The surface characterisation of pharmaceutical mini-tablets using thermal probe techniques

Peacock, Joanne (2014) The surface characterisation of pharmaceutical mini-tablets using thermal probe techniques. Doctoral thesis, University of East Anglia.

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This thesis assesses the ability of a range of novel thermo-analytical techniques to determine the spatial distribution of components across the surface of pharmaceutical mini-tablets. Such information is of use in formulation development, as the surface is the point at which a solid dosage form comes into contact with the environment, and where drug stability and excipient functionality are critical. Mini-tablets provide a good model system for surface characterisation, as they have much higher surface area to volume ratios than conventionally sized tablets.
Five excipients and two drugs, as powders and after compaction, were individually characterised by the following techniques: scanning electron microscopy (SEM), variable temperature infrared spectroscopy (VT-IR), differential scanning calorimetry (DSC), atomic force microscopy (AFM), micro-thermal analysis (micro-TA), nano-thermal analysis (nano-TA) and transition temperature microscopy (TTM). Compacts of mixed systems were tested using AFM, micro-TA, nano-TA and TTM, building up the complexity to 4-component systems for excipient-only mixtures and 5-component systems
for drug-loaded mixtures. Micro-TA, nano-TA and TTM were able to detect each component in all of the multi-component compacts, but AFM could not differentiate between them in complex systems. The study was then repeated on realistic mini-tablet formulations, confirming these initial results. Additionally, Raman microspectroscopy was performed on the mini-tablets as a corroborative technique, this method being based on a different physical phenomenon.
In conclusion, the thermal probe techniques (micro-TA, nano-TA and TTM) were shown to be sufficiently discriminating to allow the spatial mapping of components across the surface of realistic mini-tablet formulations. Hence, these techniques could be used alongside spectroscopic techniques in the analysis of complex surfaces. However, some serious issues with the automated analysis and data display functions in the TTM software were identified, which could lead to misinterpretation of the results. Potential corrective measures were suggested to alleviate these concerns and improve experimental reliability.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Pharmacy
Depositing User: Users 2593 not found.
Date Deposited: 26 Nov 2014 16:39
Last Modified: 04 Mar 2015 01:38


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