Use this URL to cite or link to this record in EThOS:
Title: Investigations of the physicochemical properties of waxes and wax matrix pellet formulations
Author: Phajongwiriyathorn, Wipapan
ISNI:       0000 0001 3486 8885
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2008
Availability of Full Text:
Access from EThOS:
Access from Institution:
The research resulted in the development of wax matrix pellet systems using a direct warm spheronisation method for use as sustained release devices in oral drug delivery. The effect of altering process parameters on resultant pellet morphology, size distribution and in vitro dissolution performance was evaluated. Changes in the physicochemical and morphological properties of glyceryl monostearate (GMS) and glyceryl palmitostearate (GPS) used in pellet formulations following ageing were monitored by use of FT-IR spectrophotometry, differential scanning calorimetry, hot stage microscopy, X-ray powder diffraction, texture analyses, polarised light microscopy, scanning electron microscopy and dissolution testing. Use of the direct warm spheronisation process resulted in the production of the unstable α-form of GMS that slowly reverted to the stable β-polymorph upon storage at 25°C but GPS exhibited changes in crystallinity upon storage. Thermal annealing of GMS and GPS formulations at 46°C resulted in the melt-solidified GMS (α-form) more rapidly transforming to the stable β-form whereas melt-solidified GPS crystallised faster when compared to 25°C. The thermal annealing cycle at 46°C caused divergent effects in GMS and GPS pellet formulation dissolution performance with decreased drug release rates observed for GMS pellet formulations and increased drug release rates observed for GPS pellet formulations. Moreover, dissolution performance of pellet formulations after annealing was dependent on both wax and drug composition. The inclusions of excipients that stabilised the thermal properties of wax were only effective in preventing modification in pellet dissolution performance for short periods (2 weeks) post-annealing. The combined use of excipients and thermal annealing to stabilise the properties of waxes and provide consistent performance of the delivery device requires further optimisation before it can be a truly useful application for the industrial manufacture of pharmaceutical wax-based oral delivery devices.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral