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Title: NMR studies and modelling of a controlled release pharmaceutical delivery system
Author: Collins, J. H. P.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2008
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A multiparticulate controlled release drug delivery formulation has been studied using nuclear magnetic resonance (NMR) techniques. The experimental data has been used to construct a numerical model, which can be used to predict the drug release characteristics of the formulation. Finally, magnetic resonance imaging (MRI) has been used to confirm measurements of liquid absorption into a polymeric matrix conducted using Terahertz time-domain spectroscopy. NMR relaxation measurements were combined with PFG diffusion measurements in order to detail the evolution of pore size distribution (PSD), tortuosity, and surface to volume (S/V) ratio of the pore network, for a range of different formulations at increasing immersion times in water. The results clearly show a decrease in the effective tortuosity and S/V ratio with increasing immersion time in all formulations studied. The PSD’s show a corresponding increase in average pore size, as well as changes in the distribution of pore sizes, particularly in the drug-loaded formulations. Coated formulations show a significant differences in the pore structure evolution, compared to the uncoated formulations. Magnetic resonance images of the formulations have been used to calculate the water absorption rates. Studies have been conducted at both room temperature and 37°C. The water uptake properties were found to vary significantly between the different formulations studied. NMR experiments conducted on a formulation loaded with a fluorine compound were also used to calculate the specific dissolution rate of the compound. The results from these experiments were used as parameters in the developed numerical model, which can predict the drug release characteristics. The model predicts the drug release rate of several different formulations with reasonable accuracy. This model has also been used to make several predictions regarding how altering the formulation will affect the drug release properties.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available