Controlled release with coating layer of permeable particles

Ryusei Ito, Boris Golman, Kunio Shinohara

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)361-368
Number of pages8
JournalJournal of Controlled Release
Issue number3
Publication statusPublished - Oct 30 2003


  • Coating layer
  • Controlled release
  • Mathematical model
  • Permeable particles
  • Random walk simulation

ASJC Scopus subject areas

  • Pharmaceutical Science

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