TY  - SER
AU  - Cruz,Pedro Miguel Filipe
AU  - Suwalee Chandrkrachang
AU  - Preeda Pakpian,
AU  - Suwabun Chirachanchai
ED  - Post graduated Studies Program (PTS) European Commission, 
TI  - Chitosan microspheres and beads for the sustained release of theophylline
T2  - Thesis
PY  - 2001///
CY  - Bangkok
PB  - Asian Institute of Technology
KW  - Chitosan
KW  - Theophylline
N1  - 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
N2  - 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.
UR  - http://203.159.5.9/ait-thesis/detail.php?q=B07818
ER  -