Controlled release with coating layer of permeable particles.
An enhanced method was proposed for controlled release of core material using a coating layer of fine permeable particles dispersed in an impermeable wax prepared by dry-based process. A mathematical model was constructed to describe in detail the core material release by diffusion through the connected permeable particles inside the coating layer. The effective diffusivity was simulated by a random walk method taking into account the structure of the coating layer. The released characteristics were measured for the urea core particle coated with the layer of the starch permeable particles dispersed in the paraffin wax. The calculated results were in a good quantitative agreement with experimental data in all range of coating conditions. As a result, the low release rate was proven to be obtained with thicker coating layer of lower volume fraction of permeable particles. Moreover, the application of permeable particles instead of soluble ones [J. Chem. Eng. Jpn. 35 (2002) 40] resulted in significant decrease in release rate.
Ito
Ryusei
R
Laboratory of Particulate Engineering, Division of Materials Science and Engineering, Graduate School of Engineering, Hokkaido University, West 8, North 13, Kita-ku, Sapporo 060-8628, Japan.
Golman
Boris
B
Shinohara
Kunio
K
D000465:Algorithms; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D003692:Delayed-Action Preparations / Q000008:administration & dosage / Q000493:pharmacokinetics; D004058:Diffusion; D016503:Drug Delivery Systems / Q000379:methods*; D005079:Excipients / Q000737:chemistry; D008863:Microspheres; D008962:Models, Theoretical; D010232:Paraffin / Q000737:chemistry; D010539:Permeability; D013213:Starch / Q000737:chemistry; D014508:Urea / Q000008:administration & dosage / Q000493:pharmacokinetics*; D014867:Water / Q000737:chemistry
D003692:Delayed-Action Preparations; D005079:Excipients; D014867:Water; C013517:ethyl cellulose; D010232:Paraffin; D014508:Urea; D002482:Cellulose; D013213:Starch