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Evaluation of the chromatographic separation in metabolomics studies has primarily been done using preselected sets of standards or by counting the number of detected features. An alternative approach is to calculate each feature's co-feature ratio, which is a combined selectivity measurement for the separation (i.e. extent of co-elution) and the MS-signal (i.e. adduct formation and in-source fragmentation). The aim of this study was to demonstrate how the selectivity of different HILIC stationary phases can be evaluated using the co-feature ratio approach. The study was based on three sample types; plasma, urine and cell extracts. Samples were analyzed on an UHPLC-ESI-Q-ToF system using an amide, a bare silica and a sulfobetaine stationary phase. For each feature, a co-feature ratio was calculated and used for multivariate analysis of the selectivity differences between the three stationary phases. Unsupervised PCA models indicated that the co-feature ratios were highly dependent on type of stationary phase. For several metabolites a 15-30 fold difference in the co-feature ratio were observed between the stationary phases. Observed selectivity differences related primarily to the retention patterns of unwanted matrix components such as inorganic salts (detected as salt clusters), glycerophospholipids, and polyethylene glycols. These matrix components affected the signal intensity of co-eluting metabolites by interfering with the ionization efficiency and/or their adduct formation. Furthermore, the retention pattern of these matrix components had huge influence on the number of detected features. The co-feature ratio approach has successfully been applied for evaluation of the selectivity performance of three HILIC stationary phases. The co-feature ratio could therefore be used in metabolomics for developing selective methods fit for their purpose, thereby avoiding generic analytical approaches, which are often biased, as type and amount of interfering matrix components are metabolome dependent.

Selective androgen receptor modulators (SARMs) are a class of androgen receptor drugs, which have a high potential to be performance enhancers in human and animal sports. Arylpropionamides are one of the major SARM classes and get rapidly metabolized significantly complicating simple detection of misconduct in blood or urine sample analysis. Specific drug-derived metabolites are required as references due to a short half-life of the parent compound but are generally lacking. The difficulty in metabolism studies is the determination of the correct regio and stereoselectivity during metabolic conversion processes. In this study, we have elucidated and verified the chemical structure of two major equine arylpropionamide-based SARM metabolites using a combination of chemical synthesis and liquid chromatography- mass spectrometry (LC-MS) analysis. These synthesized SARM-derived metabolites can readily be utilized as reference standards for routine mass spectrometry-based doping control analysis of at least three commonly used performance-enhancing drugs to unambigously identify misconduct.

Awareness of the potential problems caused by drug compounds in the environment has increased over the last decade, both among researchers and with the public. This thesis describes the development of analytical methods and their application to wetlands constructed for purification of wastewater from e.g. drug compounds. Different wetlands were investigated using microcosm-models, to determine their biodegradation. An enantioselective and sensitive SFC/ESI-QqQ method was developed and validated for the enantiomeric separation of atenolol, metoprolol, propranolol and metoprolol acid. It was applied measuring the enantiomeric fraction of the compounds in three different microcosm-models. The same microcosms were also used to investigate the transformation products formed in these wetlands. In this work, LC/ESI-QToF was used to identify the transformation products using standard references, the original compounds or analogs, comparing their accurate mass and product ions. One not previously observed major transformation product identified from propranolol were 1-naphthol. Several minor transformation products were also identified, showing how diverse the formation might be in wetlands.

A second part compares the matrix effect of ESI/MS using SFC and reversed phase LC, utilizing general screening methods for drug compounds in plasma, horse urine and influent/effluent wastewater. These matrices are known to suffer from matrix effects when using the ESI-source, and if SFC would suffer less than LC it could be a great benefit. The matrix profiles showed that this is likely not the case: although SFC was affected by different interferences then LC. One example is the formation of clusters causing major ion suppression. This unique SFC-phenomenon was investigated further, showing that metal ions were separated and eluted at different retention times, forming clusters in the ion source between metal ions and the organic modifier and/or make-up solvent.

In conclusion, the first part of this thesis describes analytical methods for determination of drug compounds in the environment, using LC and SFC, connected to both high and low resolving MS. The second part focuses on fundamental analytical chemistry, comparing the matrix effects of SFC/ESI-MS with LC/ESI-MS, and investigates the cluster phenomena observed for samples containing alkali ions and an organic modifier in the mobile phase in SFC/ESI-MS.

Doping control in equine sports is important for a fair competition, but also to ensure the integrity of the betting system, as well as for animal welfare reasons. To detect the use of illicit compounds, screening for the parent compound is common. However, by using a metabolite as the analytical target instead, the detection time can be prolonged. For some compounds, the use of a metabolite is a necessity since the parent drug may not be detected at all.

The metabolites of the selective androgen receptor modulators (SARM) S1, S4 and S22 were investigated in horse urine and plasma. The unchanged parent compounds had the longest detection time in plasma, but were not detected at all in urine. Instead, the longest detection time was measured for the metabolites 2-amino-5-nitro-4-(trifluoromethyl)phenyl hydrogen sulfate (SARMs S1 and S4) and 2-amino-5-cyano-4-(trifluoromethyl)phenyl hydrogen sulfate (SARM S22). These metabolites were thus suggested as analytical targets for doping control in urine while the parent compounds were suggested for plasma samples. 2-amino-5-nitro-4-(trifluoromethyl)phenyl hydrogen sulfate could also be produced in large quantities by the fungus Cunninghamella elegans to potentially be used as reference compound.

The horse metabolites of the SARM LGD-4033 were also studied in urine and plasma. The formate adduct of LGD-4033 had the longest detection time in plasma and in urine after hydrolysis with β-glucuronidase. In non-hydrolyzed urine, the glucuronidated LGD-4033 was detected instead.

Different in vitro models were used to predict in vivo metabolites of roxadustat, a hypoxia-inducible factor stabilizer. Cunninghamella elegans was successful in producing more metabolites compared to human and equine liver microsomes and human hepatocytes.

The metabolite detection and identification in all experiments were accomplished using a UHPLC-Q-TOF MS instrument, where the high-resolution MS data was vital in determining which metabolites were formed.

The thesis shows the benefits of investigating the metabolites of doping substances to allow for a successful doping control method in horse urine and plasma by prolonging the detection time. It also highlights the usefulness of Cunninghamella elegans as an alternative to the more commonly used in vitro models for both predicting and producing metabolites.

LGD-4033 has been found in human doping control samples and has the potential for illicit use in racehorses as well. It belongs to the pharmacological class of selective androgen receptor modulators (SARMs) and can stimulate muscle growth, much like anabolic steroids. However, SARMs have shown superior side effect profiles compared to anabolic steroids, which arguably makes them attractive for use by individuals seeking an unfair advantage over their competitors. The purpose of this study was to investigate the metabolites formed from LGD-4033 in the horse in order to find suitable analytical targets for doping controls. LGD-4033 was administered to three horses after which plasma and urine samples were collected and analyzed for metabolites using ultra high performance liquid chromatography coupled to a high resolution mass spectrometer. In horse urine, eight metabolites, both phase I and phase II, were observed most of which had not been described in other metabolic systems. Six of these were also detected in plasma. The parent compound was detected in plasma, but not in non-hydrolyzed urine. The longest detection times were observed for unchanged LGD-4033 in plasma and in urine hydrolyzed with β-glucuronidase and is thus suggested as the analytical target for doping control in the horse. The metabolite profile determined in the horse samples was also compared to those of human urine and fungal incubate from Cunninghamella elegans. The main human metabolite, dihydroxylated LGD-4033, was detected in the horse samples and was also produced by the fungus. However, it was a not a major metabolite for horse and fungus, which highlights the importance of performing metabolism studies in the species of interest.

BACKGROUND: The nitrate-nitrite-nitric oxide (NO) pathway may represent a potential therapeutic target in patients with pulmonary arterial hypertension (PAH). We explored the effects of dietary nitrate supplementation, with the use of nitrate-rich beetroot juice (BRJ), in patients with PAH.

METHODS AND RESULTS: We prospectively studied 15 patients with PAH in an exploratory randomized, double-blind, placebo-controlled, crossover trial. The patients received nitrate-rich beetroot juice (∼16 mmol nitrate per day) and placebo in 2 treatment periods of 7 days each. The assessments included; exhaled NO and NO flow-independent parameters (alveolar NO and bronchial NO flux), plasma and salivary nitrate and nitrite, biomarkers and metabolites of the NO-system, N-terminal pro-B-type natriuretic peptide, echocardiography, ergospirometry, diffusing capacity of the lung for carbon monoxide, and the 6-minute walk test. Compared with placebo ingestion of BRJ resulted in increases in; fractional exhaled NO at all flow-rates, alveolar NO concentrations and bronchial NO flux, and plasma and salivary levels of nitrate and nitrite. Plasma ornithine levels decreased and indices of relative arginine availability increased after BRJ compared to placebo. A decrease in breathing frequency was observed during ergospirometry after BRJ. A tendency for an improvement in right ventricular function was observed after ingestion of BRJ. In addition a tendency for an increase in the peak power output to peak oxygen consumption ratio (W peak/VO₂ peak) was observed, which became significant in patients reaching an increase of plasma nitrite >30% (responders).

CONCLUSIONS: BRJ administered for 1 week increases pulmonary NO production and the relative arginine bioavailability in patients with PAH, compared with placebo. An increase in the W peak/VO₂ peak ratio was observed after BRJ ingestion in plasma nitrite responders. These findings indicate that supplementation with inorganic nitrate increase NO synthase-independent NO production from the nitrate-nitrite-NO pathway.

Objective: Endothelial function, including the nitric oxide (NO)-pathway, has previously been extensively investigated in heart failure (HF). In contrast, studies are lacking on the NO pathway after heart transplantation (HT). We therefore investigated substances in the NO pathway prior to and after HT in relation to hemodynamic parameters.

Design: 12 patients (median age 50.0 yrs, 2 females), heart transplanted between June 2012 and February 2014, evaluated at our hemodynamic lab, at rest, prior to HT, as well as four weeks and six months after HT were included. All patients had normal left ventricular function post-operatively and none had post-operative pulmonary hypertension or acute cellular rejection requiring therapy at the evaluations. Plasma concentrations of ADMA, SDMA, L-Arginine, L-Ornithine and L-Citrulline were analyzed at each evaluation.

Results: In comparison to controls, the plasma L-Arginine concentration was low and ADMA high in HF patients, resulting in low L-Arginine/ADMA-ratio pre-HT. Already four weeks after HT L-Arginine was normalized whereas ADMA remained high. Consequently the L-Arginine/ADMA-ratio improved, but did not normalize. The biomarkers remained unchanged at the six-month evaluation and the L-Arginine/ADMA-ratio correlated inversely to pulmonary vascular resistance (PVR) six months post-HT.

Conclusions: Plasma L-Arginine concentrations normalize after HT. However, as ADMA is unchanged, the L-Arginine/ADMA-ratio remained low and correlated inversely to PVR. Together these findings suggest that (i) the L-Arginine/ADMA-ratio may be an indicator of pulmonary vascular tone after HT, and that (ii) NO-dependent endothelial function is partly restored after HT. Considering the good postoperative outcome, the biomarker levels may be considered “normal” after HT.

Canagliflozin (CFZ) is a sodium-glucose cotransporter-2 inhibitor that has shown promising results as a drug for the treatment of insulin dysregulation in horses. Even though CFZ is used clinically, no pharmacokinetic data has previously been published. In this study, the pharmacokinetics of CFZ after administration of a single oral dose of 1.8 mg/kg in eight healthy Icelandic horses was examined. Additionally, the effect of treatment on glucose and insulin levels in response to a graded glucose infusion was investigated. Plasma samples for CFZ quantification were taken at 0, 0.33, 0.66, 1, 1.33, 1.66, 2, 2.33, 2.66, 3, 3.5, 4, 5, 6, 8, 12, 24, 32, and 48 h post administration. CFZ was quantified using UHPLC coupled to tandem quadrupole mass spectrometry (UHPLC-MS/MS). A non-compartmental analysis revealed key pharmacokinetic parameters, including a median T_max of 7 h, a C_max of 2350 ng/mL, and a t_1/2Z of 28.5 h. CFZ treatment reduced glucose (AUC_GLU, p = 0.001) and insulin (AUC_INS, p = 0.04) response to a graded glucose infusion administered 5 h after treatment. This indicates a rapid onset of action following a single dose in healthy Icelandic horses. No obvious adverse effects related to the treatment were observed.

A simple and robust capillary zone electrophoresis method was developed and validated for the determination of amoxicillin and clavulanate, ampicillin, phenoxymethyl penicillin (Pen V) as well as flucloxacillin. Capacitively coupled contactless conductivity detection was employed as detection mode that makes CE a simple and economic tool for money-constrained laboratories. The developed method is straightforward and user-friendly. It offers good sensitivity and sufficient selectivity for the routine assay of the selected penicillins. The repeatabilities were <1.9% RSD for relative peak areas and <1% RSD for migration times for all the analytes. The method showed good linearity (R²  > 0.995) within the 80-120% range of the target concentration (0.5 mg/mL) for each antibiotic. The accuracy of the method, evaluated by standard fortification at three levels, was good for all the analytes. An extended robustness study was performed by varying ±10% of the optimum value of TRIS concentration, l-histidine concentration and temperature in a full factorial design at two levels. This was to evaluate larger than usual variability of factors on the assay value, in order to better cover potential global variance in lab conditions and equipment. Finally, the method was applied for the determination of percent (%) content of all antibiotics in available formulations.

This review describes briefly the high rate of counterfeiting of antimicrobial drugs with focus upon its immediate health consequences. The major part of this review encompasses accounts of the improvements achieved in the domain of miniaturization of capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-(CD)-D-4). The application of this principle into the development of portable devices as well as its application to counter the health-system-crippling phenomenon of counterfeit antibiotic formulations, are discussed in the context of developing countries.