Cruz, Pedro Miguel Filipe creator Suwalee Chandrkrachang Chairperson Preeda Pakpian Examination Committee Suwabun Chirachanchai Examination committee Post graduated Studies Program (PTS) European Commission Scholarship donor text series technical report th Bangkok Asian Institute of Technology 2001 continuing eng 66 leaves 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. 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 Chitosan Theophylline Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B07818 http://203.159.5.9/ait-thesis/detail.php?q=B07818 200717 20260817172702.0