One continuous process of agglomeration and microencapsulation for enoxacin. Preparation method and mechanism of microencapsulation

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Abstract
A novel microencapsulation method was developed by using the wet spherical agglomeration (WSA) technique. Spherical agglomerates containing enoxacin (ENX) or lactose were prepared in the acetone-n-hexane-ammonia water (or distilled water) solvent system, and were microencapsulated continuously with the aminoalkylmethacrylate copolymer (Eudragit RS). Microencapsulation was performed with a modified organic phase separation by the non-solvent addition method. By selecting proper composition ratio of acetone and n-hexane, the WSA solvent system turned to a non-solvent for a wall material, i.e. Eudragit RS. Dichloromethane was used as a good solvent because it did not affect the characteristics of spherical agglomerates prepared in the WSA system. With this technique the Eudragit RS coacervate droplets were firstly generated in the solvent composed of a higher acetone volume ratio in the acetone/n-hexane mixture, and continuously the coacervate droplets were deposited efficiently onto the agglomerates by adding additional n-hexane into the system. Spherical microcapsules with the size ranged between 100 and 1000 microns, were successfully produced owing to the spherical shape of agglomerates containing ENX or lactose.