The studies described in this thesis have investigated the complexities of automating Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS) systems, both in terms of sample introduction and data processing, and their subsequent testing and validation. Atmospheric pressure ionisation sources have revolutionised the use of mass spectrometry in the last 10 years. With the use of these robust and universal sources, large numbers of samples can now be processed in a single bioanalytical run. This has driven the need for high sample throughput automation. Described within are applications exploiting the versatility of the Gilson Automated Sample Processor using Extraction Columns (ASPEC) XLi Cartesian robot. In order to process the ever-increasing sample data, and to relieve this bottleneck in bioanalysis, in-house Interactive Chemical Information Software (ICIS-III<SUP>TM</SUP>) scripts were written and developed. The validation of the Finnigan MAT TSQ 700 mass spectrometer and its ancillaries, including the in-house written software, to Good Laboratory Practice (GLP) standards are described in detail. In addition, and as a further demonstration of the robustness and versatility of LC/MC/MC, the analysis of a compound extracted from dog lung homogenate following a novel solid phase extraction (SPE) method is recapitulated. A strategy for the method development of LC/MS/MS bioanalytical assays is likewise included.

The effects of a novel AMPA antagonist, LY293558, on reward and motor performance in rats, were compared with compounds known to be active in the mesolimbic dopamine reward system. Drugs were given systematically or directly into the core of the nucleus accumbens and reinforcing properties were assessed by two reward paradigms (brain stimulation and consumption of sucrose solutions). LY293558, administered by either route, significantly suppressed spontaneous locomotor activity in naive rats. Direct (but not systemic) antagonist injection significantly stimulated locomotion in habituated rats. As expected, when administered by either route, haloperidol blocked whereas MK-801 and amphetamine, stimulated locomotor activity. LY293558 had no significant effect on the rewarding properties of brain stimulation when injected by either route but produced a significant motor impairment. Systematic administrations of MK-801 and amphetamine facilitated whereas haloperidol inhibited reinforcement behaviour as measured by brain stimulation. Direct injections of these compounds into the core of the nucleus accumbens, had no significant effect on reward function, although haloperidol depressed rates of responding, an effect due to motor impairment. When given by either route, LY293558, MK-801 and haloperidol all suppressed consumption of sucrose solution in a two-bottle preference test. These decreases in consumption corresponded to doses that impaired motor function. In conclusion, LY293558 has effects on locomotor activity that depend on dose and route as well as previous experiences of the apparatus and the drug. Its effects on brain stimulation and consumption of sucrose solution are primarily mediated by motor effects, supporting the claimed link between the nucleus accumbens core and motor function.

In the present thesis, the Lewis strain, known to show a reduced corticosterone response to stressors relative to outbred Sprague-Dawleys, were more sensitive to the locomotor activating and stereotypy-inducing effects of d-amphetamine (0.75 - 3.0 mg/kg) than the Fischer strain, known to show an enhanced corticosterone response to stressors relative to outbred Sprague-Dawleys. The strains did not differ in their response to the acute locomotor activating effects of cocaine (10.0 - 40.0 mg/kg). Only Lewis rats showed place conditioning to d-amphetamine (0.25 - 1.0 mg/kg). In an initial drug sensitization (context-dependent) study, Lewis rats were more susceptible than Fischer rats to the sensitizing effects of cocaine. However, additional cocaine sensitization studies revealed a more complex array of findings. The appearance of cocaine-induced sensitization in either strain was found to be dependent upon a number of factors, including inter-injection interval (1 or 4 days), the environment where drug treatments were experienced, and drug dose. Importantly, both strains could display sensitization to cocaine. Fischer rats were more sensitive than Lewis rats to the acute locomotor activating and sensitizing effects of the D2/D3 agonist quinpirole, but, once again, the appearance of sensitization was dependent upon a number of factors (as described above for cocaine). The findings emphasise the complex behavioural effects of drugs acting on dopaminergic systems in the Fischer and Lewis strains of rat. They do not support the current, but contradictory, hypotheses that: a) the highly stress-responsive strain (Fischer) are consistently more susceptible to the behavioural activating (and reinforcing effects) of psychostimulants, and b) the so-called "addiction prone" strain (Lewis rats) are consistently more susceptible to the same effects.

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Hot melt extrusion (HME) is a preferred technique for preparing solid dispersions of poorly water soluble drugs, for the enhancement of drug dissolution rate and ultimately bioavailability. This technique is preferred to other methods due to the short time necessary for processing, and no need for solvents, which can be both problematic to patients and the environment. A wide variety of carriers is available, and may be selected based on factors such as the nature of release required and the compatibility with the drug. In this thesis, solid dispersions of two model BCS class 11 drugs, felodipine and celecoxib were prepared using Polyvinylpyrrolidone (PVP), EudragitSl L- IOO (LJOO) and Eudragit~ FS 30D (FS30D) by HME. The influence of molecular weight on the ability of the PVP to form a one phase amorphous dispersion and to stabilize the dispersed amorphous drug was investigated. Also, the feasibility of using the Eudragit polymers as both single and binary matrices for the generation of one-phase solid dispersions via ID1E, and to stabilize the amorphous drug during storage and dissolution was investigated. Pluronic Fl27 (FI27) was added to best performing binary and ternary systems to investigate the influence of surfactant on stability and dissolution. No difference was observed in the ability the different molecular PVP to form a one-phase molecular dispersion with felodipine or celecoxib and in stabilizing the amorphous form. The ability of methacrylate polymers to improve the pharmaceutical performance of the solid dispersions was dependent on drug loading. Also the performance of the binary methacrylate matrices depended on the ratio of the polymers. F127 improved the degree of supersaturation, and its effect on stabilization of the amorphous drug was concentrated dependent, with higher levels producing instability. The best performing formulation was the ternary system consisting of the higher ratio of FS30D with 10% F 127.

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