ABSTRACT
BACKGROUND: An enantioselective analytical method was developed and validated for determination of venlafaxine and its metabolites O-desmethylvenlafaxine and N-desmethylvenlafaxine in plasma samples. The method employed LC-MS/MS analysis and hollow-fiber liquid-phase microextraction (HF LPME) for sample preparation. RESULTS: After HF LPME optimization the following condition was established: sample volume of 4 ml, sample agitation at 1750 rpm, 20 min of extraction, 0.1 mol/l acetic acid as acceptor phase, 1-octanol as organic phase and donor phase pH adjustment to 10. Under these conditions, the method was linear over the concentration range of 5-500 ng/ml with quantification limits of 5 ng/ml. CONCLUSION: The use of HF LPME for sample preparation provided suitable recoveries, efficient clean-up and low consumption of organic solvent.
Subject(s)
Antidepressive Agents, Second-Generation/blood , Chromatography, High Pressure Liquid , Cyclohexanols/blood , Liquid Phase Microextraction/methods , Tandem Mass Spectrometry , 1-Octanol/chemistry , Antidepressive Agents, Second-Generation/metabolism , Antidepressive Agents, Second-Generation/standards , Calibration , Chromatography, High Pressure Liquid/standards , Cyclohexanols/isolation & purification , Cyclohexanols/metabolism , Cyclohexanols/standards , Desvenlafaxine Succinate , Humans , Hydrogen-Ion Concentration , Liquid Phase Microextraction/instrumentation , Liquid Phase Microextraction/standards , Stereoisomerism , Tandem Mass Spectrometry/standards , Venlafaxine HydrochlorideABSTRACT
Lymphocytes from human peripheral blood exhibit a series of markers of neurotransmitters, such as specific receptors and transporters. A reduction of serotonin transporters and an increase of them has been reported after treatment with fluoxetine in depressed patients. The aim of this study was to determine if the administration of an antidepressant with a different mechanism of action, such as mirtazapine, could produce a similar effect. Twenty eight patients (age 41.40+/-2.45) were diagnosed following the criteria for major depression by the Structured Clinical Interview for Disorders of Axis I of the American Psychiatric Association. Severity was measured by Hamilton Scale and by Beck Inventory for Depression, scores of 30.88+/-7.48 and 30.24+/-10.88, respectively, prior to treatment. Samples from control subjects were obtained alternating with patients before and after the administration of the antidepressant: twenty eight and twenty four, respectively (age 38.80+/-2.95). Mirtazapine was given in a dose of 30 mg/day for 6 weeks. Blood lymphocytes were isolated by density gradient from patients and controls before and after treatment. There was a partial response according to clinical evaluation and scores of the Scale and the Inventory. Serotonin transporters were labeled with [3H] paroxetine. Number of sites (B(max)) were 10.86+/-2.60 and 12.58+/-2.71 fmol/10(6) cells for both groups of controls. The depressed patients had a significant reduction of serotonin transporters in their lymphocytes before treatment and an increase after it, with B(max) values of 6.52+/-0.49 and 15.61+/-0.49 fmol/10(6) cells, respectively. There were no significant differences in the affinity for the ligand. Concentrations of serotonin or noradrenaline in lymphocytes were not modified before the treatment, although there was a significant decrease after taking 30 mg/day of the antidepressant for 6 weeks. Mirtazapine, not being a serotonin reuptake inhibitor, did increase the number of transporters in lymphocytes of major depression patients, indicating a complex mechanism, not only directly related to the transporter, but involved in the therapeutic response.
Subject(s)
Antidepressive Agents, Tricyclic/pharmacology , Depressive Disorder, Major/metabolism , Lymphocytes/metabolism , Membrane Glycoproteins/metabolism , Membrane Transport Proteins/metabolism , Mianserin/analogs & derivatives , Mianserin/pharmacology , Nerve Tissue Proteins/metabolism , Adult , Antidepressive Agents, Second-Generation/metabolism , Cell Membrane/drug effects , Cell Membrane/metabolism , Depressive Disorder, Major/blood , Female , Humans , Hydroxyindoleacetic Acid/metabolism , Kinetics , Lymphocytes/drug effects , Male , Membrane Glycoproteins/blood , Membrane Transport Proteins/blood , Middle Aged , Mirtazapine , Nerve Tissue Proteins/blood , Norepinephrine/metabolism , Paroxetine/metabolism , Psychiatric Status Rating Scales , Serotonin/metabolism , Serotonin Plasma Membrane Transport ProteinsABSTRACT
Fluoxetine, a serotonin re-uptake inhibitor with antidepressive and appetite reduction effects, could improve insulin sensitivity. The aim of this work was to assess this effect of fluoxetine in obese subjects. We studied 12 subjects with a body mass index over 30, with a normal oral glucose tolerance test and not subjected to dietary restrictions. Insulin sensitivity using Bergman's minimal model, sex hormone binding globulin (SHBG) and insulin like growth factor binding protein 1 (BP 1) were evaluated before and after three weeks of treatment with 60 mg OD of fluoxetine. During treatment, subjects lost a mean of 1.9 kg. When compared with basal values, insulin sensitivity index (S1) improved significantly at the end of treatment (1.71 +/- 0.44 and 2.72 +/- 0.63 respectively), SHBG increased (28.9 +/- 5.1 and 18.2 +/- 3.4 nM/ml respectively) and BP 1 did not change (2.8 +/- 0.9 and 1.5 +/- 0.3 ng/ml respectively). The changes in insulin sensitivity did not correlate with weight changes (r = 0.4 NS). Weight or insulin sensitivity changes did not correlate with initial degree of insulin resistance. We conclude that the improvement in insulin sensitivity elicited by Fluoxetine is not related to weight changes and may be useful in the treatment of insulin resistant obese subjects.