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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Discovery and evaluation of anti-cancer agents

Lam, Fong Ki January 2010 (has links)
Cancer is the most common cause of the human death in the UK. Every year 3.2 million Europeans are diagnosed with cancer, and the figure is projected to rise due to the aging population. Although significant advances are being made in the fight against the disease, cancer remains a key public health concern and a tremendous burden on UK society in financial and social terms. This thesis evaluated two classes of compounds that can be potentially developed as anti-cancer agents. 4-(4-Methyl-2-(methylamino)thiazol-5-yl)-2-(4-methyl-3-(morpholinosulfonyl)phenylamino)pyrimidine-5-carbonitrile (S-134, 5g) is a novel cyclin-dependent kinase 9 (CDK9) inhibitor showing nano-molar growth inhibitory potentials in established human cell lines. Biochemical assays have confirmed that S-134 primarily inhibits CDK9 at the protein and cellular levels, respectively. The detailed mechanistic investigation demonstrated that the compound caused wild-type p53 stabilisation and cell cycle arrest at the G2/M transition. Cancer cell death induced by S-134 was proven by Annexin-V/PI staining, caspase-3 assay and PARP cleavage. Transcription and expression of anti-apoptotic proteins Mcl-1, Bcl-2 and XIAP were reduced by the inhibitor, as proved by RT-PCR and Western blots respectively. Compound 2-methoxy-5-(3,4,5-trimethoxyphenethyl)phenyl 2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrole-3-carboxylate-N-oxide (ZJU-6, 6g) a semi-synthetic derivative of the natural medicinal compound Erianin (6a) was designed to introduce anti-oxidant property and enhance anti-angiogenic activity of Erianin. The study of ZJU-6 revealed that while the effect of cellular growth inhibition and the transcription of Bcl-2 were reduced by the structural modification, the suppression of tubulin polymerisation and anti-angiogenic properties were enhanced compared to Erianin. Compound BI 2536, 4-(8-cyclopentyl-7-ethyl-5-methyl-6-oxo-5,6,7,8-tetrahydropteridin-2-ylamino)-3-methoxy-N-(1-methylpiperidin-4-yl)benzamide (10), is one of the most potent and selective inhibitors of Polo-like kinase 1 (Plk1) and is a current experimental candidate for the treatment of cancer. A racemic BI 2536 was synthesised using multiple synthesis routes, which aimed to use as a lead compound for the discovery of novel Plk1 inhibitors.
102

Increasing drug retention in lung tissue through conjugation with polyethylene-glycol

Bayard, Fabrice J. C. January 2013 (has links)
The pulmonary delivery of drugs is an attractive route of administration because of the large surface area and high permeability of the airway epithelium. The large majority of inhaled drugs are used to manage asthma and Chronic Obstructive Pulmonary Disorder (COPD), such as inhaled corticosteroids and β2-adrenergic receptor agonists. Local delivery of small molecules often results in sub-optimal pharmacokinetics characterised by short absorption times (tmax) and high systemic concentrations (Cmax). Numerous drug delivery strategies have been attempted to increase lung retention time, including drug encapsulation in microspheres, the use of polymeric excipients, or the formation of low solubility drugs. So far, drug conjugation strategies have been limited to decreasing the prodrug solubility. The non-permanent conjugation of small molecules to a large hydrophilic polymer has not been studied for pulmonary delivery. The rationale behind such a strategy is that small molecules are mainly absorbed through the epithelium by passive diffusion, the absorption rates being positively correlated to the drug lipophilicity and molecular weight. This project has therefore been looking at the production, characterisation, in vitro and ex vivo evaluation of polyethylene glycol (PEG)-ester conjugates for the sustained delivery of drugs to the lung. This thesis presents the successful oxidation and subsequent esterification of PEG of various molecular weights with prednisolone (a corticosteroid) and salbutamol (a β2-adrenergic receptor agonist). This study illustrated the feasibility of a polymeric drug conjugate strategy for sustained release of drugs to the lung. The conjugates exhibited good in vitro stability which was translated into improved pharmacokinetics and longer residence time ex vivo in the isolated and perfused rat lung. Further studies must be conducted to fully assess the role of esterases in the pulmonary hydrolysis of the conjugates and in vivo experiments would be necessary to verify the safety of the conjugates and efficacy of the drug.
103

Time of flight mass spectrometry of pharmaceutical systems

Armitage Nolan, Jennifer Claire January 2013 (has links)
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a widely used surface chemical analysis technique that is traditionally employed to characterise the first few molecular layers of a material interface. The ability of this technique to accurately reflect the surface chemistry of polymers, biomaterials and many other solid materials is well documented. However, the majority of research that utilises this technique is based upon a qualitative rather than quantitative assessment of the material under investigation. The qualitative analysis of a range of traditional tablet and bead formulations containing drug and multiple excipients was performed in order to identify key diagnostic ions for all the different components. The lateral distributions of the ions across the surfaces of these formulations were imaged. Two different methods were then used to perform a qualitative analysis of the surfaces and results from these experiments were compared to the bulk composition. The effect of surface roughness on the ability to produce reproducible quantitative analyses from ToF SIMS ion yield data was investigated. A range of samples with different topographies were studied including polytetrafluoroethylene (PTFE), glass microscope slides, gold coated abrasive papers and gold coated precision measurement samples. The surface roughness was assessed by Atomic Force Microscopy and Laser Profilometry. Samples were analysed in imaging mode and the variance in ionization across the total image was measured for each sample. Evidence is presented that there is a relationship between ion yield and surface roughness, and that the surface roughness of the analysed surfaces will effect on any quantification approach in the processing of ToF-SIMS data. In addition, the presence of any orientation/directionality in surface features also needs to be evaluated when considering use of a quantitative approach. To investigate the effect of chemical environment on the ability to derive quantitative data from ToF SIMS analysis of pharmaceutical materials, drug loaded spun cast polymer films with low surface roughness were studied. ToF SIMS data were obtained for two chemically similar drugs in two different polymer matrices. In the majority of the samples there was no quantitative relationship between drug ion intensity and nominal bulk composition. Due to the large sample set, the multivariate technique, Principal Component Analysis (PCA) was employed to look at variance in secondary ion yields from the different samples. PCA is becoming more prevalent in ToF-SIMS data interrogation as it allows for a mathematically un-biased analysis of sample variables through the identification of the ions that account for the majority of the variance in the sample set. PCA successfully highlighted the impact of the chemical environment, showing secondary ion yields of drugs can be dependent on the surrounding matrix. PCA was also used to look at variance in two of the tablet samples and was successfully able to differentiate between the tablet samples with the lowest and highest concentrations of paracetamol. This thesis has demonstrated that surface topography and surface chemical environment or matrix will have a significant impact on ion yields in the ToF-SIMS experiments. These findings suggest caution in the use of ToF-SIMS for the quantitative analysis of complex chemically heterogeneous and topographically diverse pharmaceutical formulations.
104

An exploration of pharmacists' learning in practice

Gifford, Alison Jane January 2008 (has links)
Informal learning is a major factor influencing the professional development and practices of health professionals (Eraut, 1994). This thesis is an in-depth exploration of how this process occurs in pharmacy and involves a detailed study of practising pharmacists. The learning approach of these individuals is explored in relation to the variety of working situations in which they practise and the prevailing climate in relation to professional learning and development within the National Health Service (NHS). This study therefore adds to an understanding of the way in which informal learning shapes the practice of pharmacists and as such it has considerable implications for both future policy and practice. In the past there has been very little detailed research investigation into informal learning in pharmacy, although studies by Wilson, Schlapp & Davidson (2003) and Swallow et al (2006) have demonstrated the importance of this aspect of professional development. This study addresses that deficit, utilising semi structured interviews and focus groups to explore in some depth the nature of pharmacists’ informal learning and their perceptions of the effectiveness of current CPD practices in supporting such learning. The study reveals that pharmacists use a range of informal learning methods to develop in their careers post-qualification, including experiential learning and reflective practice. Many also continue to take further formal courses and qualifications. Practitioners perceive knowledge to be of particularly high value, and place less emphasis and value on the learning of skills, attitudes and behaviours, despite their comprising a vital part of practice. The role of helpful others (Eraut et al., 2004) plays a critical part in the professional learning and development of many pharmacists. They appear to value this support highly and in some cases rely on it due to the isolated nature of their practice situation. Paradoxically, whilst pharmacists acknowledge the need to provide evidence of their ongoing professional development, they often do not complete CPD records in practice. One of the main criticisms offered, in relation to the CPD system, was the perceived limitations of the RPSGB Plan & Record forms, and this was also used as a justification for not completing their records. Greater flexibility in the system was seen as vital for the full benefits and strengths of the CPD system to be realised. The change management process through which the RPSGB introduced CPD is critically examined and the literature on educational change processes utilised, to suggest ways in which the implementation process of CPD may have created the resistance evident in the pharmacists’ narratives. This thesis raises questions about the value that pharmacists and the pharmacy profession place on various types of learning. The importance of informal learning in the development of pharmacists is emphasised. The thesis also explores the apparent need for pharmacists to have access to appropriate helpful others and the need to ensure that the method used to record CPD is flexible and fit for purpose.
105

Toward advanced modular drug and gene delivery system

Saeed, Aram Omer January 2010 (has links)
In chapter two, the development of new a nanoparticulate carrier system for gene delivery was described. The new nanocarrier consists of a blend matrix formed by a poly (lactic-eo-glycolic acid) (PLGA) and Poly(ethylene glycol) bis (3-aminopropyl) terminated (also known as JeffamineTM). Nanopartic1es were formulated based on a 50:50 weight ratio of PLGA:Jeffamine using a modified emulsification-solvent diffusion technique. The potential of these blended matrix nanoparticles for encapsulation efficiency of Calf Thymus DNA and release profile were also studied. The achieved encapsulation efficiency of Calf Thymus DNA was approximately 84% for 0.4% theoretical loading with regard to total amount of PLGA. The PLGA: Jeffamine blended nanoparticles provided continuous and controlled release of Calf Thymus DNA. The PLGA:Jeffamine nanopartic1es were also coated with PLGA-PEGMA&75and PDMAEMA-PEGMA block copolymers using a simple physical adsorption method. After surface coating of the nanoparticles, zeta potential value showed significant reduction of surface charges from -38 mV to near zero value, while TEM micrographs showed a well defined core-shell nanoparticle. In chapter three, A facile route to biocompatible poly (lactic acid-coglycolic acid)-co-poly (ethyleneglycol methacrylate) (PLGA-PEGMA) block co-polymers was described utilising a combination of ring-opening polymerisation (ROP) and Radical Addition Fragmentation Transfer (RAFT) methods. A series of PLGA-PEGMA polymers varying in comonomer content and block length were synthesised with low polydispersities. All the block co-polymers formed micelles in aqueous solution as shown by dynamic light scattering, while critical micelle concentrations were found to be in the micromolar range. The polymer micelles were able to encapsulate model drugs(carboxyfluorescein and fluorescein isothiocyanate) and selected copolymer micelles incubated with 3T3 fibroblasts as a model cell line were rapidly taken up as indicated by fluorescence microscopy assays. The combination of the polymer chemistries opens the way to highly flexible syntheses of micellar drug carrier systems. In chapter four, multifunctional and modular block co-polymers prepared from biocompatible monomers and linked by a bioreducible disulphide linkage have been prepared using a combination of ring-opening and atom-transfer radical polymerizations (ATRP). The presence of terminal functionality via ATRP allowed cell-targeting folic acid groups to be attached in a controllable manner, while the block co-polymer architecture enabled well-defined nanopartic1es to be prepared by a water-oil-water double emulsion procedure to encapsulate DNA with high efficiency. Gene delivery assays in a Calu-3 cell line indicated specific folatereceptor-mediated uptake of the nanoparticles, and triggered release of the DNA payload via cleavage of the disulfide link resulted in enhanced transgene expression compared to non-bioreducible analogues. These materials offer a promising and generic means to deliver a wide variety of therapeutic payloads to cells in a selective and tuneable way.
106

Controlled drug delivery by means of drug:ionic polysaccharide interactions

Morton-Holmes, Danya Frances January 1993 (has links)
The aim of the project was to investigate the potential of ionic polysaccharide/drug complexes as controlled release drug delivery systems. Two highly purified alginates from Laminaria hyperborea and Ascophyllum nodosum were characterised in terms of molecular weight, polydispersity and M:G ratio using gel permeation chromatography (GPC), low-speed sedimentation in the analytical ultracentrifuge and GPC combined with multi-angle laser light-scattering. Viscometric and nephelometric studies provided evidence that, above certain concentrations of propranolol, there was an interaction between propranolol and alginate in deionised water resulting in the formation of an insoluble complex, which dissociated in the presence of counter-ions, for example, sodium chloride. Binding studies were undertaken using equilibrium dialysis in order to quantify this interaction in the presence and absence of sodium chloride. These indicated that there was a one-to-one stoichiometric relationship between propranolol and the carboxyl group on each uronic acid reSidue of the alginate and that negative co-operativity was occurring, such that the binding of one propranolol molecule to the alginate made it more difficult for subsequent propranolol molecules to bind. The possible in-vacuo three-dimensional structure of the molecular complex was modelled using computational molecular modelling techniques. A freeze-dried complex of propranolol and alginate was prepared and characterised. In vitro investigations indicated that drug release from the complex (formulated as a suspension in deionised water or in isotonic glycerol solution) was delayed compared with release from a propranolol solution. The release of propranolol from the propranolol/ alginate complex was assessed in vivo using the anaesthetised rat as an animal model for nasal delivery. It was found that the rate of absorption of propranolol from the complex was much slower and was sustained over a greater period of time, compared with absorption from a propranolol solution. In addition, the bioavailability of the drug from the complex was comparable to that of the solution and to that of an intravenous dose carried out in rats by other workers (Hussain et al 1980b).
107

Visualization of the cellular uptake of nanoparticles

Adsley, Rosemary January 2013 (has links)
The effect of nanoparticle charge and conjugation to the cell penetrating peptide Tat on the uptake of nanoparticles into MRC-5 fibroblasts was investigated using a range of advanced imaging techniques including atomic force microscopy (AFM), scanning ion conductance microscopy (SICM) and fluorescence microscopy. New technologies are required to investigate the uptake of nanoparticles since although many studies have examined their destination within cells, little work has been done looking at the interaction between the nanoparticles and cell which also plays an important role. Polyacrylamide nanoparticles showed a clear correlation between increased positive charge and cellular uptake. These results obtained using fluorescence microscopy correlated well with those observed using AFM. Nanoparticles with low levels of positive charge caused minor effects on bilayer structure such as fusion of holes in the bilayer, whilst negatively charged nanoparticles had no effect on the bilayer. Polyacrylamide nanoparticles conjugated to the cell penetrating peptide Tat displayed greater cell uptake and increased effects on the bilayer depth and coverage than the similarly charged nanoparticles alone. This indicated that the peptide leads to enhanced uptake by additional mechanisms other than just the presence of a positive charge. In contrast, silica nanoparticles with high levels of positive and negative charge entered cells to a similar extent. However, when the interaction with the cell membrane was imaged using Scanning Surface Confocal Microscopy (SSCM), there were differences. Nanoparticles possessing a negative charge were often found to be associated with extensions of the membrane. Positively charged particles were also found associated with membrane extensions in some cases but were also observed isolated on the membrane. The results highlight the importance of using multiple imaging techniques to investigate cellular interaction and uptake in order to provide a complete picture of all the processes involved.
108

Economic analysis and randomised controlled trials : an investment appraisal approach

Backhouse, Martin E. January 2006 (has links)
Randomised controlled trials (RCTs) play a fundamental role in the development and marketing activities of pharmaceutical companies. They are the primary means of evaluating the tolerability, safety and efficacy of a drug, and for providing information relevant for pricing and reimbursement decisions and clinical decision-making. RCTs require a substantial investment by pharmaceutical companies and the financial consequences of poorly or sub-optimally designed trials are potentially substantial. Revenue does not materialise unless a licence to market a product is granted and sales may be restricted if a trial fails to provide evidence of sufficient strength or relevance for those involved in product adoption decisions. From a pharmaceutical company's perspective, the value of RCTs can therefore be judged on the contribution they make to the performance of a drug in the market and hence on their contribution to the performance of the firm. Consequently the design choices made in the planning of RCTs are effectively investment appraisal decisions. However, the application of investment appraisal techniques to RCT design has not previously been proposed. The purpose of this thesis is to consider how private sector investment appraisal methods might be applied to RCT design decision-making and to explore aspects of the practicalities of application. A general investment appraisal model is presented and its application to determine profit maximising RCT designs is illustrated. Considering the cost side of the investment appraisal equation, it is shown how decision-makers' requirements for cost-effectiveness evidence derived from trials could have a significant impact on the major determinants of cost (sample size and study duration) depending on their specific preferences for evidence defined over key components of RCT design. Considering the revenue side of the investment appraisal equation, it is shown how discrete choice analysis could be used to incorporate decision-makers' preferences for RCT designs into the planning of studies. Specifically, it is shown how the predicted probabilities derived from the application of this technique could be used within an investment appraisal framework. Directions for future research into the application of investment appraisal to RCT design are proposed.
109

An exploration of pharmacist-patient communication in clinic-style consultations

Greenhill, Nicola H. January 2010 (has links)
The importance of communication skills for pharmacists has been widely acknowledged. Research has shown that the use of good communication skills can improve patient health outcomes but little research has focussed on communication within new consultation based roles of pharmacists. This study aimed to explore the communication between pharmacists and patients in clinic style consultations and to investigate participant perceptions of communication and consultations. Eleven pharmacists were recruited to the study and were responsible for the recruitment of patients from their own practice; five pharmacists recruited a total of 18 patients. A semi-structured interview was conducted with each pharmacist and with each patient before and after their consultation. Consultations were audio-recorded and observed and all recordings were transcribed verbatim. Thematic analysis based on the principles of grounded theory was conducted. Consultations were additionally coded according to the Calgary–Cambridge guide. NHS Ethics and local research and development approvals were obtained. The data show that patient reports of communication skills during consultations can lack detail, indicating that actual consultation data is required in order to assess communication skills. Pharmacists reported a lack of communication skills training and stated that additional training would need to be focussed on specific, relevant skills and should involve underpinning theory combined with observation of practice and personalised feedback. Pharmacists observed in this study used of a variety of methods for structuring consultations including official computerised or paper based forms, rehearsed segments of speech, and mental checklists. Some difficulties in using computers in a way that did not interfere with communication were identified. Further training may help pharmacists to more effectively structure their consultations. The participants reported that location has important effects on the communication within consultations. Both pharmacists and patients valued privacy in enabling open and honest consultations, particularly in community pharmacy. While it was reported that infrequent use of consultation rooms can lead to stigma being associated with private consultations, the data suggest that having a dedicated space for pharmacist-patient consultations is important. Application of the Calgary-Cambridge guide to recorded consultations showed good usage of many of the skills by the study pharmacists but skills linked to creating a patient centred consultation were under-represented. Some data did not correspond to a specific skill within the guide. Analysis showed the key theme of social conversation, which is essential for relationship building, was present in the non-coded data. Building up a relationship was reported by both pharmacists and patients as important in facilitating communication and that trust in particular played an important part in achieving successful consultations. The study methods enabled collection of rich data about pharmacist-patient communication. The data show that many factors can influence communication within consultations including pharmacist training, location, relationships, structure and use of computers. Pharmacists may need to think widely when aiming to achieve effective consultations. The data suggest that pharmacists made good use of communication skills during consultations but could improve use of the skills that create patient-centred consultations. The Calgary-Cambridge guide could be used to focus both training and research in this area.
110

Critical processes in drug release from HPMC controlled release matrices

Pygall, Samuel R. January 2009 (has links)
This study has investigated the drug release mechanisms from hydroxypropyl methylcellulose (HPMC) hydrophilic matrices. A hypothesis was developed from interpretation of a previous study that drug surface activity has an influence on drug liberation. The validity of the hypothesis was tested by studying the interactions between HPMC and the two non-steroidal anti-inflammatory drugs diclofenac Na and meclofenamate Na, using tensiometry, rheology, NMR, neutron scattering and turbimetry. Meclofenamate Na was found to interact with HPMC, resulting in detectable changes in drug diffusion coefficients and polymer structure in solution. There were increases in HPMC solution solubility and changes in viscoelasticity, which suggested drug solubilisation of the methoxyl-rich regions of the polymer chains. Diclofenac Na did not show evidence of an interaction and exhibited changes consistent with a 'salting out' of the polymer. A confocal microscopy technique was used to image the drug effects on early gel layer development. The presence of drugs affected gel layer development, depending on the level of drug in the matrix and the concentration of sodium chloride in the hydration medium. Diclofenac Na matrices became increasingly susceptible to disintegration, while meclofenamate Na matrices exhibited resistance to the effects of sodium chloride. The influence of incorporated diluents on the gel layer was also investigated and it was found that lactose had a disruptive effect, whereas microcrystalline cellulose was relatively benign. When co-formulating drugs and diluents in the matrix, lactose acted to antagonise the effect of meclofenamate, but acted synergistically with diclofenac to reduce gel layer integrity and accelerate matrix disintegration. In contrast, MCC was found to have a relatively neutral effect on drug-mediated effects. HPMC particle swelling and coalescence are critical processes in gel layer formation extending drug release. Drug surface activity and capability of interacting with HPMC appears to influence particle swelling processes, affecting gel layer formation and provides a mechanistic explanation for the differing release profiles of diclofenac and meclofenamate Na.

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