Kublbeck J.,University of Eastern Finland |
Laitinen T.,University of Eastern Finland |
Jyrkkarinne J.,University of Eastern Finland |
Rousu T.,Novamass Ltd |
And 10 more authors.
Biochemical Pharmacology | Year: 2011
The so-called human xenosensors, constitutive androstane receptor (hCAR), pregnane X receptor (hPXR) and aryl hydrocarbon receptor (hAhR), participate in drug metabolism and transport as well as in several endogenous processes by regulating the expression of their target genes. While the ligand specificities for hPXR and hAhR are relatively well described, this property of hCAR still remains fairly unclear. Identifying hCAR agonists for drug development and for studying hCAR biology are hindered mainly by the unique properties of the receptor, such as the high constitutive activity and complex signaling network but also by the lack of robust and reliable assays and cellular models. Here, validated reporter assays for these three xenosensors are presented and thereafter used to screen a large set of chemicals in order to find novel selective hCAR ligands. We introduce a novel selective hCAR agonist, FL81, which can be used as a stable positive control in hCAR activity assays. Our established receptor-selective ligand identification methods consisting of supporting biological assays and molecular modeling techniques are then used to study FL81 as well as other discovered ligands, such as diethylstilbestrol, o,p′-DDT, methoxychlor and permethrin, for their ability to specifically activate hCAR and to regulate the CYP enzyme expression and function. © 2011 Elsevier Inc. Source
Rousu T.,University of Oulu |
Tolonen A.,Admescope Ltd.
Bioanalysis | Year: 2012
Background: The use of high-resolution MS systems for quantitative bioanalysis is a growing field, even though a clear majority of bioanalytical methods are still based on MS/MS with triple quadrupole (QqQ) instrumentation. The recent advances in TOF-MS technology have provided increased linear range and a high selectivity of detection by increased mass resolution and mass accuracy, making these instruments attractive for quantitative analysis due to lack of a need for compound-specific detection reaction optimization and their capability to collect data for a high number of compounds by sensitive wide mass range data acquisition. Materials & Methods: Here, 11 steroids spiked to human plasma were analyzed by LC-MS using both a QqQ MS system and a TOF instrument operating at 12,000 mass resolution. Sample preparation was performed by hybrid SPE technology. Results: The LOD were 0.5-5 and 0.5-20 ng/ml in plasma for all analytes with QqQ and TOF-MS detection, respectively. Conclusion: Although the results show wider linear range and slightly better sensitivity for most of the compounds with QqQ in comparison to TOF, acceptable performance was obtained for most of the compounds within the range of LOD to 2000 ng/ml (in plasma), this was also the case with LC-TOF-MS analysis. The main problem in TOF-MS analysis at 12,000 mass resolution from plasma was selectivity rather than sensitivity or linear range. © 2012 Future Science Ltd. Source
Tolonen A.,Admescope Ltd. |
Pelkonen O.,University of Oulu
Toxicology | Year: 2015
For quantitative in vitro-. in vivo extrapolation (QIVIVE) of metabolism for the purposes of toxicokinetics prediction, a precise and robust analytical technique for identifying and measuring a chemical and its metabolites is an absolute prerequisite. Currently, high-resolution mass spectrometry (HR-MS) is a tool of choice for a majority of organic relatively lipophilic molecules, linked with a LC separation tool and simultaneous UV-detection. However, additional techniques such as gas chromatography, radiometric measurements and NMR, are required to cover the whole spectrum of chemical structures. To accumulate enough reliable and robust data for the validation of QIVIVE, there are some partially opposing needs: Detailed delineation of the in vitro test system to produce a reliable toxicokinetic measure for a studied chemical, and a throughput capacity of the in vitro set-up and the analytical tool as high as possible. We discuss current analytical challenges for the identification and quantification of chemicals and their metabolites, both stable and reactive, focusing especially on LC-MS techniques, but simultaneously attempting to pinpoint factors associated with sample preparation, testing conditions and strengths and weaknesses of a particular technique available for a particular task. © 2013 Elsevier Ireland Ltd. Source
Valitalo P.,University of Eastern Finland |
Kuusisto M.,University of Eastern Finland |
Ranta V.P.,University of Eastern Finland |
Raatikainen K.,Kuopio University Hospital |
Hautajarvi H.,Admescope Ltd.
British Journal of Anaesthesia | Year: 2014
BackgroundDespite being increasingly used for pain management, only two studies, with controversial results, have evaluated the epidural use of oxycodone.MethodsTwenty-four women, aged 26-64 yr, undergoing elective gynaecological surgery were enrolled in this randomized, double-blinded, parallel group study. The subjects were administered either i.v. oxycodone and epidural placebo (IV group; n=12) or epidural oxycodone and i.v. placebo (EPI group; n=12) after operation. Oxycodone was administered as a single dose of 0.1 mg kg-1. An epidural catheter for drug administration was placed at T12/L1 and a spinal catheter for cerebrospinal fluid (CSF) sampling at L3/4. Plasma and CSF were frequently collected for the analysis of oxycodone and its major metabolites. The primary outcomes were the peak concentration (C max), time to peak concentration (Tmax), and the exposure (AUClast) of oxycodone in CSF and plasma. The secondary outcome was the analgesic efficacy, measured as the total dose of rescue fentanyl during the first four postoperative hours.ResultsIn the EPI group, the median oxycodone Cmax and AUClast in the CSF were 320-and 120-fold higher, respectively, compared with the IV group. The total dose of rescue fentanyl was significantly lower in the EPI group (seven subjects needed 16 doses) than in the IV group [12 subjects needed 71 doses (P=0.001)]. No serious or unexpected adverse events were reported.ConclusionsEpidural oxycodone provides much higher CSF concentrations and possibly better analgesic efficacy than does i.v. oxycodone.Clinical trial registrationEudraCT reference number: 2011-000125-76. © 2014 The Author . Source
Lehtinen T.,Clinical Research Services Turku |
Tolonen A.,Admescope Ltd. |
Turpeinen M.,University of Oulu |
Uusitalo J.,Technopolis Plc |
And 4 more authors.
Biopharmaceutics and Drug Disposition | Year: 2013
Purpose: The objectives were to determine the cytochrome P450 (CYP) enzymes involved in the metabolism of ospemifene and its main hydroxylated metabolites and to examine the effects of CYP inhibitors and inducers on ospemifene pharmacokinetics. Methods: In vitro metabolism studies were conducted using human liver microsomes; CYP-selective inhibitors and CYP-specific substrates were used to determine the roles of nine CYP isoforms in ospemifene metabolism. Two Phase 1 clinical trials were conducted in healthy postmenopausal women; crossover designs examined the effects of pretreatment with the CYP modulators rifampicin, ketoconazole, fluconazole and omeprazole on ospemifene pharmacokinetics. Results: Although several CYP inhibitors decreased the in vitro formation of ospemifene metabolites, none of them completely blocked metabolism. Roles for CYP3A4, CYP2C9, CYP2C19 and CYP2B6 in the metabolism of ospemifene and its two main metabolites, 4-hydroxyospemifene and 4′-hydroxyospemifene, were confirmed. The in vivo experiments demonstrated that ospemifene serum concentrations were decreased by rifampicin pretreatment, increased by ketoconazole or fluconazole pretreatment, and minimally affected by omeprazole pretreatment. Conclusions: The clinical pharmacokinetic findings and in vitro data suggest that CYP3A4 is important for ospemifene metabolism, but other CYP isoforms and metabolic pathways also contribute. Strong CYP3A or CYP2C9 inducers (e.g. rifampicin) would be expected to decrease the exposure to ospemifene. Ospemifene should be used with caution when coadministered with the modest CYP3A inhibitor ketoconazole and should not be coadministered with the potent CYP3A/CYP2C9/CYP2C19 inhibitor fluconazole. The potent CYP2C19 inhibitor omeprazole is unlikely to cause clinically significant changes in ospemifene pharmacokinetics. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd. Source