Chitosan microspheres and beads for the sustained release of theophylline
- Bangkok : Asian Institute of Technology, 2001
- 66 leaves
- Thesis ; no. BP-01-01 .
- Asian Institute of Technology. Thesis ; no. BP-01-01 .
A thesis submitted in pa1iial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development
Thesis (M.Sc.) - Asian Institute of Technology, 2001
The main purpose of this study was to develop a sustained delivery system based on the0phylline containing chitosan microspheres obtained by an optimized spray drying technique. Theophylline is an extensively used bronchodilator with a half-life of 5 hours. Due to its narrow therapeutic levels, it should be applied preferentially in a well-controlled delivery system. The spray drier LabPlant SD-05 was used to microencapsulate the theophylline into a chitosan microspheres. Several operational parameters and theophylline: chitosan ratios were investigated in order to establish a correlation with the dissolution characteristics and loading efficiency. Spherical chitosan microspheres loaded with theophylline were about 5 æm in diameter. It was found that a lower chitosan concentration (0.5% w/v) and theophylline: chitosan ratio (20% w/w) resulted in the best loading efficiency and sustained release. This suggests a more effective heat and mass transfer and therefore better drying conditions for proper entrapment of the drug. Additionally chitosan beads loaded with theophylline were prepared by ionotropic gelation technique: dropping chitosan/theophylline solution into a coagulation bath of penta-sodium tripolyphosphate (TPP). A very low total release, dependent on the theophylline content, was attained, likely due to the agglomeration of the beads under the conditions used.