| 11. |
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| 12. |
- Henrohn, Dan, et al.
(författare)
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Acute haemodynamic response in relation to plasma vardenafil concentrations in patients with pulmonary hypertension
- 2012
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Ingår i: British Journal of Clinical Pharmacology. - : Wiley-Blackwell. - 0306-5251 .- 1365-2125. ; 74:6, s. 990-998
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Tidskriftsartikel (refereegranskat)abstract
- AIMS To evaluate the acute haemodynamic effects of a single oral dose of vardenafil and to study the drug concentration in relation to haemodynamic effects in patients with pulmonary hypertension (PH). METHODS Sixteen patients with PH (aged 29-85\ years), received one single oral dose of vardenafil (5, 10 or 20 mg). The haemodynamic effect was assessed over a 60 min period. Vardenafil plasma concentrations were measured after 15, 30, 45 and 60 min using liquid chromatography-tandem mass spectrometry. RESULTS At 60 min a reduction in mPAP with a median % decrease of -20.3% (range -48.3 to 3.0; P < 0.001) and an increase in cardiac output and the cardiac index with a median % change of 10.6% (range -25.0 to 88.1; P = 0.015) and 12.1% (range -24.0 to 94.4; P = 0.01) respectively was observed. The pulmonary vascular resistance (PVR) was reduced with a median % decrease of -28.9% (range -61.5 to -5.9; P < 0.001), and pulmonary selectivity was reflected by a median percent reduction of -16.9% (range -49.0 to 16.5; P = 0.002; n = 14) in the PVR/ systemic vascular resistance ratio. There was a correlation between the plasma concentrations of vardenafil and change in mPAP (r = -0.579, P = 0.019) and between vardenafil concentrations and change in PVR (r = -0.662, P = 0.005). CONCLUSIONS Vardenafil causes rapid changes in cardiopulmonary haemodynamics and there is a correlation between plasma vardenafil drug concentration and the acute changes in mPAP as well as PVR in patients with PH.
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| 13. |
- Krug, Oliver, et al.
(författare)
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Characterization of In Vitro Synthesized Equine Metabolites of the Selective Androgen Receptor Modulators S24 and S4
- 2012
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Ingår i: Journal of Equine Veterinary Science. - : Elsevier BV. - 0737-0806 .- 1542-7412. ; 32:9, s. 562-568
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Tidskriftsartikel (refereegranskat)abstract
- Several selective androgen receptor modulators (SARMs) have been synthesized and investigated in humans, rats, and dogs in the past, but no data are yet available concerning the metabolism of SARMs in horses. The aryl-propionamide-derived drug candidates S24 and S4 (andarine) have a strong androgen receptor binding affinity and show distinctive specific cell answers. Although no SARM drug candidate (aiming for testosterone replacement therapy) has completed clinical trials yet, S4 has been illicitly available via the Internet. These facts led to the prohibition of SARMs by the German equestrian federation, and the (mis)use of such compounds would further represent a doping rule violation in horse racing. In this study, the drug candidates S24 and S4 were subjected to in vitro metabolism experiments with equine liver microsomal preparations from a female Quarter Horse to obtain information about potential target analytes in equine doping control analysis. The enzymatically synthesized metabolites were characterized by liquid chromatography–tandem mass spectrometry and –high-resolution/high-accuracy mass spectrometry. All observed S24 and S4 equine metabolites are in agreement with earlier in vitro and in vivo studies in humans and dogs. Nevertheless, the relative percentage of generated equine metabolites (as determined from the analytes’ response in full-scan chromatography–tandem mass spectrometry and –high-resolution/high-accuracy mass spectrometry measurements) differs considerably from the reported profiles. Although the S24 metabolite pattern is comparably balanced concerning glucuronidated and sulfonated conjugates, the major S4 metabolite was found to be the unconjugated dephenylated compound, with a proportion of more than 90%.
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| 14. |
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| 15. |
- Lilienberg, Elsa, et al.
(författare)
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Investigation of Hepatobiliary Disposition of Doxorubicin Following Intrahepatic Delivery of Different Dosage Forms
- 2014
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 11:1, s. 131-144
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Tidskriftsartikel (refereegranskat)abstract
- Unresectable, intermediate stage hepatocellular carcinoma (HCC) is often treated palliatively in humans by doxorubicin (DOX). The drug is administered either as a drug-emulsified-in-Lipiodol (DLIP) or as drug loaded into drug eluting beads (DEB), and both formulations are administered intrahepatically. However, several aspects of their in vivo performance in the liver are still not well-understood. In this study, DLIP and DEB were investigated regarding the local and systemic pharmacokinetics (PK) of DOX and its primary metabolite doxorubicinol (DOXol). An advanced PK-multisampling site acute in vivo pig model was used for simultaneous sampling in the portal, hepatic, and femoral veins and the bile duct. The study had a randomized, parallel design with four treatment groups (TI–TIV). TI (n = 4) was used as control and received an intravenous (i.v.) infusion of DOX as a solution. TII and TIII were given a local injection in the hepatic artery with DLIP (n = 4) or DEB (n = 4), respectively. TIV (n = 2) received local injections of DLIP in the hepatic artery and bile duct simultaneously. All samples were analyzed for concentrations of DOX and DOXol with UPLC-MS/MS. Compared to DLIP, the systemic exposure for DOX with DEB was reduced (p < 0.05), in agreement with a slower in vivo release. The approximated intracellular bioavailability of DOX during 6 h appeared to be lower for DEB than DLIP. Following i.v. infusion (55 min), DOX had a liver extraction of 41 (28–53)%, and the fraction of the dose eliminated in bile of DOX and DOXol was 20 (15–22)% and 4.2 (3.2–5.2)%, respectively. The AUCbile/AUCVP for DOX and DOXol was 640 (580–660) and 5000 (3900–5400), respectively. In conclusion, DLIP might initially deliver a higher hepatocellular concentration of DOX than DEB as a consequence of its higher in vivo release rate. Thus, DLIP delivery results in higher intracellular peak concentrations that might correlate with better anticancer effects, but also higher systemic drug exposure and safety issues.
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| 16. |
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| 17. |
- Lundahl, Anna, et al.
(författare)
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High-resolution mass spectrometric investigation of the phase I and II metabolites of finasteride in pig plasma, urine and bile
- 2014
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Ingår i: Xenobiotica. - : Informa UK Limited. - 0049-8254 .- 1366-5928. ; 44:6, s. 498-510
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Tidskriftsartikel (refereegranskat)abstract
- 1. The metabolite profile of the 5 alpha-reductase type II inhibitor finasteride has been studied in pig plasma, urine and bile using high-resolution mass spectrometry. The porcine biotransformation products were compared to those formed by human liver microsomes and to literature data of recently identified human in vivo metabolites. The objective of this study was to gain further evidence for the validity of using pigs for advanced, invasive drug-drug interaction studies that are not possible to perform in humans. 2. The use of high-resolution mass spectrometry with accurate mass measurements enabled identification of the metabolites by calculation of their elemental compositions as well as their fragmentation patterns. 3. There was an excellent match between the porcine and human metabolic profiles, corroborating the pig as a model of human drug metabolism. The glucuronides of the two recently described human hydroxylated metabolites MX and MY and the carboxylated metabolite M3 were identified as the major biotransformation products of finasteride in pig urine and bile. 4. Furthermore, the CYP enzymes involved in the formation of the hydroxylated metabolites were characterized. Human recombinant CYP3A4 could produce the two major hydroxylated metabolites MX and MY, whereas human recombinant CYP2D6 formed MY only.
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| 18. |
- Lundahl, Anna, et al.
(författare)
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In Vivo Investigation in Pigs of Intestinal Absorption, Hepatobiliary Disposition, and Metabolism of the 5 alpha-Reductase Inhibitor Finasteride and the Effects of Coadministered Ketoconazole
- 2011
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Ingår i: Drug Metabolism And Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 39:5, s. 847-857
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Tidskriftsartikel (refereegranskat)abstract
- The overall aim of this detailed investigation of finasteride's pharmacokinetics (PK) and metabolism in pigs was to improve the understanding of the in vivo PK for this drug and its metabolites. Specific aims were to examine the effects of ketoconazole co-administration on the PK in three plasma compartments (the portal, hepatic and femoral veins), bile and urine and to utilize these data to in detail study the intestinal absorption, the liver extraction ratio and apply a semi-physiological based PK model to the data. The pigs received an intrajejunal dose of finasteride (0.8 mg/kg) either alone (n=5) or together with ketoconazole (10 mg/kg) (n=5), or an intravenous dose (0.2 mg/kg) (n=3). Plasma, bile and urine (collected from 0-6 hours) were analyzed with ultra performance liquid chromatography tandem mass spectrometry. Ketoconazole increased the bioavailability of finasteride from 0.36±0.23 to 0.91±0.1 (p<0.05) and the terminal half-life from 1.6±0.4 to 4.0±1.1 hours (p<0.05). From deconvolution it was found that the absorption rate from the intestine to the portal vein was rapid and the product of the fraction absorbed and the fraction that escaped gut wall metabolism was high (fa*FG≈1). Interestingly, the apparent absorption rate constant (k(a)) to the femoral vein was lower compared to the portal vein, probably because of binding and distribution within the liver. The liver extraction ratio was time-dependent and varied with the two routes of administration. After intrajejunal administration, from 1 6 hours the liver extraction ratio was significantly (p<0.05) reduced by the ketoconazole treatment from intermediate (0.41±0.21) to low (0.21±0.10).
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| 19. |
- Nilsson, Gunnel, 1950-
(författare)
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Zopiclone degradation in biological samples : Characteristics and consequences in forensic toxicology
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bio-analytical results are influenced by in vivo factors such as genetics, pharmacological and physiological conditions and in vitro factors such as specimen composition, sample additives and storage conditions. Zopiclone (ZOP) is a short-acting hypnotic drug (Imovane®) used for treatment of insomnia. ZOP is metabolized by three major pathways; oxidation to the active zopiclone N-oxide (ZOPNO), demethylation to the inactive N-desmethylzopiclone (NDZOP) and oxidative decarboxylation to other inactive metabolites. ZOP is increasingly being encountered in forensic cases and is a common finding in samples from drug-impaired drivers, users of illicit recreational drugs, victims of drug facilitated sexual assaults and forensic autopsy cases. ZOP is a notoriously unstable analyte in biological matrices and analytical results depend on pre-analytical factors, such as storage time and temperature. The overall aim of this thesis was to investigate the stability of ZOP and the factors of importance for degradation during storage in biological samples and to identify consequences for interpretation of results in forensic toxicology.In paper I, different stability tests in spiked samples were performed including short-term, longterm, freeze-thaw and processed stability. Analyses of ZOP were performed by gas chromatography with nitrogen phosphorous detection and ZOP concentrations were measured at selected time intervals. The degradation product 2-amino-5-chloropyridine (ACP) was identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The stability investigations showed a very poor short-term storage stability of ZOP.Therefore, in paper II, the influence of pre-analytical conditions was further investigated in dosed subjects. Whole blood from volunteers was obtained before and after oral administration of Imovane®. In this study, the influence from physiological factors such as drug interactions, matrix composition and plasma protein levels were minimized. The results showed that ZOP was stable in whole blood for only one day at room temperature, one week in a refrigerator and at least three months frozen in authentic as well as in spiked whole blood. The rapid degradation of ZOP at ambient temperature can cause an underestimation of the true concentration and consequently flaw the interpretation. However, by also analyzing the degradation product ACP the original concentration of ZOP may be estimated.In papers III and IV, two LC-MS-MS methods were validated for the quantitation of ACP, ZOP and NDZOP in blood and ACP, ZOP, NDZOP and ZOPNO in urine. These methods were used in a controlled pharmacokinetic study where whole blood and urine were obtained after oral administration of Imovane®. Samples of blood and urine were aliquoted, analyzed and stored under different conditions and the formation of ACP was monitored. Additionally, at each studied time point the pH of the blood and urine samples was measured using i-STAT® system. The results showed that ACP was formed in equimolar amounts to the degradation of ZOP and its metabolites.In urine samples, the formation of ACP occurred at elevated pH or temperature and mirrored the degradation of ZOP, NDZOP and ZOPNO. The high concentrations of metabolites, which also degraded to ACP, made it impossible to estimate the original ZOP concentration.The results from analysis of blood samples containing ACP were also used to develop mathematical models to estimate the original ZOP concentration. Both models showed strong correlation to the original ZOP concentration (r=0.960 and r=0.955) with p<0.01. This study showed that the equimolar degradation of ZOP and NDZOP to ACP could be used to estimate the original concentration of ZOP in blood samples.Absence of ACP in the blood or urine samples analysed strongly suggests that degradation has not occurred and that the measured concentration of ZOP is reliable. For proper interpretation in forensic cases, it is strongly recommended that ZOP and its metabolites as well as ACP are included in the analysis.
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| 20. |
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