of these parameters on the performance of the end products were investigated using self-made air-suspending coater in this article.The paracetamol-loaded pellets were prepared by wet granulating spheronization. The variables were studied by self-made air-suspending coater and optimized as followed: 30 centigrade coating temperature, middle pressure of atomization air and 1.0 mllmin spray rate. The effects of plasticizers, pore-made materials and antiadherents on drug release were investigated using ethylcellulose(EC) ethanol solution as coatingmaterial. The results show that paracetamol sustained-release pellet made3Abstractby 2% EC, 5% diethyl phthalate(DEP), 30% PVP and 1% talc as coating formulation has a good release behaviour.The metronidazole pellets were prepared by a high-speed mixer. It found that the pellets obtained had the advantages of good sphericities high strength and high bulk density. The coating processes were investigated using this method and the optimal parameters of process were found under certain condition, they are 40 centigrade coating temperature, middle pressure of atomization air and 1.0 mi/mm spray rate. The coating of pellets was performed using Surelease ethyl cellulose aqueous dispersion as coating material and different hydrophilic material as the hole-maker. The results indicate that the ideal sustained-release behavior and good release reproductivity are achieved using coating formulation made of 15% Surelease and 30% PVP. The coating mechanism and process with EC aqueous dispersion and organic solvent were compared and the results show that coating process of aqueous dispersion is better than that of organic solvent.The stabilities of metronodazole sustained-release capsules were studied using the method of fit factors. The drug content and release stability of sustained-release capsules were good under the condition of high temperature, high humidity and strong light. The pharmacokinetics of sustained-release capsules in dogs indicates that the Tm~ of capsules is 6h,t112 is 8.17h and the relative bioavailability is 118.79%.The results in this paper show that the coating effect is good and this technology is suitable for the coating of granules and pellets.