liu.seSearch for publications in DiVA
Change search
Refine search result
1 - 26 of 26
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Bengtsson, Finn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology .
    Therapeutic drug monitoring of psychotropic drugs - TDM "Nouveau"2004In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 26, no 2, p. 145-151Article in journal (Refereed)
    Abstract [en]

    TDM applied in psychiatry dates back several decades. The reason for this is that, after the advent of modem clinical psychopharmacology around the middle of the past century, an insight came to common knowledge about the existence of (1) a large inter-individual pharmacokinetic (PK) variability for virtually all psychoactive drugs and (2) a worse clinical efficacy not only in inadequate drug concentrations but also in excessively high concentrations. From this concept, the definition of a therapeutic concentration "window" was evidenced for a substantial number of, primarily, antidepressant drugs. However, with the further extensive development of the clinically available pharmacopoeia of psychoactive drugs from the later 1980s until today, the concept of less toxic compounds than before has commonly been launched in the marketing strategies for these newer drugs. This concept also led to the idea that TDM was no longer necessary for the newer types of psychoactive drugs, a position backed up by difficulties in unraveling concentration-effect relationships generally for these drugs in clinical trials. The present survey summarizes the background history for TDM in psychiatry and makes a critical appraisal of why a "lack" of definition of concentration-effect relationships for newer psychoactive drugs is now common. This survey also provides the reader with a novel concept challenging ambient TDM strategies (referred to as TDM "traditionelle") in psychiatry by forwarding a theoretical model called TDM "nouveau." In this model both inter- and intraindividual (over time) PK variation is suggested to be used for dose optimization by TDM in a naturalistic clinical setting. The previous concept of a simple, common concentration "window" existing for all such drugs is questioned by promotion of the use of available PK data merely as "guiding principles" rather than as "reference values" when interpreting the TDM outcome in individual cases.

  • 2.
    Dolores Cherma Yeste, Maria
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Reis, Margareta
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Hägg, Staffan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Ahlner, Johan
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Bengtsson, Finn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Therapeutic Drug Monitoring of Ziprasidone in a Clinical Treatment Setting2008In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 30, no 6, p. 682-688Article in journal (Refereed)
    Abstract [en]

    There is limited information on the pharmacokinetics of ziprasidone (ZIP) in naturalistic clinical settings. The objective of this study was to investigate the concentrations of ZIP and its active metabolite S-methyl-dihydroziprasidone (SMDZ), and the dose-normalized concentrations, using routine therapeutic drug monitoring (TDM) data. A high-performance liquid chromatographic method for determining serum concentrations of these substances for routine clinical use was established at the TDM Laboratory in Linkoping, Sweden. This analytical service was available to all physicians in Sweden. Between January 2001 and December 2004, 545 analyses, representing samples from 370 patients, were performed. The median daily ZIP dose was 120 mg (range 20-320 mg). In all, 121 steady-state trough specimens with essential clinical information were included in the pharmacokinetic evaluation. The median (25th to 75th percentile) serum concentration of ZIP was 125 nmol/L (82-188 nmol/L). The SMDZ:ZIP ratio decreased with increasing serum concentration of ZIP. The median (25th to 75th percentile) dose-normalized concentrations (nmol L-1 mg(-1) d(-1)) for ZIP and SMDZ were 1.13 (0.74-1.77) and 0.62 (0.45-0.86), respectively, with SMDZ:ZIP ratio of 0.57 (0.42-0.79). The overall coefficients of variation for close-normalized scruin concentrations of ZIP, SMDZ, and SMDZ:ZIP ratio were 62%, 56%, and 57%, respectively (n = 121). Smoking women had lower normalized ZIP concentrations than nonsmoking women. Twenty-eight patients with repeated eligible TDM analyses were studied for intraindividual variance over time. In summary, great interindividual and intraindividual differences in ZIP concentrations were observed. TDM of ZIP maybe used for individual dose adjustments and monitoring medication adherence.

  • 3.
    Haglund, Sofie
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology. Linköping University, Faculty of Health Sciences.
    Vikingsson, Svante
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Söderman, Jan
    Division of Medical Diagnostics, Laboratory Medicine, Ryhov Hospital, Jönköping;.
    Hindorf, Ulf
    Department of Gastroenterology, Lund University Hospital, Lund.
    Grännö, Christer
    Department of Medicine, Ryhov Hospital, Jönköping.
    Danelius, Margareta
    Department of Internal Medicine, Ersta Hospital, Stockholm, Sweden.
    Coulthard, Sally
    Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne, United Kingdom.
    Peterson, Curt
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology.
    Almer, Sven
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Endocrinology and Gastroenterology UHL.
    The Role of Inosine-5'-Monophosphate Dehydrogenase in Thiopurine Metabolism in Patients With Inflammatory Bowel Disease2011In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 33, no 2, p. 200-208Article in journal (Refereed)
    Abstract [en]

    BACKGROUND:: There is a large interindividual variability in thiopurine metabolism. High concentrations of methylthioinosine-5'-monophosphate (meTIMP) and low concentrations of 6-thioguanine nucleotides (6-TGNs) have been associated with a lower response rate and an increased risk of adverse events. In this study, the role of inosine-5'-monophosphate dehydrogenase (IMPDH) for differences in metabolite patterns of thiopurines was investigated.

    METHODS:: IMPDH activity and thiopurine metabolite concentrations were determined in patients with inflammatory bowel disease and a normal thiopurine methyltransferase (TPMT) phenotype and meTIMP/6-TGN concentration ratio > 20 (n = 26), in patients with a metabolite ratio ≤20 (n = 21), in a subgroup with a metabolite ratio <4 (n = 6), and in 10 patients with reduced TPMT activity. In vitro studies were conducted on human embryonic kidney cells (HEK293) with genetically engineered IMPDH and TPMT activities.

    RESULTS:: Patients with metabolite ratios >20 had lower IMPDH activity than those with ratios ≤20 (P < 0.001). Metabolic ratios >20 were only observed in patients with normal TPMT activity. Downregulation of IMPDH activity in HEK293 cells was associated with an increase in the concentration of meTIMP (fold change: 17 up to 93, P < 0.001) but, unexpectedly, also of 6-thioguanosine monophosphate (fold change: 2.6 up to 5.0, P < 0.001).

    CONCLUSIONS:: These data question the general view of IMPDH as the rate-limiting enzyme in the phosphorylation of thiopurines. Investigations of other mechanisms are needed to more fully explain the various metabolite patterns and outcomes in patients under treatment.

  • 4.
    Hindorf, U.
    et al.
    Division of Gastroenterology, Department of Internal Medicine, University Hospital, Lund, Sweden, Division of Gastroenterology, Department of Internal Medicine, University Hospital, SE-221 85 Lund, Sweden.
    Peterson, Curt
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Oncology UHL.
    Almer, Sven
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology . Östergötlands Läns Landsting, Centre for Medicine, Department of Endocrinology and Gastroenterology UHL.
    Assessment of thiopurine methyltransferase and metabolite formation during thiopurine therapy: Results from a large swedish patient population2004In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 26, no 6, p. 673-678Article in journal (Refereed)
    Abstract [en]

    This study examined thiopurine methyltransferase (TPMT) and the relationship to thioguanine nucleotides (TGN) and methylthioinosine monophosphate (meTIMP) in a large Swedish patient population. The current hypothesis is that the cytotoxic effects of thiopurine drugs are mediated by the incorporation of TGN into DNA. The authors assayed the TPMT activity in red blood cells from 1151 subjects and the concentrations of TGN (n = 602) and meTIMP (n = 593) from patients treated with thiopurine drugs. The TPMT frequency distribution in both adults and children showed some differences from what had been found in unselected general populations. Children had lower median TPMT activity than adults (12.0 versus 12.9 U/mL RBC, P < 0.001). Relative differences in both TGN formation [medians: normal TPMT, 1.3, intermediate TPMT, 3.3, low TPMT, 47.9 pmol/8 × 108 RBC per mg azathioprine (AZA), P < 0.001] and meTIMP formation (medians: normal TPMT, 13, intermediate TPMT, 7.3, low TPMT, 0 pmol/8 × 108 RBC per mg AZA, P = 0.001) per 1 mg administered drug were noted among the 3 TPMT activity groups. Women formed higher concentrations of both TGN (1.5 versus 1.3 pmol/8 × 108 RBC per mg AZA, P = 0.01) and meTIMP (14.4 versus 10.7 pmol/8 × 108 RBC per mg AZA, P = 0.01) than men did. There was a significant correlation between the AZA dose and the meTIMP concentrations (r = 0.45, P < 0.001). Furthermore, dose alterations made in subjects with normal TPMT (n = 84) and intermediate TPMT (n = 22) activity resulted in more pronounced increases in TGN concentrations (170 versus 30 pmol/8 × 10 8 RBC, P < 0.001) in intermediate TPMT activity, whereas in normal TPMT activity changes in meTIMP concentrations were more pronounced (1.3 versus 0 nmol/8 × 108 RBC, P < 0.001). In normal TPMT activity both metabolites increased in a dose-dependent fashion, whereas in intermediate TPMT activity only TGN concentrations increased. The results of this study demonstrate the dynamic nature of thiopurine metabolism and its importance for thiopurine dosing.

  • 5. Hindorf, U
    et al.
    Peterson, Curt
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Almer, Sven
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Molecular and Clinical Medicine, Gastroenterology and Hepatology. Östergötlands Läns Landsting, Centre for Medicine, Department of Endocrinology and Gastroenterology UHL.
    Assessment of Thiopurine Methyltransferase and Metabolite Formation During Thiopurine Therapy: Results from a Large Swedish Patient Population2004In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 26, p. 673-678Article in journal (Refereed)
  • 6.
    Jones, A Wayne
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of clinical chemistry.
    Holmgren, A
    Kugelberg, Fredrik
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Concentrations of scheduled prescription drugs in blood of impaired drivers: Considerations for interpreting the results2007In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 29, no 2, p. 248-260Article in journal (Refereed)
    Abstract [en]

    We report the concentrations of scheduled prescription drugs in blood samples from people arrested in Sweden for driving under the influence of drugs (DUID). The investigation covered a 2 year period 2004 (N = 7052 cases) and 2005 (N = 7759 cases) and was prompted by recent legislation stipulating zero-concentration limits in blood for controlled substances. However, prescription drugs are exempt from the zero-limit law provided that the medication was being used in accordance with a doctor's prescription. The blood concentrations of various psychoactive substances were compared with the limits of quantitation of the analytic method used and the so-called therapeutic concentration range according to various reference books and tabulations. Diazepam [N = 1950 (26%)] and nordazepam [N = 2168 (28%)] were the therapeutic agents most frequently identified in these forensic blood samples along with other benzodiazepines such as alprazolam [N = 430 (5.6%)], flunitrazepam [N = 308 (4.0%)], and nitrazepam [N = 222 (2.9%)]. The newer hypnotics, exemplified by zolpidem [N = 148 (1.9%)] and zopiclone [N = 111 (1.5%)], were also high on the list of psychoactive substances identified. Interpreting the concentration of a prescription drug in blood in relation to whether the person had taken an overdose or was abusing the substance in question is not always easy. The age, gender, degree of obesity, and ethnicity of the person concerned, the pharmacokinetic profile of the drug, polymorphism of drug-metabolizing enzymes as well as liver and kidney function and blood hematocrit need to be considered. Among preanalytic factors, stability of the drug in blood after sampling, the type of tubes and preservatives used, the dosage form and route of administration deserve consideration. When therapeutic drug monitoring concentrations are compared with forensic toxicology results, then the plasma-to-whole blood distribution ratio of the drug also needs to be considered. In blood samples from DUID suspects, the concentrations of many commonly used sedatives and hypnotics exceeded the accepted therapeutic limits, which gives an indication of the abuse potential of these types of medications. © 2007 Lippincott Williams & Wilkins, Inc.

  • 7.
    Jones, A Wayne
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of clinical chemistry.
    Larsson, H
    Distribution of diazepam and nordiazepam between plasma and whole blood and the influence of hematocrit2004In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 26, no 4, p. 380-385Article in journal (Refereed)
    Abstract [en]

    The binding of drugs to plasma proteins is important to consider when concentrations in whole blood (eg, in forensic toxicology) are compared with therapeutic and toxic concentrations based on the analysis of plasma or serum. The plasma to whole blood distribution of diazepam (D) and its major metabolite nordiazepam (ND) was investigated under in vitro and ex vivo conditions. Studies in vitro were done by spiking whole blood with D and ND to give concentrations ranging from 0.1 to 1.0 μg/g. Venous blood was also obtained from hospital blood donors (n = 66) after informed consent. The hematocrit, hemoglobin, and water content of blood specimens were determined by routine procedures before D and ND were added to produce target concentrations of ∼0.5 μg/g for each substance. The ex vivo work was done with blood specimens from hospital outpatients who were being medicated with D. Concentrations of D and ND were determined in body fluids by capillary column gas chromatography after adding prazepam as internal standard and solvent extraction with butyl acetate. The method limit of quantitation was 0.03 μg/g for both D and ND. The concentrations of D and ND were highest in plasma and lowest in erythrocytes. The plasma/blood (P/B) distribution ratios did not depend on drug concentration between 0.1 and 1.0 μg/g. The mean P/B ratios were 1.79:1 for D and 1.69:1 for ND when hematocrit was 45%. Furthermore, the P/B ratio for D (y) was positively correlated with blood hematocrit (x) and the regression equation was y = 0.636 + 0.025x (r = 0.86, P < 0.001). A similar strong association was found between the P/B ratio and hematocrit for ND (r = 0.79). P/B ratios of D and ND, blood hematocrit, hemoglobin, and the water content differed between sexes (P < 0.001). The overall mean P/B ratios for D and ND were 1.69 ± 0.097 (± SD) and 1.62 ± 0.08 (P < 0.001, n = 66) respectively when the mean hematocrit was 42.9 ± 3.4 (± SD). For forensic purposes, it would be better to forgo making any conversion of a drug concentration measured in whole blood to that expected in plasma or serum, instead, therapeutic and toxic concentrations should be established for the actual specimens received.

  • 8.
    Jonsson, Anna K.
    et al.
    Natl Board Forens Med, Dept Forens Chem and Genet, Linkoping, Sweden.
    Spigset, Olav
    St Olavs Univ Hosp, Norway; Norwegian Univ Sci and Technol, Norway.
    Reis, Margareta
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Sickle Univ Hosp, Sweden.
    A Compilation of Serum Concentrations of 12 Antipsychotic Drugs in a Therapeutic Drug Monitoring Setting2019In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 41, no 3, p. 348-356Article in journal (Refereed)
    Abstract [en]

    Background: No comprehensive collection of routine therapeutic drug monitoring data for antipsychotic drugs has been published. Methods: In this compilation, data on 12 antipsychotics are presented. The drugs included are amisulpride (n = 506), aripiprazole (n = 1610), clozapine (n = 1189), flupentixol (n = 215), haloperidol (n = 390), olanzapine (n = 10,268), perphenazine (n = 1065), quetiapine (n = 5853), risperidone (n = 3255), sertindole (n = 111), ziprasidone (n = 1235), and zuclopenthixol (n = 691). Because only one sample per patient is included, the number of patients equals the number of samples. For each drug, median serum concentrations as well as that of the 10th and 90th percentiles are given for a range of daily doses. Comparisons are made between males and females, between patients younger than 65 years and 65 years and older, and between those treated with a low and a high dose of each drug. The concentration-to-dose (C/D) ratio is the primary variable used in these comparisons. Coefficients of variation (CVs) for the serum concentrations of each drug within and between subjects are presented. Results: In general, the C/D ratios were higher in females than in males, higher in those 65 years and older than in younger subjects, and lower in those treated with higher doses than in those treated with lower doses. CVs between individuals were larger than within subjects, and the CVs were highest for the drugs with short elimination half-lives. Conclusions: For each antipsychotic drug, the results presented can serve as a reference tool for pharmacokinetic interpretation of the individual patients serum drug level. The compiled serum concentrations and the C/D ratios can support the physicians decision when individualizing dosing and determining treatment strategies for a specific patient.

  • 9.
    Kronstrand, Robert
    et al.
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences.
    Forsman, Malin
    Natl Board Forens Med, Dept Forens Genet and Forens Toxicol, SE-58758 Linkoping, Sweden .
    Roman, Markus
    Natl Board Forens Med, Dept Forens Genet and Forens Toxicol, SE-58758 Linkoping, Sweden .
    A Screening Method for 30 Drugs in Hair Using Ultrahigh-Performance Liquid Chromatography Time-of-Flight Mass Spectrometry2013In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 35, no 3, p. 288-295Article in journal (Refereed)
    Abstract [en]

    Objectives: The objectives of this study were to develop and to validate a qualitative screening method that met the new Society of Hair Testing (SoHT) guideline criteria for thresholds. less thanbrgreater than less thanbrgreater thanMethods: Extraction of 20 mg hair was performed by a previously validated procedure using overnight incubation in a mixture of methanol:acetonitrile:formiate buffer pH 3 (10:10:80). Analysis was performed on an Agilent 6540 quadrupole time-of-flight mass spectrometer in combination with an Agilent 1290 Infinity ultrahigh-performance liquid chromatography system. Separation was achieved with a 12-minute linear gradient chromatography on a high-strength silica T3 column at acidic conditions. An in-house database containing 30 compounds from the groups amphetamines, opiates, opioids, cocaine, benzodiazepines, and other sedatives including 6 deuterated internal standards was built by analyzing solutions from certified standards. Data were extracted using mass accuracy of +/- 10 ppm, retention time deviation of +/- 0.15 minutes, and area of andgt;= 30,000 counts. Identification was based on scoring of retention time, accurate mass measurement, and isotopic pattern. Validation included selectivity, repeatability of analyte area, and the scoring parameters at the proposed thresholds and a method comparison with the present liquid chromatography-mass spectrometry-mass spectrometry method using 50 authentic hair samples. A daily cutoff calibrator was used to identify positive samples. less thanbrgreater than less thanbrgreater thanResults: All cutoffs could be met with imprecisions of less than 5% for most parameters and analytes. Hair from drug-free subjects did not produce any positive results and the method comparison agreed in more than 90% of the cases. less thanbrgreater than less thanbrgreater thanConclusions: We conclude that the developed method meets the criteria of the new SoHT guidelines for screening cutoffs. Even though no thresholds have been suggested for benzodiazepines, we conclude that thresholds between 0.05 and 0.1 ng/mg should be sufficient to determine regular use of these substances.

  • 10.
    Kugelberg, Fredrik
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology .
    Carlsson, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology .
    Ahlner, Johan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology .
    Bengtsson, Finn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology .
    Disposition of the enantiomers of citalopram and its demethylated metabolites in rats2003In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 25, no 4, p. 163-Conference paper (Other academic)
  • 11.
    Lofgren, C.
    et al.
    Löfgren, C., Department of Clinical Hematology, Karolinska University Hospital, Stockholm, Sweden, Department of Medicine, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden, Hematology Center Karolinska, M 54 Huddinge, Karolinska University Hospital, S-141 86 Stockholm, Sweden.
    Albertioni, Freidoun
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology .
    Paul, C.
    Department of Clinical Hematology, Karolinska University Hospital, Stockholm, Sweden, Department of Medicine, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden.
    High activity and incomplete cross resistance of nucleoside analogues cladribine and fludarabine versus ara-C on leukemic cells from patients with AML2005In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 27, no 5, p. 641-646Article in journal (Refereed)
    Abstract [en]

    The in vitro activity and cross-resistance pattern of the purine analogues cladribine and fludarabine and the pyrimidine analogue cytarabine on leukemic cells from 170 patients with AML was evaluated using a bioluminescence assay. In in vivo mimicking concentrations, cladribine (50 nmol/L) and fludarabine (2 µmol/L) were more cytotoxic than cytarabine (0.5 µmol/L). The cytotoxic effect of fludarabine correlated weakly to cytarabine (r = 0.37, P < 0.001). The cytotoxic effect of cladribine correlated better to cytarabine (r = 0.49, P = 0.0002) but best to fludarabine (r = 0.82, P < 0.001). There was an absence of correlation between either cladribine or fludarabine and daunorubicin (0.2 µmol/L). Of 45 highly Ara-C-resistant samples, cladribine exerted high or intermediate effect in 54% and fludarabine in 52%. These in vitro data indicate that cladribine and fludarabine are active drugs in the treatment of AML. The cross resistance to cytarabine was not complete, and the drugs can be valuable either as alternatives to Ara-C or in combination therapy for treatment of leukemia resistant to standard therapy. Copyright © 2005 by Lippincott Williams & Wilkins.

  • 12.
    Lundmark, Jöns
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Faculty of Health Sciences.
    Reis, Margareta
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Bengtsson, Finn
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Serum concentrations of fluoxetine in the clinical treatment setting2001In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 23, no 2, p. 139-147Article in journal (Refereed)
    Abstract [en]

    This article discusses fluoxetine serum concentrations as displayed in a clinical setting. A racemic serum fluoxetine and norfluoxetine high-performance liquid chromatography method, including ultraviolet light detection, was used for routine therapeutic drug monitoring (TDM) purposes. In all, 508 samples were analyzed. For the scientific investigation, predefined inclusion and exclusion criteria were applied and 150 samples representative of trough values in steady-state conditions with essential clinical information provided on the assay request forms were evaluated. Fluoxetine plus norfluoxetine concentration-to-dose (C/D) ratio showed Gaussian distribution. Interindividual coefficients of variation of fluoxetine and norfluoxetine serum concentrations after different doses were found to be 40-63%. Intraindividual fluoxetine TDM variability was low. The Spearman rank correlation coefficient for fluoxetine and norfluoxetine C/D ratios in first and second samples was 0.68. Minor increases in norfluoxetine C/D and fluoxetine plus norfluoxetine C/D ratios were found in elderly patients compared with younger adult patients. A higher body-mass index was associated with minor decreases in fluoxetine and fluoxetine plus norfluoxetine C/D ratios. New fluoxetine pharmacokinetic data are added to the results from earlier phases of drug development. Moreover, the results of this study support the usefulness of a fluoxetine TDM procedure for individual dose optimization, detection of drug interactions, and assessments of patient compliance.

  • 13.
    Lundmark, Jöns
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Faculty of Health Sciences.
    Reis, Margareta
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Bengtsson, Finn
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Therapeutic drug monitoring of sertraline: Variability factors as displayed in a clinical setting2000In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 22, no 4, p. 446-454Article in journal (Refereed)
    Abstract [en]

    This report describes sertraline pharmacokinetics derived from routine therapeutic drug monitoring (TDM) data. A high-performance liquid chromatographic method with ultraviolet detection was established for routine sertraline TDM, and 924 analyses were performed from April 1995 to May 1997. Extensive predefined inclusion/exclusion criteria were applied to increase the validity of scientifically evaluated data. Subsequently, 605 samples (65.5%) were excluded. The remaining 319 samples from 319 patients, representative of steady state through specimens and accompanied by essential clinical information provided on request forms, were scrutinized. A pronounced interindividual variability was observed. Smokers had significantly lower concentration-to-dose (C/D) mean ratios of serum sertraline (s-sert) and its main metabolite desmethylsertraline (s-dsert) than nonsmokers. Higher s-sert and s-dsert C/D mean ratios were found in elderly patients than in adults aged less than 65 years. In a subset of 20 patients in whom repeated TDM analyses were performed, observed intraindividual sertraline TDM outcome variability was low. The results highlight sertraline TDM as a tool for individual dose optimization and evaluation of patient drug compliance as well as drug-drug interactions.

  • 14. Pettersson, B
    et al.
    Almer, Sven
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Molecular and Clinical Medicine, Gastroenterology and Hepatology. Östergötlands Läns Landsting, MKC - Medicin och kirurgicentrum, EMK-magtarm.
    Albertioni, F
    Söderhäll, S
    Peterson, C
    Differences between children and adults in thiopurine methyltransferase activity and metabolite formation during thiopurine therapy: Possible role of concomitant methotrexate2002In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 24, no 3, p. 351-358Article in journal (Refereed)
    Abstract [en]

    This study examined the role of thiopurine methyltransferase (TPMT) polymorphism in the metabolism and clinical effects of azathioprine and 6-mercaptopurine in the treatment of inflammatory bowel disease and childhood leukemia. The current hypothesis is that the cytotoxic effects of thiopurines are caused by the incorporation of thioguanine nucleotides into DNA. In this context, S-methylation catalyzed by TPMT can be regarded as a competing metabolic pathway. The authors assayed the TPMT activity in red blood cells from 122 patients treated with azathioprine or 6-mercaptopurine (83 adults with inflammatory bowel disease and 39 children with acute lymphoblastic leukemia) and in 290 untreated controls (219 adult blood donors and 71 children). The concentrations of thioguanine nucleotides and methylthioinosine monophosphate were also assayed in red blood cells from the patients. The TPMT activity and the concentrations of methylthioinosine monophosphate and thioguanine nucleotides were higher in children than in adults. All children but no adult patient received concomitant methotrexate. Interaction between methotrexate and 6-mercaptopurine has been described, and may explain the results. Low TPMT activity in adult patients with inflammatory bowel disease correlated to an increased incidence of adverse drug reactions. However, there was no correlation between TPMT activity and the red blood cell concentrations of methylthioinosine monophosphate or thioguanine nucleotides, or between the concentrations of these metabolites and the occurrence of adverse effects. The results show that the role of thiopurine metabolism for drug effects is complex.

  • 15.
    Reis, Margareta
    et al.
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Cherma Yeste, Maria Dolores
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Carlsson, Björn
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Bengtsson, Finn
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Therapeutic Drug Monitoring of Escitalopram in an outpatient setting2007In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 29, no 6, p. 758-766Article in journal (Refereed)
    Abstract [en]

    The main objectives of this study were to outline the inter- and intraindividual and overall pharmacokinetic variability of S-citalopram, S-desmethylcitalopram, and S-didesmethylcitalopram in serum by means of therapeutic drug monitoring, and to investigate potential correlations between the serum concentration and simultaneously collected clinical data. The study was conducted on outpatients in Sweden in 2002 to 2005. Included in the pharmacokinetic evaluation were 155 patients (68% women and 32% men) aged 17 to 95 years (average, 51 years). One serum sample per patient, taken as a trough value in steady state, was assessed. For the inter- and intraindividual variation calculation, 16 patients were included with two eligible samples each. The median daily dose was 20 mg/day (range, 5-40 mg). Extensive overall serum concentration variability was seen for all dose levels. The interindividual coefficient of variation for dose-normalized concentrations was 71% for S-citalopram, 36% for S-desmethylcitalopram, and 50% for S- didesmethylcitalopram. The intraindividual variations over time for the same parameters were approximately 30%, except for the ratio S-desmethylcitalopram/S- citalopram, which was 23%. The median S-desmethylcitalopram level was approximately 60% of the parent substance and the S-didesmethylcitalopram level approximately 9%. Higher age was correlated with higher serum concentrations, but no gender-related concentration differences were found. A majority (76%) of the patients took one or more drugs in addition to escitalopram, but concomitant medication did not seem to interact with escitalopram. However, women taking oral contraceptives showed a lower metabolic ratio compared with age-matched women. As a result of the wide range of the ratio in this population, these findings are not considered of clinical relevance.

  • 16.
    Reis, Margareta
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Lundmark, Jöns
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Faculty of Health Sciences.
    Bengtsson, Finn
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Therapeutic drug monitoring of racemic citalopram: a 5-year experience in Sweden, 1992-19972003In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 25, no 2, p. 183-191Article in journal (Refereed)
    Abstract [en]

    Racemic citalopram (CIT) was introduced in Sweden in 1992 for management of major depression. During a 5-year period, 1992 to 1997, serum samples of CIT and desmethylcitalopram (DCIT) were collected for therapeutic drug monitoring (TDM) from patients from all over Sweden. These samples were accompanied by clinical information on a specially designed TDM request form. They represented men and women of various ages (11-94 years) usually on multiple concomitant medications and treated in a naturalistic setting. The TDM samples eligible for evaluation (n = 749), all trough values at steady state, were studied with respect to inter- and intraindividual pharmacokinetic variability. Extensive, interindividual serum concentration variability was seen on all dose levels. For dose-corrected concentrations (C/D) and for clearance (C1) we found the coefficient of variation (CV) to be approximately 55% for all variables (C/D CIT, C/D DCIT, the ratio DCIT to CIT, and for C1 CIT). The intraindividual variations over time for the same parameters were 30% to 35%. On a population level, signs of a possible saturation of CYP2D6 associated with increasing DCIT-to-CIT ratios with increasing daily doses was observed. Age and gender affected the pharmacokinetics of CIT and DCIT. Women showed significantly higher C/D CIT and C/D DCIT and lower C1 CIT values compared with men, and patients aged more than 65 years had higher C/D CIT and C/D DCIT and lower C1 CIT values compared with younger patients. Finally, concomitant medication affected the outcome of serum concentrations by a general increase in C/D CIT and C/D DCIT but without alteration in the DCIT-to-CIT ratio. Thus, this tendency of changes in the CIT disposition when multiple drugs are used (and multiple diseases are prevailing?) seems more general in character than specific for a certain drug or type of drugs.

  • 17.
    Reis, Margareta
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Faculty of Health Sciences.
    Lundmark, Jöns
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Faculty of Health Sciences.
    Björk, Henrik
    Department of Clinical Pharmacology, Lund University, Lund, Sweden.
    Bengtsson, Finn
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Faculty of Health Sciences.
    Therapeutic drug monitoring of racemic venlafaxine and its main metabolites in an everyday clinical setting2002In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 24, no 4, p. 545-553Article in journal (Refereed)
    Abstract [en]

    When Efexor® (venlafaxine) became available in Sweden, a therapeutic drug monitoring (TDM) service was developed in the authors' laboratory. This analytical service was available to all physicians in the country. From March 1996, to November 1997, 797 serum concentration analyses of venlafaxine (VEN) and its main metabolites, O-desmethylvenlafaxine (ODV), N-desmethylvenlafaxine (NDV), and N,O-didesmethylvenlafaxine (DDV) were requested. These samples, each of which was accompanied by clinical information on a specially designed request form, represented 635 inpatients or outpatients, comprising all ages, treated in a naturalistic setting. The first sample per patient, drawn as a trough value in steady state and with documented concomitant medication, was further evaluated pharmacokinetically (n= 187). The doses prescribed were from 37.5 mg/d to 412.5 mg/d. There was a wide interindividual variability of serum concentrations on each dose level, and the mean coefficient of variation of the dose-corrected concentrations (C/D) was 166% for C/D VEN, 60% for C/D ODV, 151% for C/D NDV, and 59% for C/D DDV. The corresponding CV for the ratio ODV/VEN was 110%. However, within patients over time, the C/D VEN and ODV/VEN variation was low, indicating stability in individual metabolizing capacity. Patients over 65 years of age had significantly higher concentrations of C/D VEN and C/D ODV than the younger patients. Women had higher C/D NDV and C/D DDV, and a higher NDV/VEN ratio than men, and smokers showed lower C/D ODV and C/D DDV than nonsmokers. A number of polycombinations of drugs were assessed for interaction screening, and a trend for lowered ODV/VEN ratio was found, predominantly with concomitant medication with CNS-active drug(s) known to inhibit CYP2D6.

  • 18.
    Reis, Margareta
    et al.
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Prochazka, Jiri
    Sitsen, Ad
    Ahlner, Johan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Bengtsson, Finn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Inter- and intraindividual pharmacokinetic variations of mirtazapine and its N-demethyl metabolite in patients treated for major depressive disorder: A 6-month therapeutic drug monitoring study2005In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 27, no 4, p. 469-477Article in journal (Refereed)
    Abstract [en]

    Mirtazapine pharmacokinetic (PK) data from patients on long-term treatment for major depression have never been investigated. For this reason, in a large naturalistic outpatient study (prospective, multicenter, open-labeled, and noncomparative) conducted in Sweden in the period 2000-2002, one of the main objectives was to outline the inter- as well as intraindividual PK variance of mirtazapine and demethylmirtazapine serum concentrations in a patient cohort treated up to 6 (optionally 12) months. A total of 192 male and female outpatients aged 18 years or older were included. Serum samples of mirtazapine and demethylmirtazapine were collected, by the means of therapeutic drug monitoring, at weeks 1, 4, 8, and 24 (52). Altogether 683 serum samples were analyzed. A pronounced interindividual variability of mirtazapine and demethylmirtazapine, and the demethylmirtazapine/mirtazapine ratio was seen. The coefficient of variation was about 38%, 33%, and 36%, respectively. The intraindividual variation over time was low, about 20% on all variables. At the population level, no accumulation of mirtazapine, demethylmirtazapine, or change of the demethylmirtazapine/mirtazapine ratio was observed over time. Women had significantly higher dose-corrected concentrations of mirtazapine and demethylmirtazapine and demethylmirtazapine/mirtazapine ratio than men. Patients above 65 years of age had higher concentrations than their younger counterparts. Among patients with adverse events, lower demethylmirtazapine concentrations were observed than in patients with no adverse events. Patients on multiple drug treatment had higher dose-corrected mirtazapine and demethylmirtazapine serum concentrations than patients taking only mirtazapine. Weight and BMI had a significant negative correlation with demethylmirtazapine concentrations and with the demethylmirtazapine/mirtazapine ratio. Continued efforts are warranted to perform PK studies in a natural clinical setting to learn and understand inter- and intraindividual PK variances in real patients treated for longer periods of time. For mirtazapine as well as for most antidepressant drugs only relatively short term PK is available. To help clinicians improve their treatment of patients with major depressive disorder, the possible implications on the PK with a long-term treatment are important to study. Copyright © 2005 by Lippincott Williams & Wilkins.

  • 19.
    Rosenqvist, Ulrika
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Psychiatry . Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Psychiatry.
    Tornqvist, M
    Bengtsson, Finn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology .
    An interaction between sertraline and carbamazepine which resluted in sub-therapeutic concentrations of sertraline and N-desmethylsertraline in serum2003In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 25, no 4, p. 166-Conference paper (Other academic)
  • 20.
    Skogh, Elisabeth
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Psychiatry.
    Bengtsson, Finn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Psychiatry.
    Nordin, Conny
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Psychiatry.
    Could discontinuing smoking be hazardous for patients administered clozapine medication? A case report.1999In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 21, p. 580-582Article in journal (Refereed)
  • 21.
    Skogh, Elisabeth
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Psychiatry.
    Reis, Margareta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Psychiatry.
    Dahl, Marja-Liisa
    Lundmark, Jöns
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Geriatrics. Östergötlands Läns Landsting, MC - Medicincentrum, Geriatrik-LAH.
    Bengtsson, Finn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Psychiatry.
    Therapeutic drug monitoring data on olanzapine and its N-demethyl metabolite in the naturalistic clinical setting2002In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 24, no 4, p. 518-526Article in journal (Refereed)
    Abstract [en]

    Olanzapine (Zyprexa«) was approved for general prescription in Sweden in November 1996, and an HPLC-based therapeutic drug monitoring (TDM) routine for serum olanzapine (OLA) and its major metabolite, N-demethylolanzapine (DMO) was established in February 1997. During 1997 to 1999, a total of 753 TDM requests for a total of 545 Swedish patients was analyzed. Additional patient information on certain clinical variables was collected on specifically designed TDM request forms. After the exclusion process, samples from 194 patients were found to be eligible for further scrutiny. The concentration-to-dose (C/D) ratio for OLA varied 25-fold and that of DMO 22-fold. Women had a higher (P < 0.01) median C/D ratio for OLA than men (median, 7.2 nmol/L/mg vs 5.2 nmol/L/mg). Nonsmokers had a higher (P < 0.001) C/D ratio for OLA than smokers (median, 9,2 nmol/L/mg vs 4.0 nmol/L/mg). Smokers got higher prescribed (P < 0.05) doses of OLA than nonsmokers did. In the group with reported side effects, the median serum OLA concentration was 22% higher (P < 0.05) than in the group without side effects. Patients co-medicated with carbamazepine had a 71% lower median C/D ratio for OLA than patients on OLA monotherapy. The present TDM-based follow-up suggests that the influence of gender, smoking habits, and certain drug interactions may need to be considered for optimal dosage of OLA. TDM may be used for this purpose more readily in the future.

  • 22.
    Skoglund, Karin
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Richter, Johan
    Skåne University Hospital, Sweden.
    Olsson-Stromberg, Ulla
    Uppsala University, Sweden.
    Bergquist, Jonas
    Uppsala University, Sweden.
    Aluthgedara, Warunika
    Uppsala University, Sweden.
    Ubhayasekera, S. J. Kumari A.
    Uppsala University, Sweden.
    Vikingsson, Svante
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Karolinska Institute, Sweden.
    Svedberg, Anna
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Söderlund, Stina
    Uppsala University, Sweden.
    Sandstedt, Anna
    Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Haematology.
    Johnsson, Anders
    Region Östergötland, Local Health Care Services in West Östergötland, Department of Medical Specialist in Motala.
    Aagesen, Jesper
    Ryhov County Hospital, Sweden.
    Alsenhed, Jonas
    Vastervik Hosp, Dept Internal Med, Västervik, Sweden.
    Hägg, Staffan
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Pharmacology.
    Peterson, Curt
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology.
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Haematology.
    Green, Henrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    In Vivo Cytochrome P450 3A Isoenzyme Activity and Pharmacokinetics of Imatinib in Relation to Therapeutic Outcome in Patients With Chronic Myeloid Leukemia2016In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 38, no 2, p. 230-238Article in journal (Refereed)
    Abstract [en]

    Background: Cytochrome P450 3A (CYP3A) isoenzyme metabolic activity varies between individuals and is therefore a possible candidate of influence on the therapeutic outcome of the tyrosine kinase inhibitor imatinib in patients with chronic myeloid leukemia (CML). The aim of this study was to investigate the influence of CYP3A metabolic activity on the plasma concentration and outcome of imatinib in patients with CML. Methods: Forty-three patients with CML were phenotyped for CYP3A activity using quinine as a probe drug and evaluated for clinical response parameters. Plasma concentrations of imatinib and its main metabolite, CGP74588, were determined using liquid chromatography-mass spectrometry. Results: Patients with optimal response to imatinib after 12 months of therapy did not differ in CYP3A activity compared to nonoptimal responders (quinine metabolic ratio of 14.69 and 14.70, respectively; P = 0.966). Neither the imatinib plasma concentration nor the CGP74588/imatinib ratio was significantly associated with CYP3A activity. Conclusions: The CYP3A activity does not influence imatinib plasma concentrations or the therapeutic outcome. These results indicate that although imatinib is metabolized by CYP3A enzymes, this activity is not the rate-limiting step in imatinib metabolism and excretion. Future studies should focus on other pharmacokinetic processes so as to identify the major contributor to patient variability in imatinib plasma concentrations.

  • 23.
    Skov-Skov Bergh, Marianne
    et al.
    Oslo Univ Hosp, Norway; Univ Oslo, Norway.
    Bogen, Inger Lise
    Oslo Univ Hosp, Norway; Univ Oslo, Norway.
    Wohlfarth, Ariane
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Wilson, Steven Ray
    Univ Oslo, Norway.
    Oiestad, Ase Marit Leere
    Oslo Univ Hosp, Norway.
    Distinguishing Between Cyclopropylfentanyl and Crotonylfentanyl by Methods Commonly Available in the Forensic Laboratory2019In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 41, no 4, p. 519-527Article in journal (Refereed)
    Abstract [en]

    Background: The opioid analgesic fentanyl and its analogues pose a major health concern due to its high potency and the increasing number of overdose deaths worldwide. The analogues of fentanyl may differ in potency, toxicity, and legal status, and it is therefore important to develop analytical methods for their correct identification. This can be challenging since many fentanyl analogues are structural isomers. Two fentanyl isomers that have been in the spotlight lately due to difficulties regarding separation and identification are cyclopropylfentanyl and crotonylfentanyl, which have been reported to display nearly identical fragmentation patterns and chromatographic behavior. Methods: Chromatographic separation of cyclopropylfentanyl and crotonylfentanyl by ultra-high-performance liquid chromatography was investigated using 3 different stationary phases (high strength silica T3, ethylsiloxane/silica hybrid C-18, and Kinetex biphenyl) using gradient elution with a mobile phase consisting of 10 mM ammonium formate pH 3.1 and MeOH. Detection was performed by tandem mass spectrometry. In addition, the major metabolites of the 2 compounds formed on incubation with human liver microsomes were identified by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry analysis. Results: Baseline separation of cyclopropylfentanyl and crotonylfentanyl was achieved on the ethylsiloxane/silica hybrid C-18 column with retention times of 6.79 and 7.35 minutes, respectively. The major metabolites of the 2 analogues formed by human liver microsomes differed, with the main biotransformation being N-dealkylation and carboxylation for cyclopropylfentanyl and crotonylfentanyl, respectively. We demonstrated the usefulness of the 2 approaches by unambiguously identifying cyclopropylfentanyl, as well as its metabolites, in 2 authentic postmortem blood samples. Conclusions: In this study, we successfully demonstrated that cyclopropylfentanyl and crotonylfentanyl can be distinguished by methods commonly available in forensic laboratories.

  • 24.
    Vikingsson, Svante
    et al.
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Carlsson, Björn
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Almer, Sven H C
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Endocrinology and Gastroenterology UHL.
    Peterson, Curt
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Oncology UHL.
    Monitoring of thiopurine metabolites in patients with inflammatory bowel disease-what is actually measured?2009In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 31, no 3, p. 345-50Article in journal (Refereed)
    Abstract [en]

    Azathioprine and 6-mercaptopurine are often used in the treatment of patients with inflammatory bowel disease (IBD). They are prodrugs and undergo a complex metabolism to active and inactive metabolites. Thiopurine treatment is monitored in many laboratories by measuring metabolite concentrations in erythrocytes (red blood cells). The metabolites of interest are not measured directly but as hydrolysis products, which can be produced from several metabolites. The aim of this study was to examine which metabolites are actually measured during routine monitoring. Samples from 18 patients treated with a thiopurine were analyzed by a typical routine high-performance liquid chromatography method for therapeutic drug monitoring and by a newly developed specific method measuring thioguanosine monophosphate (TGMP), thioguanosine diphosphate (TGDP), and thioguanosine triphosphate (TGTP), as well as methylthioinosine monophosphate (meTIMP), and the results were compared. 6-Thioguanine nucleotide (TGN) values detected by the routine method were 69% (range 40%-90%) of the sum of TGMP, TGDP, and TGTP measured by the specific method. TGTP and TGDP contributed 85% (range 78%-90%) and 14% (range 10%-21%) of the TGN total, respectively. Thioguanosine was not found in any patient sample. The concentration of meTIMP obtained by the routine method was 548% of the value obtained by the specific method (range 340%-718%). The difference in TGN measurements between the routine and specific methods can be explained by low hydrolysis efficiency in the routine method, although the most likely explanation for the difference in meTIMP values is that not yet identified metabolites are codetermined in the routine high-performance liquid chromatography method. Concentrations reported as TGN during therapeutic drug monitoring of thiopurine metabolites consist of TGDP and TGTP with a minor contribution of the TGMP. Concentrations reported as meTIMP or methyl mercaptopurine consist in part of meTIMP, but other not yet identified metabolites are codetermined.

  • 25.
    Öhman, Daniel
    et al.
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Cherma Yeste, Maria Dolores
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Norlander, Björn
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Bengtsson, Finn
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Determination of serum reboxetine enantiomers in patients on chronic medication with racemic reboxetine2003In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 25, no 2, p. 174-182Article in journal (Refereed)
    Abstract [en]

    The chiral compound reboxetine is used as a selective noradrenaline re-uptake inhibitor (NARI) for the treatment of major depressive disorders. The pharmacokinetic variability of the enantiomers of the drug (S,S- and R,R-reboxetine) was studied using stereoselective high-performance liquid chromatography with mass spectrometric detection in a controlled clinical monotherapy situation (trial I) and a naturalistic clinical setting (trial II). Trial I included patients receiving racemic reboxetine as 6-month monotherapy for treatment of major depressive disorder. Trough level serum samples in steady state were analyzed for the concentration of the reboxetine enantiomers in study weeks 4, 12, and 24. In a therapeutic drug monitoring setting (trial II), 47 patients on doses ranging from 4 to 16 mg daily, including much polypharmacy, trough level steady-state serum samples were analyzed by the same bioanalytical method. Data from trials I and II were assessed to determine the inter- and intraindividual pharmacokinetic outcomes. The results showed that the median S,S/R,R ratio in steady state was 0.5 and ranged from 0.22 to 0.88. It was also shown that women have an approximately 30% higher S,S/R,R ratio than men. The S,S/R,R ratios of reboxetine were not found to correlate with reboxetine concentrations. To investigate the NARI activity of a circulating serum reboxetine concentration, a recalculation of the determined enantiomeric concentrations to previously demonstrated experimental NARI potencies of the drug enantiomers was performed. This partly novel concept of estimating pharmacodynamic activity showed that the serum NARI activity in women tended to be higher than in men at a given reboxetine concentration. In conclusion, the variability in the NARI activity per nmol/L reboxetine and the variability in the concentration outcome of the reboxetine enantiomers may justify the use of enantioselective drug monitoring in the clinic. The gender aspects of the drug have to be further assessed.

  • 26.
    Öhman, Daniel
    et al.
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Norlander, Björn
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Peterson, Curt
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Bengtsson, Finn
    Linköping University, Department of Neuroscience and Locomotion, Psychiatry. Linköping University, Faculty of Health Sciences.
    Bioanalysis of racemic reboxetine and its desethylated metabolite in a therapeutic drug monitoring setting using solid phase extraction and HPLC2001In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 23, no 1, p. 27-34Article in journal (Refereed)
    Abstract [en]

    Reboxetine isa new antidepressant drug acting as a potent and selective noradrenaline reuptake inhibitor on the noradrenergic neuronal system. Because of an expected interindividual variability in drug metabolism in the clinical practice the need for therapeutic drug monitoring routines in psychiatry is always a prominent feature. In this application, the preferred bioanalytic methodology was solid phase extraction combined with reversed-Phase high-Performance liquid chromatography and ultraviolet detection at 210 nm. The technique proved reliable, with interday and intraday variation of less than 5% and a quantification limit for reboxetine and one of its main metabolites O-Desethylreboxetine (O-Reboxetine) at 5 and 30 nmol/L, respectively. The method was applied on serum samples from 38 patients treated chronically with reboxetine. These samples were drawn as trough levels in steady state with a dosage range of 2-16 mg/day. They evidenced a mean reboxetine concentration that was fairly linear and dose proportional, although the variance in concentration was large between patients, even those taking the same dosage. O-Reboxetine was detected in quantifiable amounts in only 1 of the 38 patients (<3%). In conclusion, these results suggest that a routine reboxetine therapeutic drug monitoring service that is robust enough to produce reliable and reproducible results may be introduced into everyday clinical practice.

1 - 26 of 26
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf