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Title: The evaluation of in vivo release rates of pharmaceutical preparations
Author: Stewart, Frances
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 1992
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Traditional methods for the assessment of drug delivery concentrate on the analysis of the absorption process, however, more recent techniques have enabled the actual release rates of the drugs to be determined. Direct evaluation of the release rate in vivo is not practical, as such an approach would be excessively invasive, therefore information about the in vivo release process must come from the manipulation of other data. Two methods in particular (Maximum Entropy and Deconvolution) have the ability to provide information about the whole time course of release and can separate the in vivo release process from that of absorption. The Maximum Entropy approach and various deconvolution algorithms were examined for stability to data noise and their ability to predict correctly both the form and values of unknown release rates. This examination was made using pseudo-experimental data, so that the true form of the unknown release rate was known prior to analysis, and using clinical data arising from the administration of controlled release metoprolol tablets. A comparison was made of all the methods tested to find the optimal method for the assessment of in vivo release. The results obtained showed that no one method is optimal for all aspects of the assessment of drug release, but that the method of choice is dependent on the information required. The Maximum Entropy method was shown to be preferred when the aim of the assessment was the study of the in vivo release rate as a function of time. However, if a less in depth assessment is required (eg the calculation of MDT or the fraction of dose released vs time) then there was no advantage shown to the use of the more complex methods and one of the simpler deconvolution algorithms becomes the method of choice.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available