In vitro modified release of acyclovir from ethyl cellulose microspheres

S. J. Cheu, R. R.L. Chen, P. F. Chen, W. J. Lin

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


The aim of this study was to demonstrate a sustained-release microparticulate dosage form for acyclovir via an in vitro study. Ethyl cellulose was selected as a model encapsulation material. All of the microspheres were prepared by an oil-in-water solvent evaporation technique. A 23 full factorial experiment was applied to study the effects of the viscosity of polymer, polymer/drug ratio, and polymer concentration on the drug encapsulation efficiency and the dissolution characteristics. The encapsulation efficiency of acyclovir in microspheres was in the range of 20.0-56.6%. Increase in the viscosity of ethyl cellulose and the ratio of CH2Cl2/ethyl cellulose increased drug encapsulation efficiency. The drug continuously released from microspheres for at least 12 h, and the release rate depended on the pH of the release medium. The sustained release characteristic was more prominent in the simulated intestine fluid than in the simulated gastric fluid. A faster release of drug was observed when a high viscosity polymer was used. The decomposition of acyclovir significantly decreased when encapsulated by ethyl cellulose, especially when stored at 37 and 50°C.

Original languageEnglish
Pages (from-to)559-565
Number of pages7
JournalJournal of Microencapsulation
Issue number5
Publication statusPublished - Dec 31 2001
Externally publishedYes


  • Acyclovir
  • Ethyl cellulose
  • Microspheres

ASJC Scopus subject areas

  • Bioengineering
  • Pharmaceutical Science
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Colloid and Surface Chemistry


Dive into the research topics of 'In vitro modified release of acyclovir from ethyl cellulose microspheres'. Together they form a unique fingerprint.

Cite this