Fenofibrate was chosen as the drug of interest in this study because of its poor water-solubility, highly unstable amorphous state and unpredictable crystallisation behaviour. The crystallisation behaviour of amorphous fenofibrate is essential information that primarily corresponds to the physical stability of solid dispersion formulations. This project aims to probe how to control the crystallisation of amorphous fenofibrate, enhance its aqueous solubility and improve its physical stability by using electrospun polymer blend matrices. A range of characterisation technologies including MTDSC, ATR-FTIR, PXRD, SCXRD, SEM, TEM, HS-PLM, nano-TA and ss-NMR were used to characterise the physicochemical properties of both the crystallisation process of fenofibrate, and fenofibrate solid dispersions. The amorphous fenofibrate was crystallised using heterogeneous nucleation techniques, including surface disruption and impurity addition (talc). The presence or absence of an open top surface (OTS) was found to be one of the key factors which dictated the crystallisation of the amorphous fenofibrate into specific polymorphs. The use of thermal treatment in addition to OTS was able to finely tune the selectivity of the crystallisation of fenofibrate to form I or/and form IIa. The use of a low percentage of talc as heterogeneous nuclei resulted in the crystallisation of the new fenofibrate polymorph III. The polymer blend fibres prepared by electrospinning were phase separated solid dispersions that improved the aqueous solubility of the fenofibrate in comparison to the fenofibrate crystals. The drug-polymer and polymer-polymer miscibility were found to be the key parameters that affected the physical stability of the incorporated amorphous drug and the phase separation in the formulations. Additionally, the in situ phase separation of the hydrophilic and hydrophobic polymers in the blends led to modified drug release. The drug release rate could be fine-tuned by altering the ratio of the polymers. The new knowledge generated by this work relates to the following areas: 1) an improved understanding of the crystallization process of fenofibrate and its polymorphic control; 2) the use of polymer blend matrices in electrospun fibres that leads to the stabilization of amorphous drugs when they are incorporated in those fibres; and 3) the modification of the drug release profiles via the use of hydrophilic and hydrophobic polymer blend matrices for electrospinning.

Dopamine is involved with many aspects of normal brain function, such as movement, emotion and motivation and its dysregulation is associated with diseases, such as schizophrenia and Parkinson's disease. Drug treatments for these conditions may cause side effects, hence, it is important to understand their mechanisms. Amphetamine administration is a popular model for studying reward, schizophrenia and behaviour. I modified this model to investigate changes in functional dopaminergic activity in the whole rat brain using Pharmacological magnetic resonance imaging (PhMRI). Halothane proved to be suitable anaesthetic for these experiments because it did not affect stimulated dopamine release unlike a-choralose. Acute amphetamine challenge caused widespread increases in blood-oxygenation-level-dependent (BOLD) signal intensity in many subcortical dopaminergic structures, with a rim of negative BOLD observed in the cortex. Amphetamine acts by blocking reuptake of dopamine leading to activation of all dopamine receptor subtypes. To tease apart the mechanisms of the amphetamine response, I pretreated rats with specific antagonists prior to amphetamine. This had contrasting effects on the BOLD signal. D1 antagonist blocked most of the positive BOLD response to amphetamine whereas the D2 antagonist predominantly blocked and negative BOLD response. The acute effects of selective D1 and D2 agonists and antagonists on the BOLD response were observed in subcortical dopaminergic structures, largely corresponding with stimulation or blockade of the specific receptors types. My experiments show that the recently-developed phMRI technique can be used to dissect the mechanisms of drug action in the whole brain.

No description available.

Methods for the determination of the hydroxylation of biphenyl in rat liver and the glucuronidation of 4-methylumbelliferone in rat and rabbit liver preparations have been developed by the modification of existing methods. Using these methods, the activities of biphenyl-hydroxylase and 4-methylumbelliferone glucuronyl transferase and p-nitrobenzoic acid nitroreductase and cytochrome P450 have been determined in normal and pregnant rats. When expressed per gram of liver,biphenyl-4-hydroxylase, 4-methylumbelliferone glucuronyl transferase and cytochrome P450 were found to be decreased in the livers of 19-20 day, but not 15-16 day, pregnant rats. However, liver weight also increased so that the total liver content of these parameters was similar to that of non-pregnant animals; total microsomal protein and nitroreductase activity were increased. Pregnancy did not prevent the induction of these parameters with pheno-barbitone. None of these parameters is altered in the full-term pregnant rabbit, although the hydroxylation of coumarin is decreased. The action of hexobarbitone in full-term pregnant rats is prolonged, confirming the in vitro studies. The effects of pregnancy on hepatic microsomal enzymes could not be reproduced by pretreatment with progesterone or oestradiol, alone or combined, though both of these endogenous steroids, and also oral contraceptive steroids, inhibited the hydroxylation and nitroreduction in vitro. Pretreatment with high doses of chlormadinone, norgestrel, norethynodrel, ethynodiol or mestranol for eighteen days, did not alter any of the liver parameters, though a single dose of norethynodrel caused inhibition of biphenyl-4-hydroxylation at one and twenty-four hours after dosing. Eighteen days treatment with ethynodiol and mestranol combined, increased the hydroxylation. long-term oral administration of a low dose of chlormadinone or ethynodiol, but not norethynodrel, decreased the hydroxylation but none of the other parameters. Pretreatment of rats with oral contraceptive steroids, except chlormadinone, decreased the duration of action of hexobarbitone in vivo. A method for the determination of the urinary metabolites of phenacetin by gas chromatography has been developed by modification of previous methods. The pattern of excretion in pregnant and non-pregnant rats is similar. Humans on the "pill" possibly excrete more unchanged phenacetin and less conjugated N-acetyl-p-aminophenol than controls.

Urgent action is required to combat the ongoing threat of antimicrobial resistance. Trojan horse conjugates, where antimicrobials are linked to a nutrient carrier, can evade permeability-related resistance through active transport of drugs into bacterial cells. The work presented herein explores modification of the linker moiety between a citrate siderophore and ciprofloxacin, as well as the addition of glycosyl groups to catecholate siderophore moieties to mimic the salmochelins; stealth siderophores which can evade the mammalian defence protein siderocalin. Two linkers were investigated, one containing a carbamate and the other a disulfide bond neighbouring a carbamate group. These were chosen to give intracellular release of the antimicrobial, either by the action of carboxylesterases or through reduction of the disulfide bond by thiolate anions in the cytoplasm, respectively. A carbamate-linked conjugate was synthesised and screened against wild type E. coli, and demonstrated lower antimicrobial activity than that for the parent drug. Screening against a bacterial strain lacking the outer membrane ferric citrate receptor FecA demonstrated that FecA is not essential for uptake of the synthesised conjugate. The synthesis of a disulfide linked conjugate was unsuccessful, due to release of free ciprofloxacin during the final deprotection step. A salmochelin-inspired conjugate was synthesised. Whilst it demonstrated reduced antimicrobial activity against wild type E. coli in iron rich media, compared to the parent drug, higher antimicrobial activity was observed in iron-limited media, suggesting active uptake. A DNA gyrase assay showed that the inhibitory activity of this conjugate was lower than the free drug, suggesting that the antimicrobial activity observed under iron deficiency may be due extracellular iron sequestration by the siderophore.

Nanoparticles are difficult to define specifically hut usually encompass engineered particles ranging in size from 1 to 1000 nm. The physical and chemical properties. of nanoparticles can vary significantly from those of their bulk counterparts largely due to their large surface area to volume ratios. Approximately 40% antimicrobial agents emerging from development programs exhibit low solubility. This results in inadequate bioavailability, pharmacokinetics and stability. The use of appropriate nano-carriers has been shown to improve the efficacy of antimicrobial agents with the' explanation that the biodistribution of the antimicrobial follows that of the carrier rather than being dependent on the physiochemical properties of the compound itself. Therefore characteristics such as solubility and bioavailability can be enhanced. Here, a range of poorly water-soluble antifungal agents, biocides and an antibiotic were processed using a novel emulsion-evaporation technique to produce organic nanoparticles. These preparations were characterised on the basis of size and zeta potential and tested for inhibitory activity against relevant microorganisms including: C. albicans, E. coli, S. aureus and MRSA. Nanoparticle formulated antimicrobials were usually more inhibitory than the equivalent eo-solvent dissolved antimicrobials or water dissolved salt equivalents where available. However, efficacy was dependent on nanoparticle composition. Optimisation of nanoparticle dichlorophen inhibitory activity was attempted using a generic polymer and surfactant screen. The results were subsequently utilised in a computer modelling design approach. Due to formulation problems, predictive optimisation was not possible. However, nanoparticles of dichlorophen were usually most inhibitory when increased loading ratios of sodium dodecyl sulphate and hydroxy propyl methyl cellulose and reduced loading ratios of dichlorophen and gelatin were used in the preparation. No correlations between particle size, zeta potential and inhibitory activity were identified. No correlation between the inhibitory activities of blank nanoparticles and active equivalents were identified. A detailed series of controls prepared for one formulation usually produced low MIC values. However, the nanoparticle formulation exhibited the greatest efficacy. This suggested that enhanced activity due to nanoparticle formulation of the antimicrobial was not simply attributed to a synergistic effect between the different materials. The molecular response of S. aureus SH1000 to nanoparticle-formulated ciprofloxacin was investigated using RNA-Seq. All 5 investigated treatments induced differential gene expression. Moreover, comparative analysis between nanoparticle formulated and DMSO dissolved ciprofloxacin treated S. aureus SH1000 revealed the differential expression of 61 transcripts. No significant differential expression in DNA repair and replication targets was observed. This suggested that ciprofloxacin may not be more bioavailable to S. aureus SH1000 and therefore enhanced efficacy is not attributed to increased bioavailability. However, genes involved in stress response and cell division were shown to be up regulated in response to nanoparticle delivery. The results also revealed that 39 transcripts were differentially expressed due to nanoparticle exposure alone and these included stress response, cell division and virulence-associated genes. The identified differentially expressed transcripts are unlikely to account for the enhanced efficacy associated with nanoparticle delivery. Nanoparticles represent a novel approach to the delivery of hydrophobic anti microbials in aqueous dispersions. The advantageous features of nanoparticles are discussed throughout this thesis. The study used a variety of approaches with the aim of elucidating the mechanisms underpinning the observed enhancement in antimicrobial activity. The improved efficacy observed could not be correlated with any physical characteristics of the particles used. The transcriptional profiling results suggested that the improved antimicrobial activity observed was not associated with differential molecular targeting, and challenges current concepts that link enhanced efficacy with increased bioavailability.

Aim: This study’s aim was to improve our understanding of the dietary behaviours of people receiving opioid substitution treatment (OST) in the UK. Setting: The study focuses on people receiving prescribing interventions for OST from pharmacies in Oxfordshire, England. Methods: Dietary behaviours were assessed using a longitudinal convergent parallel mixed methods research design. Quantitative methods included a socio-demographic and drug use questionnaire, SF-36 health related quality of life questionnaire, 24-hour dietary recall interview, and anthropometry measures. Qualitative semi-structured face-to-face interviews were conducted to understand how individuals’ experiences with food and diet influence their dietary behaviours. Follow-ups were conducted four months after baseline data collection. The same quantitative and qualitative research tools were applied at the second stage of the study. Results: Mean (SD) Body Mass Index for males (n=15) and females (n=10) exceeded the normal range [25.2 (5.9) kg/m2 and 33.3 (8.6) kg/m2, respectively] at baseline. Males decreased to the normal range at follow-up [mean (SD) = 24.1 (± 6.2) kg/m2]. Females increased to Obesity Class II at follow-up [mean (SD) = 35.1 (± 8.0) kg/m2]. Non-starch polysaccharide intakes were significantly lower than the Reference Nutrient Intake (RNI). Iron intakes among females were significantly below the RNI. Saturated fat intake and sodium intake exceeded the RNI. Eleven (44%) participants had multiple health conditions. Food consumption was influenced by factors such as childhood eating, mental health issues, digestive issues, limited financial resources, drug use and accommodation. Conclusions: People receiving OST in the UK may be at risk of development of non-communicable diseases (NCDs). Dietary and nutritional recommendations may benefit this population. Recommendations must accommodate for specialised needs. Further research is required in the UK to understand aspects such as multi-morbidity rates, rates of overweight and obesity, food acquisition, food preparation skills and food expenditures.

The aim of the study was to determine the attitudes of patients towards neuroleptic medication in relation to compliance, in order to develop a measure that will allow clinicians to predict likely compliance difficulties. A catchment area sample of 106 adult schizophrenics completed three new self-report measures, a rating scale of attitudes to medication (Drug Attitudes Scale - DAS), a scale based on the theory of planned behaviour (Theory of Planned Behaviour Scale - TPB) and a measure of compliance with medication (Drug Behaviour Scale - DBS). Keyworkers rated compliance, using an established measure (the Kemp Scale). Three reliable variables from these scales were renamed positive, negative and conditional positive attitude and together named the Drug Compliance and Attitude Scale (DCAS). The DCAS predicted both keyworker (Kemp) and self-report (DBS) measures of compliance. The DCAS had modest concurrent validity and was superior in predictive power to the most popular established scale. The non-compliance reported by patients was found to be mostly because they changed the time they took the medication rather than because of changing dosage and involved increasing as well as reducing frequency. Reasons for deviation from prescription included active manipulation of subjective state as well as passive non-compliance. It has been shown that compliance with neuroleptic regimes is a complex set of behaviours which involves more than simply taking or not taking medication. Future research on enhancing compliance among this patient group will need to consider the complex nature of both attitudes to medication and behavioural responses. Clinical implications of the study include the use of the DCAS to enhance compliance, to identify those patients for whom the medication may not be effective and to evaluate treatments combining drug and psychological interventions.

Although opioids have been used for centuries in the management of pain, the opioid receptor family has only recently been cloned, thus allowing detailed studies on opioid receptor mediated signal transduction pathways to be performed. In addition, two novel opioid peptides, endomorphin-1 and -2, were identified in 1997, and it is believed that these represent new endogenous u-opioid receptor ligands. This thesis represents a study into opioid receptor mediated increases in Ca2+ j and provides an investigation into the cellular signaling pathways of endomorphin-1 and -2. Activation of the recombinant 6-opioid receptor expressed in CHO cells (CH05) by D- Pen2'5 -enkephalin produced a concentration dependent, pertussis toxin and thapsigargin sensitive increase in Ca2+ i in whole cell suspensions. Truncation of this receptor by the 37 C-terminal amino acids produced a rightward shift in the concentration response curve for Ca j release. In single adherent CHOu, CHOk (CHO cells expressing recombinant u- or K-opioid receptors respectively) or CH05 cells, application of fentanyl, spiradoline or D-Pen2' -enkephalin respectively produced an increase in Ca i in some cells. The putative u.-opioid receptor endogenous ligands endomorphin- 1 and endomorphin-2 bound with high affinity and selectivity to u-opioid receptors from CHOu, and SH-SY5Y cells. Endomorphin-1 and -2 concentration-dependently inhibited forskolin stimulated cAMP formation in CHOp. and SH-SY5Y cells and endomorphin-1 and -2 produced an increase in Ca2+ j in CHOji cells. Prolonged endomorphin-1 pretreatment desensitized the -opioid receptor in CHO cells, characterized by a reduction in maximal endomorphin-1 mediated cAMP inhibition, an up-regulation of cAMP formation and was due to receptor - G protein uncoupling. Endomorphin-1 pre-treatment produced a rapid loss of cell surface receptors from CHOp. cells, which was possibly accompanied by receptor degradation. Collectively these data add to our understanding of opioid receptor-mediated signal transduction pathways.

1. The molecular basis of selectivity and gating were investigated in wild-type and mutant forms of the inward rectifier K+ channel Kir2.1 (IRK1). 2. Kir2.1 channels show characteristic time-dependent gating kinetics due to a reversible voltage-dependent channel block by cytoplasmic polyamines. Mutations at Asp 172 in the M2 domain revealed that a negative charge at this position is the main criterion of time-dependent gating kinetics in Kir2.1. 3. Kir channels are blocked by Cs+ and Rb+ in a voltage-dependent manner, characteristic of many Kir channels. Rb+ and Cs+ block in Kir2.1 was abolished by replacing Asp 172 by Asn, but was re-established by a change to Gln, narrowing the pore. However, blocking affinity was reduced by the mutation to Gln. 4. When Asp 172 was mutated to Glu, narrowing the pore but retaining the negative charge, block by both Cs+ and Rb+ was increased relative to wild-type. 5. Replacing Gly 168 in M2 by Ala was suggested to widen the pore at position 172. The effect of this mutation on Cs+ and Rb+ block was relatively small. 6. There appears to be a balance between charge and pore size in determining whether icons block or permeate. A major part of the selectivity of Kir2.1 is associated with Asp 172 in the M2 domain. This site also determines the time-dependent activation gating of the channel. 7. Mutation of Asp 172 to Ser were predicted to abolish both Cs+ and Rb+ block in Kir2.1, but blocking affinity was similar to WT. Therefore, other properties of the pore must contribute to Cs+ and Rb+ block at position 172 in addition to the electrostatic and steric effects identified in this study.