Preparation Of Alginate Microcapsules And Drug Release From Coating-membrane And Floating Microcapsules

In this work, we developed laser-drilling plate and sapphire stone plate as spray nozzle and made alginate microcapsules by capillary vibration apparatus. Using Cefaclor (CF) and Nimodipine (NMP) as release drug, alginate-chitosan floating extended-release microcapsules and alginate-ethyliccellulose(EC) floating extended-release microcapsules were produced by freezing dry method and bubble method respectively. Results as follows: Using needle with different diameter as the sprayer, the influence of spray speed and vibration frequency on microcapsules size and standard deviation (SD)were reviewed. The experimental result indicated that microcapsules size decrease with the enhance of vibration frequency and increase with the raise of spray speed or needle diameter. It was demonstrated from calculated data of theory that selection of optimum operating frequency according to Weber theory is adoptable, especially when system used large diameter needle. Sprayer with laser-drilling plate or red stone plate possessed many advantages such as low pressure requirement, large quantity, difficult to jam, low SD and suitable industrial use. Microcapsules got from multi-nozzle red stone plate and single hole plate have similar size distribution, which shows multi-nozzle is practicable. The bellows agitation apparatus with 16 nozzles reached to 14 L/h yield. Alginate-chitosan floating extended release microcapsules by freezing-dry method was not applicable for CF delivery, while suitable for NMP. It was demonstrated by SEM that CF was mainly distributed the surface layer of microcapsule coated chitosan membrane. The structure of microcapsule becomes much more uniform after adding of konjac glucomannan. NMP microcapsules have smooth surface thicker membrane after adding of NaHCO3. Alginate-EC floating extended release microcapsules by bubbled method was applicable for CF release system. The microcapsules with three times coating membrane appeared the best controlled release capabilities. The release rate for different system was not susceptible to calcium ion concentration. Proper KGM concentration (0.25%) can keep sphere shape and meet constant release rate. It was indicated by release mechanism that the EC membrane was the key parameter. Above all, the equipment and method of preparing alginate microcapsules was established. Comparing the freezing dry method, the babble method was relatively simple. Whether chitosan membrane or EC membrane was selected should concern the specific drug.