Cystic fibrosis (CF) is the most common autosomal recessive disorder affecting Caucasian populations. The pathophysiology of this disorder predisposes the lungs of affected patients to chronic infection, typically by Pseudomonas aeruginosa, which is the main cause of morbidity and mortality. Recently, attention has focused on aerosolised polymyxins, which are given prophylactically in an effort to limit infection and subsequent lung damage. This class of antimicrobial compounds is highly active against P. aeruginosa and possess the advantage that resistance rarely develops. However, the rapid lung clearance of antibiotics is a well documented phenomenon and it was postulated that polymyxin treatment could be further improved by liposomal encapsulation. As part of the development of liposomal polymyxin B, analytical methodology (radiolabelling, HPLC and protein assay) applicable to liposomal formulations was established. Liposomes were prepared by the dehydration-rehydration method and encapsulation efficiencies were determined for a number of phospholipid compositions. Vesicles were characterised with respect to size, zeta potential, morphology and release characteristics. The surface hydrophobicity of vesicles was quantified by hydrophobic interaction chromatography and it was found that this method produced comparable results to techniques conventionally used to assess this property. In vivo testing of liposomal polymyxins demonstrated that encapsulation successfully prevented the rapid pulmonary clearance of PXB. Antimicrobial activity of liposomal formulations was quantified and found to be dependent on both the vesicle surface characteristics and their release profile. Investigation of the interaction of PXB with lipopolysaccharide was undertaken and results demonstrated that PXB caused significant structural distortion of the lipid A region. This may be sufficient to abrogate the potentiating action of LPS in the inflammatory cascade.

The underlying theme of this study is to enhance the permeation of a antimicrobial agent in the skin by employing chemical (enhancers and supersaturated systems) or physical (iontophoresis) techniques. The hydrochloride salt of chlorhexidine (CHX), a poorly soluble salt, was used throughout this study. The effect of ionisation on in vitro permeation rate across the excised human epidermis was investigated using Franz-type diffusion cells. Saturated solutions of CHX were used as donor and the variable studied was vehicle pH. Permeation rate was increased with increasing vehicle pH. The pH effect was not related to the level of ionisation of the drug. The effect of donor vehicle was also studied using saturated solutions of CHX in 10% and 20% ethanol as the donor solutions. Permeation of CHX was enhanced by increasing the concentration of ethanol which could be due to the higher concentration of CHX in the donor phase and the effect of ethanol itself on the membrane. The interplay between drug diffusion and enhancer pretreatment of the epidermis was studied. Pretreatment of the membrane with 10% Azone /PG demonstrated the highest diffusion rate followed by 10% oleic acid/PG pretreatment compared to other pretreatment regimens (ethanol, dimethyl sulfoxide (DMSO), propylene glycol (PG), sodium dodecyl sulphate (SDS) and dodecyl trimethyl ammonium bromide (DTAB). The potential of supersaturated solutions in enhancing percutaneous absorption of CHX was investigated. Various anti-nucleating polymers were screened in order to establish the most effective agent. Polyvinylpyrrolidone (PVP, K30) was found to be a better candidate than its lower molecular weight counterpart (K25) and hyroxypropyl methylcellulose (HPMC). The permeation studies showed an increase in diffusion rate by increasing the degree of saturation.

The initial objective of this work was to evaluate and introduce fabrication techniques based on W/O/W double emulsion and O/W single emulsion systems with solvent evaporation for the incorporation of a surrogate macromolecule (BSA) into microspheres and microcapsules fabricated using P(HB-HV), PEA and their blends. Biodegradation, expressed as changes in the gross and ultrastructural morphology of BSA loaded microparticulates with time was monitored using SEM concomitant with BSA release. Spherical microparticulates were successfully fabricated using both the W/O/W and O/W emulsion systems. Both microspheres and microcapsules released BSA over a period of 24 to 26 days. BSA release from P(HB0HB)20% PCL 11 microcapsules increased steadily with time, while BSA release from all other microparticulates was characterised by an initial lag phase followed by exponential release lasting 6-11 days. Microcapsules were found to biodegrade more rapidly than microspheres fabricated from the same polymer. The incubation of microparticulates in newborn calf serum, synthetic gastric juice and pancreatin solution showed that microspheres and microcapsules were susceptible to enzymatic biodegradation. The in vitro incubation of microparticulates in Hank's buffer demonstrated limited biodegradation of microspheres and microcapsules by simple hydrolysis. BSA release was thought to occur as a result of the macromolecule diffusing through either inherent micropores or via pores and channels generated in situ by previously dissolved BSA. However, in all cases, irrespective of percentage loading or fabrication polymer, low encapsulation efficiencies were obtained with W/O/W and O/W techniques (4.20.9%-15.50.5%, n=3), thus restricting the use of these techniques for the generation of microparticulate sustained drug delivery devices. (DX 187, 341).

No description available.

In recent years it has been shown conclusively that at least two cannabinoid receptors, termed CB1 and CB2, exist in mammalian tissues. Previous studies using the mouse isolated vas deferens have yielded results which suggest that this tissue contains cannabinoid CB1 receptors which, when activated, can mediate inhibition of electrically-evoked contractions. However, there is evidence which indicates that several of the cannabinoid receptor agonists investigated in this study may exert their effects via non-CB, or even non- cannabinoid mechanisms. In the present study, this evidence was further investigated using the cannabinoid-mediated inhibition of electrically-evoked contractions in the mouse isolated vas deferens as a model of study. The results obtained from studies using the cannabinoid receptor antagonists O-1184 and the CB1-selective SR141716A highlighted the existence of a level of agonist-dependent antagonism in mouse isolated vas deferens. This was indicated by discrepancies obtained in the pKB values of these antagonists against the compounds under investigation. In this series of investigations it was observed that the endogenous cannabinoid receptor agonist, anandamide and the capsaicin-anandamide hybrid compound, arvanil were less potently antagonised by the CB1selective antagonist/inverse agonist, SR141716A than the highly CB1-selective agonist methanandamide. Such discrepancies in pKB values indicate that anandamide and arvanil may be acting on a receptor type distinct from the cannabinoid CB1 receptor. Additionally this series of studies indicated that anandamide and WIN55212-2 were more potently antagonised when non-cumulative responses to these compounds were constructed, indicating the possibility of tolerance developing to these compounds during the construction of cumulative concentration response curves. Several, more recent studies have indicated that anandamide and its metabolically more stable analogue methanandamide may exert their actions in part through vanilloid VR1 receptors. Upon further investigation using the vanilloid VR1 receptor antagonist capsazepine in addition to SR141716A, it was observed that the effects of anandamide, methanandamide, and the capsaicin-anandamide hybrid arvanil could be attenuated by both antagonists. These results indicate that these three agonists can act through both receptor types to mediate their effects in the mouse isolated vas deferens. In this study the putative water-soluble cannabinoid receptor agonist, O-1057 was shown to inhibit the of electrically-evoked contractions in the mouse isolated vas deferens when only water was used as a vehicle. This effect was inhibited by the cannabinoid receptor antagonists O-1184 and SR141716A, providing evidence that this novel water-soluble compound was acting through the CB1 receptor. In a further study the ability of the endogenous compound palmitoylethanolamide and a range of cannabinoids which can act on the CB2 in addition to the CB1 receptor, to downregulate mast cell degranulation was investigated. It was observed that PEA, CP55940 and WIN55212-2 but not the highly CB2 receptor-selective L759656 could exert this effect. It was not possible to investigate the effects of the CB2 receptor antagonist/inverse agonist SR144528 at this time.

No description available.

This study had explored the top ten countries medicines expenditure and it was found that United Kingdom had the highest drop in spending by 2015. Preliminary investigations conducted found the reasons for this drop, focusing cost-containment initiatives on medicines expenditure practice. Further preliminary investigations also made to identify the region and participants, where and who the study should be conducted. These investigations used secondary analysis of data. Realistic evaluation framework used in this study to uncover the factors involved in the practice of cost-containment initiatives on medicines expenditure and their impact on the hospitals. The factors involved identified by what works, in what conditions, why and which outcomes. Elite interviewing conducted on chief pharmacists to identify these factors. From this study, cost-containment initiatives found to be complex with inter-related factors that could affect the savings made. In many respects, the organisations practised similar interventions nationally, regionally and locally. However, variations found in terms of setting priorities of cost-containment initiatives and measurement of cost-effectiveness. This study identified the decision-making process of chief pharmacists were mainly pragmatic that included local rationality in terms of politics in choosing which cost-containment initiative was to be prioritised and implemented. Various facilitators and barriers also found to affect the outcomes of the cost-containment initiatives. This study also acknowledged that chief pharmacists faced many pressures such as adhering to local and national polices to contribute towards cost-savings. As a result, this study had developed a model for cost-containment initiatives of medicines expenditure. The model summarised the context-mechanism-outcome configurations of the factors involved in the practice of cost-containment initiatives on medicines expenditure in the hospitals and their impact from the chief pharmacists’ point of view. It could become a feasible guideline for pharmacists in conducting, standardising the evaluation and implementation of cost-containment initiative. It would be useful as easy reference for future research.

No description available.

In this thesis, studies of the kinetic and mechanism of racemisation of several drug-like molecule have been presented. Chapter 1 provides background information on the general mechanisms of racemisation of drugs in general, and hydantoin derivatives. In particular including reviews of the hydrolysis and the mechanism of base-catalysed racemisation of hydantoin derivatives. The synthesis of different chiral hydantoins, thiohydantoins, thiazolidine-diones, and rhodanines is presented in Chapter 2. Several enantio-enriched 5-substituted 1-acetyl-2-thiohydantoins and two tri-substituted 2-thiohydantoins have been synthesised. Further racemic thiohydantoin derivatives including mono, di, and tri-substituted 2-thiohydantoins have also been prepared. Chapter 3 focuses on the kinetics and mechanism of hydrolysis of 5-substituted 1-acetyl-2-thiohydantoins in physiological-like buffers. The key reaction involves de-acetylation and this is followed by the hydrolysis of the resulting 5-substituted 2-thiohydantoins. Sodium hydroxide and hydrochloric acid have also been used for the hydrolysis of 1-acetyl-5-phenyl-2-thiohydantoin. Similarly, the hydrolysis of several 5-substituted 2-thiohydantoins has been studied. The rate constants for hydrolysis suggest that the 5-substituted 1-acetyl-2-thiohydantoins hydrolyses faster than the subsequent hydrolysis of 5-substituted 2-thiohydantoins. Chapter 4 focuses on the racemisation of 5-substituted 1-acetyl-2-thiohydantoins and shows that substituents at N-1 decelerate racemisation. Racemisation of tri-substituted 2-thiohydantoins is fast in comparison with 5-substituted 1-acetyl-2-thiohydantoins. The substituents at the asymmetric carbon affect the rate of racemisation. The solvent kinetic isotope effect on the racemisation were determined for different substituted 2-thiohydantoins and supported the SE1 mechanism of racemisation. Chapter 5 concerns further confirmation of the mechanism of racemisation by comparing kdeu and krac and this confirms the SE1 mechanism for racemisation of 5-substituted 1-acetyl-2-thiohydantoin as kdeu/krac for all compounds approaches 1. For the racemic 5-substituted 2-thiohydantoins the rate constants of deuteration have been obtained using 1H-NMR spectroscopy and showed fast replacement of hydrogen by deuteron. Assuming kdeu = krac, we can order the rate constants for racemisation form high to low as rhodanine > thiohydantoin > thiazolidine-2,4-dione > hydantoin.

Chronic pain {CP} is a major health problem that affects about 20% of adults worldwide. Unlike acute, physiological pain, which resolves promptly once the painful stimulus is removed, CP can last for months, years or even a lifetime. CP, which includes inflammatory pain {IP} that is associated with both tissue injury and the accompanying inflammation and peripheral neuropathic pain {NP} that is a direct consequence of a lesion or disease affecting the peripheral nervous system {PNS}, often is a constant burden, degrades peoples’ quality of life, and costs billions of pounds. Patients with CP usually complain of either: a) continuous or intermittent spontaneous, un-provoked pain; or b) hypersensitivity, due to either increased pain from a stimulus that normally provokes pain or pain due to a stimulus that does not normally provoke pain. Successful therapy for CP, particularly NP, remains a challenge because the currently available drugs are largely ineffective and many result in adverse side effects. Therefore, there is a pressing need to understand the pathophysiology of CP, in order to devise appropriate palliative and curative strategies. CP is believed to be due, at least partly, to increased excitability of normally quiescent dorsal root ganglion {DRG} neurons, which convey sensory information from the periphery to the central nervous system {CNS}. However, the underlying ionic and molecular mechanisms of this neuronal hyperexcitability and spontaneous activity {SA} are poorly understood. The aim of this research project was to examine the hypothesis that during peripheral CP states, hyperexcitability in DRG neurons could be due to increased expression of hyperpolarisation-activated cyclic nucleotide-gated {HCN} channels, possibly in combination with a change in their activation properties. This is because these channels, which are composed of 4 subunits {HCN1-4}, produce an excitatory inward current, termed the hyperpolarisation-activated {Ih} current in neurons, that depolarizes the membrane potential toward the threshold of action potential {AP} generation. To test this hypothesis, several integrated approaches, including behavioural pharmacology, in vivo electrophysiology, and immunofluorescent staining, were used in two rat models of CP that were compared to appropriate controls. The rat models of CP were: a) chronic inflammatory pain {CIP} model, which involved induction of hindlimb inflammation with complete Freund’s adjuvant {CFA}; and b) chronic neuropathic pain {CNP} model that involved L5 spinal nerve {SN} axotomy, in addition to loose ligation of the L4 SN with neuro-inflammation inducing chromic gut, referred to as modified SN Axotomy {mSNA}. The objectives of the current project were to: (i) evaluate, using behavioural pharmacology, the influence of modulating the HCN channels with the Ih-specific blocker, ZD7288, on pain hypersensitivity in both CIP and CNP. (ii) determine, using in vivo intracellular voltage and current recordings, the difference in AP parameters between normal and mSNA-treated L4 DRG neurons and the effect of ZD7288 on SA in the mSNA-treated L4 DRG neurons. (iii) determine, using immunofluoresence, the types of DRG neuron that express HCN1-HCN3 subunits in normal rats and whether expression of these subunits is altered in both CIP and CNP. The results showed: 1. In both CIP and CNP, peripheral administration of ZD7288 resulted in significant attenuation of mechanical hypersensitivity and a non-significant absence of spontaneous pain {SP}. 2. In the L4 DRG neurons of mSNA-treated animals with CNP, ZD7288 had no effect on the frequency of SA from low-threshold mechanoreceptors {LTM} and induced changes in hyperpolarisation-associated AP parameters in Aα/β-fibre DRG neurons. 3. In both CIP and CNP, an increased proportion of small and medium sized DRG neurons express HCN2, but not HCN1 or HCN3, channel protein. Taken together, the findings suggest that HCN channels, particularly HCN2, in specific sub-populations of DRG neurons contribute to the development!of CIP and CNP.