Preparation and release properties of biodegradable chitin microcapsules: II. Sustained release of 6-mercaptopurine from chitin microcapsules

F. L. Mi, Y. C. Tseng, C. T. Chen, S. S. Shyu

Research output: Contribution to journalArticle

7 Citations (Scopus)


Chitin microcapsules are prepared using a simple desolvation or nonsolvent addition phase separation method with 6-mercaptopurine (6-MP) as a reference core. Chitin with a molecular weight about 400 000 is used to prepare different core loaded microcapsules. The drug release rates of chitin microcapsules prepared by simple desolvation or nonsolvent addition method have different release profiles which are related to the rate of phase separation. With respect to the solubility parameter difference (Δδ) value between solvent and nonsolvent, the release rate of 6-MP from microcapsules decreases with increasing Δδ of the preparative system. The chitin beads show poor swelling properties and their release rates are pH-dependent. Sustained release of 6-MP from chitin microcapsules in low pH and neutral medium can be accomplished. To determine if the drug release from the polymer matrix is via a diffusion controlled or by an erosion controlled process, 6-MP release profiles of various chitin microcapsules degraded by lysozyme are investigated. The drug-release patterns of the chitin microcapsules prepared by nonsolvent addition (acetone, n-propanol, n-butanol) and simple desolvation in acetone are not only diffusion but also lysozyme digestion influenced. Whereas, by using water or ethanol as nonsolvent or desolvating agent, release profiles of the microcapsules prepared by nonsolvent addition and the simple desolvation method seem to be little affected by enzyme degradation. These results indicate that chitin might prove useful as a polymer carrier for the sustained release of drugs.

Original languageEnglish
Pages (from-to)211-223
Number of pages13
JournalJournal of Microencapsulation
Issue number2
Publication statusPublished - Mar 1997
Externally publishedYes



  • 6-mercaptopurine
  • Biodegradable
  • Chitin
  • Microcapsule
  • Sustained release

ASJC Scopus subject areas

  • Chemistry (miscellaneous)
  • Pharmaceutical Science
  • Chemical Engineering(all)
  • Pharmacology

Cite this