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Martin Josefsson

Publications and source records attributed to Martin Josefsson.

8 recordsLinked to original sources
PubMed2006

Sample preparation on polymeric solid phase extraction sorbents for liquid chromatographic-tandem mass spectrometric analysis of human whole blood--a study on a number of beta-agonists and beta-antagonists.

Alternative strategies for sample preparation of human blood samples were evaluated including protein precipitation (PP) and solid phase extraction (SPE) on Waters Oasis polymeric columns. Gradient chromatography within 15 min was performed on a Hypersil Polar-RP column combined with a Sciex API 2000 triple quadrupol instrument equipped with an electro-spray interface. Beta-agonists and beta-antagonists available on the Swedish market were included in the study. A combination of zinc sulphate and ethanol was found effective for PP. A clear supernatant was achieved that either could be injected directly on the LC-MS-MS system for analysis or transferred to a SPE column for further extraction and analyte concentration. Retention on the hydrophilic-lipophilic balanced sorbent HLB as well as the mixed mode cationic MCX and anionic MAX sorbents were investigated. On HBL the relative lipophilicity of the target analytes was investigated. At a high pH when the amino alcohols are deprotonised the more non-polar analytes (e.g., carvediol, betaxolol, bisoprolol and propranolol) were well retained on the sorbent and for the majority methanol content higher than 50% in water (v/v) was needed for elution. Some analytes though, with additional weak acidic functionalities (fenoterol, salbutamol, sotalol, and terbutaline) were poorly retained. On MAX the retention of these weak acids was improved when loaded under basic conditions but under neutral conditions analyte recoveries was comparable with HLB. On MCX all the analytes were well retained allowing a wash step of 100% methanol at neutral and low pH. By applying the supernatant from PP in combination with an additional portion of aqueous formic acid (2%) the analytes could be loaded and retained. High extraction recoveries were found for most analytes but for a few, significant losses were seen during PP (e.g., formoterol) and/or evaporation (e.g., fenoterol, formoterol, labetalol and terbutaline). The effectiveness of the sample preparation was evaluated by ESI ion-suppression studies by post column infusion of the target analyte. An ethanol zinc sulphate aq mixture was found to be more effective than acetonitrile, methanol or ethanol for PP of human whole blood samples. Beside suppression by salts in the front peak, only limited suppression from other artefacts such as more lipophilic compounds was found late in the chromatograms. Some tendency though to concentrate more lipophilic artefacts on the Oasis sorbents was seen. These findings show that the Oasis MCX sorbent is well suited for sample preparation of beta-agonists and beta-antagonists from human whole blood if the objective is to cover a great number of the analytes in the same assay.

Adrenergic beta-Agonists↗
PubMed2006

Tea flavanols inhibit angiotensin-converting enzyme activity and increase nitric oxide production in human endothelial cells.

A diversity of pharmacological effects on the cardiovascular system have been reported for Camellia sinensis: antioxidative, antiproliferative and anti-angiogenic activity, and nitric oxide synthase activation. The purpose of this study was to investigate if the connection between tea and angiotensin-converting enzyme (ACE) and nitric oxide (NO) might be an explanation of the pharmacological effects of tea on the cardiovascular system. Cultured endothelial cells from human umbilical veins (HUVEC) were incubated with extracts of Japanese Sencha (green tea), Indian Assam Broken Orange Pekoe (black tea) and Rooibos tea, respectively. The main flavanols and purine alkaloids in green and black tea were examined for their effects on ACE and NO. After incubation with green tea, black tea and Rooibos tea for 10 min, a significant and dose-dependent inhibition of ACE activity in HUVEC was seen with the green tea and the black tea. No significant effect on ACE was seen with the Rooibos tea. After 10-min incubation with (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechingallate and (-)-epigallocatechingallate, a dose-dependent inhibition of ACE activity in HUVEC was seen for all four tea catechins. After 24-h incubation, a significantly increased dose-dependent effect on NO production in HUVEC was seen for the green tea, the black tea and the Rooibos tea. After 24-h incubation with (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechingallate and (-)-epigallocatechingallate, a dose-dependent increased NO production in HUVEC was seen. In conclusion, tea extracts from C. sinensis may have the potential to prevent and protect against cardiovascular disease.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2003

Metabolism of salbutamol differs between asthmatic patients and healthy volunteers.

Patients with asthma are a target group for medication with beta2-agonists, often in combination with corticosteroids. Salbutamol is commonly marketed as racemate. R-Salbutamol carries beta2-agonistic property whereas S-salbutamol does not. The racemate undergoes stereoselective sulphatisation by sulfotransferases mainly in the gut and liver, so that S-salbutamol rests for a longer time in the body and reaches higher plasma levels than R-salbutamol. Ten patients with mild stable asthma and at present without cortisone medication were given racemic salbutamol as ventoline 4 mg orally. Plasma and urine levels were estimated until 24 hr after ingestion. For comparison healthy volunteers were treated in the same way. The group of asthma patients was then treated with budesonide inhalations 800 microg daily for one week and the initial programme resumed. Non-cortisone-treated asthmatic patients displayed higher levels of both R- and S-salbutamol in plasma than did healthy volunteers after one single ingestion of racemic salbutamol (CMAX both comparisons P<0.05). Plasma levels of salbutamol isomers in cortisone-treated asthmatic patients resembled the levels in volunteers. The most plausible explanation for the discrepancy in values between asthmatic patients and volunteers is a defective metabolic function by asthmatic patients possibly enzymatic in origin.

Adrenergic beta-Agonists↗
PubMed2003

Preserved bronchial dilatation after salbutamol does not guarantee protection against bronchial hyperresponsiveness.

Racemic salbutamol, a beta2-adrenoceptor agonist used for dilatation of airways, has recently been shown to induce lessened relaxation of bronchial smooth muscle and partial loss of bronchoprotection, seen as increased hyperresponsiveness, after regular treatment. The racemate undergoes stereo-selective disposition, giving higher plasma levels of S-salbutamol than that of bronchodilating R-salbutamol, thus raising S : R ratios after repeated administration. Our aim was to evaluate whether increased bronchial hyperresponsiveness (BHR) could be found even after 1 day of repeated salbutamol inhalations, with beta2-receptor-induced bronchial smooth muscle relaxation remaining and whether this would be associated with plasma levels of either enantiomer. Fifteen patients with stable asthma, aged 19-54 years, were included in a randomized, cross-over study. An indirect bronchial challenge method was used [voluntary isocapnic hyperventilation of cold air (IHCA)], and airway condition tested by means of impulse oscillometry. Racemic salbutamol was inhaled three times during a 6-h period. IHCA was performed and plasma concentrations of enantiomers were measured 4 h after the last dose. Tests were also performed without preceding drug treatment. beta2-Agonist-produced bronchial dilatation and protection persisted in the majority of the 15 patients 4 h after repeated inhalations of salbutamol during 1 day. In only two of the 15 patients we could trace increased BHR after salbutamol. Neither dilatation nor protection could be linked to plasma levels of either R- or S-salbutamol. The underlying mechanisms of BHR remain unknown and are dissociated from beta2-receptor-mediated dilatation.

Adrenergic beta-Agonists↗
PubMed2003

Analysis of buprenorphine, norbuprenorphine, and their glucuronides in urine by liquid chromatography-mass spectrometry.

Buprenorphine is used for the treatment of chronic pain and also in treatment of heroin addiction as an alternative to methadone. As the availability of buprenorphine increases, so does the risk for abuse and the pressure on forensic and clinical laboratories to analyze for it. Buprenorphine and its dealkylated metabolite are excreted in urine, almost exclusively as glucuronides. The aim of the present study was to evaluate electrospray liquid chromatography tandem mass spectrometry (LC-MS-MS) for the rapid screening and quantitation of buprenorphine and its metabolites in urine. Three approaches were evaluated: (1) direct injection of diluted urine for measurement of glucuronides, (2) direct injection of diluted urine after enzymatic hydrolysis for the quantitation of buprenorphine and norbuprenorphine, and (3) quantitation of buprenorphine and norbuprenorphine after enzymatic hydrolysis and solid-phase extraction (SPE). One hundred six samples were subjected to procedure 1 and, when positive, further quantitated using procedure 2. Only samples with low analyte concentrations (< 20 microg/L) were subject to SPE. Concentrations of buprenorphine and norbuprenorphine in patients (N = 16) ranged between 31 and 1080 microg/L and 48-2050 microg/L, respectively. In suspected abusers (N = 33), the ranges were 2.3-796 microg/L and 5.0-2580 microg/L. In four of the authentic samples, both the buprenorphine and norbuprenorphine concentrations were below the 20- micro g/L cutoff. We concluded that LC-MS-MS analysis of the glucuronides provided an adequate screening method, but that the direct method for quantitation sometimes had to be complemented with a concentration by SPE, providing increased sensitivity, thus lowering the cutoff from 20 to 1 microg/L urine.

Buprenorphine↗
PubMed2002

Disposition of venlafaxine enantiomers in rats with hepatic encephalopathy after chronic drug treatment.

Portacaval shunted (PCS) rats, a model of hepatic encephalopathy, and control animals were administered racemic venlafaxine for 14 days (10 mg/kg). The levels of the S- and R-enantiomers and the S/R-enantiomer ratios of venlafaxine and its metabolites were assessed by an enantiomer-selective chromatographic assay in serum, brain parenchyma, and brain dialysate of both groups. Higher levels of the S- and R-enantiomers of venlafaxine were found in serum and brain of PCS vs. normal rats (median values of S- and R-venlafaxine in serum: 290 and 201 nM in PCS; 97 and 66 nM in normal rats; median values of S- and R-venlafaxine in cortex: 956 and 939 nM in PCS; 357 and 318 nM in normal rats). Interestingly, similar S/R-venlafaxine ratios were observed in PCS and normal rats both in serum (S/R = 1.4) and brain compartments (S/R = l.0-1.1). These findings may have clinical relevance for the safety of venlafaxine in chronic hepatic encephalopathy.

Animals↗
PubMed2002

Segmental ion spray LC-MS-MS analysis of benzodiazepines in hair of psychiatric patients.

The aim of this study was to develop a liquid chromatography-tandem mass spectrometry (LC-MS-MS) method for the analysis of benzodiazepines in human hair. The method was tested by analyzing hair samples from forensic and clinical psychiatric patients where benzodiazepines had been prescribed during hospitalization and after care. Hair samples were obtained at discharge from the clinic and then after six months. Two-centimeter segments of the hair samples (10-30 mg) were washed once with isopropanol, three times with phosphate buffer, and again with isopropanol, dried, weighed, and digested with proteinase K before solid-phase extraction with BondElut Certify columns. Diazepam, nordiazepam, oxazepam, alprazolam, OH-alprazolam, nitrazepam, 7-aminonitrazepam, flunitrazepam, 7-aminoflunitrazepam, clonazepam, and 7-aminoclonazepam were quantitated in MRM mode using one transition for each analyte and deuterated internal standard. The calibration range was 0.125-5 ng/mg for diazepam, nordiazepam, and oxazepam and 0.025-1.0 ng/mg for the other compounds. In the hair samples analyzed, diazepam, flunitrazepam, nitrazepam, and clonazepam was detected together with their metabolites. Alprazolam was not detected in any sample. Segmental hair analysis revealed differences in drug deposition in hair before and after release from psychiatric treatment. Both increases and decreases of hair drug concentrations were seen after release even though the prescribed dose was the same. This was taken as an indication of noncompliance during the after-care period. We conclude that the extraction and LC-MS-MS procedures were adequate to detect benzodiazepines in hair and that the results indicated that segmental hair analysis might provide retrospective information about medication intake.

Antipsychotic Agents↗