Thesis

Biodegradable microspheres for drug delivery

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Awarding institution
  • University of Strathclyde
Date of award
  • 1998
Thesis identifier
  • T9555
Qualification Level
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Department, School or Faculty
Abstract
  • The use of microspheres in drug delivery systems is one of the strategies that represents technologies which have made improvements in the pharmacokinetic and pharmacodynamics of therapeutic agents. This research is aimed at the preparation and characterization of three different types of biodegradable microsphere: poly (d,l lactide- co-glycolide) (PLGA), hyaluronic acid (HA) and cross-linked HA microspheres. Dexamethasone was the drug used in this study with its potential application in delivery to the brain and colon. The method used for the microsphere preparation was an emulsification solvent evaporation technique. PLGA and HA microspheres were characterized in terms of particle size, drug content and in vitro drug release. The results of particle size analysis showed an average size range of 2-5gm for PLGA microspheres. HA microspheres were in the range of 21-23 gm. The difference in particle size range for PLGA and HA microspheres was due to the different mixing speed and polymer viscosity. Light microscopy results showed spherical microspheres for PLGA and HA, consistent with the laser diffractometry results. The level of dexamethasone in HA and PLGA microsphere was 73.5% and 15.5%, respectively. The in-vitro release pattern in phosphate buffer saline at 37°C over 200hrs showed a burst release followed by a slower sustained release of 30% (PLGA microspheres) and 12% (HA microspheres). HA microspheres swelled in water due to hydration. The last part of the project involved modification of HA microspheres using cystine methyl ester and carbodiimide as cross linking agents in order to improve HA microsphere stability. Clear, spherical, cross linked HA microspheres were obtained with a size range of 60-70gm which appeared to be more stable.
Advisor / supervisor
  • Whateley, T. L.
  • Eccleston, G. M.
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