Determination of fluvoxamine and its metabolite fluvoxamino acid by liquid-liquid extraction and column-switching high-performance liquid chromatography.

This study describes a new simultaneous determination of fluvoxamine and fluvoxamino acid by automated column-switching high-performance liquid chromatography. The test compounds were extracted from 1.5 ml of plasma using chloroform-toluene (15:85, v/v), and the extract was injected into a hydrophilic metaacrylate polymer column for clean-up and a C18 analytical column for separation. The mobile phase for separation consisted of phosphate buffer (0.02 M, pH 4.6), acetonitrile and perchloric acid (60%) (62.4:37.5:0.1, v/v/v) and was delivered at a flow rate of 0.6 ml/min. The peak was detected using a UV detector set at 254 nm. The method was validated for the concentration range 0.8-153.6 ng/ml for fluvoxamine and 0.6-115.2 ng/ml for fluvoxamino acid, and their good linearity (r > 0.998) were confirmed. Intra-day coefficient variations (CVs) for fluvoxamine and fluvoxamino acid were less than 6.6 and 6.0%, respectively. Inter-day CVs for corresponding compounds were 6.3 and 6.5%, respectively. Relative errors ranged from -18 to 9% and mean recoveries were 96-100%. The limit of quantification was 1.2 and 0.9 ng/ml for fluvoxamine and fluvoxamino acid, respectively. This method shows successful application for pharmacokinetic studies and therapeutic drug monitoring.

Relationship between clinical effects of fluvoxamine and the steady-state plasma concentrations of fluvoxamine and its major metabolite fluvoxamino acid in Japanese depressed patients.

OBJECTIVES: The relationship between clinical effects of fluvoxamine (FLV) and the steady-state plasma concentrations (Css) of FLV and its major metabolite fluvoxamino acid (FLA) was studied. METHODS: The subjects were 49 Japanese patients with major depressive disorder receiving FLV 200 mg/day for 6 weeks. Depressive symptoms and side effects were evaluated by the Montgomery Asberg Depression Rating Scale (MADRS), and the UKU Side Effect Rating Scale, respectively. The Css of FLV and FLA were measured by HPLC, and the CYP2D6 genotyping was performed by PCR methods. RESULTS: The Css of FLV and FLV+FLA showed significant negative correlations with the final MADRS score. The Css of FLV, FLA and FLV+FLA were significantly higher in the responders (final MADRS score < or =10) than in non-responders. The proportion of responders was significantly higher in the patients with the Css of FLV, FLA and FLV+FLA above 150, 55 and 180 ng/ml, respectively. In the multiple regression, the Css of FLV+FLA showed a significant negative correlation with the final MADRS score. In the logistic regression, the Css of FLA had a significant effect on the differentiation of responders from non-responders. The incidence of side effects was low, and the development of nausea, the most frequent one, was not dependent on any Css. The number of mutated CYP2D6 alleles causing absent or decreased enzyme activity was not related to the therapeutic response or development of nausea. CONCLUSIONS: The present study suggests that there is a therapeutic threshold for the Css of FLV and probably also for the Css of FLA, and the Css of FLV+FLA above 180 ng/ml best predicts a good therapeutic response.

Evaluation of [O-methyl-(11)C]fluvoxamine as a tracer for serotonin re-uptake sites.

We evaluated [(11)C]fluvoxamine as a tracer for the serotonin re-uptake site. Studies of the distribution of the tracer in rat and primate brain showed adequate uptake of [(11)C]fluvoxamine, but failed to reveal regions with known high density of serotoninergic re-uptake sites. Pretreatment with unlabeled fluvoxamine did not substantially change the distribution. In rat brain tissue, nearly all radioactivity represented intact [(11)C]fluvoxamine. [(11)C]Fluvoxamine does not function as a tracer for serotonin re-uptake sites, owing to high nonspecific binding in the brain.

High-performance liquid chromatographic determination of fluvoxamine and fluvoxamino acid in human plasma.

A high-performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination of fluvoxamine and its major metabolite fluvoxamino acid in plasma. Fluvoxamine and fluvoxamino acid in plasma were extracted using a C18 bonded-solid phase cartridge, followed by C4 reversed-phase HPLC separation.Fluvoxamine, fluvoxamino acid and moperone as an internal standard were detected by ultraviolet absorbance at 254 nm. It was possible to determine both fluvoxamine and fluvoxamino acid in the concentration range of 25.0-200.0 ng/mL, respectively. The detection limits of both fluvoxamine and fluvoxamino acid were 10.0 ng/mL, respectively. The mean recoveries of fluvoxamine and fluvoxamino acid added to plasma were more than 94.0% and 96.5%, with a coefficient of variation of less than 7.6% and 8.2%, respectively. This method has been used for the simultaneous determination of steady-state plasma concentration (Css) of fluvoxamine and fluvoxamino acid in depressive patients treated with 200 mg of oral fluvoxamine dosed as 100 mg twice-daily. The Css values of fluvoxamine and fluvoxamino acid in twelve Japanese patients were showed individual variations, which were in the range of 48.3-532.9 ng/ml and 35.6-307.1 ng/ml, respectively.

Synthesis of [O-methyl-11C]fluvoxamine--a potential serotonin uptake site radioligand.

5-Methoxy-1-[4-(trifluoromethyl)-phenyl]-1-pentanone-O-(2-aminoethyl)oxi me (fluvoxamine), a potent clinically used antidepressant, was labelled with carbon-11 (t1/2 = 20.4 min) as a potential radioligand for the non-invasive assessment of serotonin uptake sites in the human brain with positron emission tomography (PET). The two-step radiochemical synthesis consisted of O-methylation of an amino-protected desmethyl precursor with [11C]methyl iodide under mild conditions in the presence of tetrabutylammonium hydroxide in acetonitrile, followed by deprotection with trifluoroacetic acid. 5-[11C]Methoxy-1-[4-(trifluoromethyl)-phenyl]-1-pentanone-O-(2-aminoethy l) oxime was obtained in > 98% radiochemical purity in 40 min with a radiochemical yield of 4 +/- 2% (non-decay corrected) and a specific radioactivity of 1 +/- 0.5 Ci/mumol. 5-Hydroxy-1-[4-(trifluoromethyl)-phenyl]-1-pentanone-O-[2- (tert-butoxycarbonylamino)ethyl]oxime, the precursor for the radiosynthesis of [11C]fluvoxamine, was prepared by a convenient three-step synthesis from the pharmaceutical form of fluvoxamine maleate by converting it into the free base, demethylation by trimethyliodosilane and introduction of the BOC-protective group with di-tert-butyl dicarbonate.

Effects of PB190 and PB212, new σ receptor ligands, on glucocorticoid receptor-mediated gene transcription in LMCAT cells.

The hyperactivity of the hypothalamic-pituitary-adrenocortical (HPA) axis is often observed in patients with major depression. It has even been implicated in the pathophysiology of this disease. Some antidepressant drugs (ADs) inhibit glucocorticoid receptor (GR) function under in vitro conditions. The σ(1) receptor agonists reveal potential antidepressant activity in animals, moreover, igmesine is promising as an AD in humans. As already shown, σ receptors are involved in stress-induced responses (e.g., conditioned fear stress in mice). The aim of the present study was to find out whether the new selective σ receptor ligands, PB190 and PB212, are able to affect directly the endocrine system activity. To this end, we evaluated their influence on GR function in mouse fibroblast cells (L929), stably transfected with mouse mammary tumor virus-chloramphenicol acetyltransferase (MMTV-CAT) plasmid (LMCAT cells). Fluvoxamine, a selective serotonin reuptake inhibitor, recognized as a σ(1) receptor agonist was used for comparison. The obtained results showed that both PB190 and PB212 (potential σ(1) receptor agonist and antagonist, respectively) like fluvoxamine, decreased the corticosterone-induced CAT activity in a concentration-dependent manner. The significance of this fact remains ambiguous and requires further studies.

Identification of human cytochrome P450 enzymes involved in the major metabolic pathway of fluvoxamine.

The metabolism of fluvoxamine to fluvoxamino acid is known to involve a two-step oxidation process via an alcohol intermediate, fluvoxamino alcohol. The present study was carried out to identify the cytochrome P450 (CYP) enzyme(s) involved in the metabolism offluvoxamine to fluvoxamino alcohol using human liver microsomes and cDNA-expressed human CYP enzymes. The mean Km and Vmax values for the formation of fluvoxamino alcohol from fluvoxamine in human liver microsomes were 76.3 microM and 37.5 pmol min(-1) mg(-1) protein, respectively. The formation of fluvoxamino alcohol from fluvoxamine in pooled human liver microsomes was significantly inhibited by quinidine, a relatively specific CYP2D6 inhibitor, with a Ki value of 2.2 microM, whereas other several relatively specific CYP inhibitors did not inhibit the formation of fluvoxamino alcohol. In addition, only CYP2D6 of several cDNA-expressed human CYP enzymes examined showed substantial activity for the formation of fluvoxamino alcohol. Furthermore, the formation of fluvoxamino acid from fluvoxamino alcohol is potently inhibited by 4-methylpyrazole in human liver cytosol. These data suggest that CYP2D6 is the only enzyme predominantly responsible for the first-step oxidation of fluvoxamine to fluvoxamino alcohol, and alcohol dehydrogenase is involved in the second-step oxidation of fluvoxamino alcohol to the corresponding carbolic acid.

Effects of caffeine on the kinetics of fluvoxamine and its major metabolite in plasma after a single oral dose of the drug.

The effects of caffeine on the kinetics of fluvoxamine (FLV) and its major metabolite fluvoxamino acid (FLA) in plasma, after a single oral dose of the drug, were studied in 12 healthy male volunteers. The subjects received caffeine 300 mg/d or placebo for 11 days in a double-blind randomized crossover manner, and on the eighth day they received a single oral 50-mg dose of FLV. Blood sampling and pharmacodynamic evaluation were conducted up to 72 hours after FLV dosing. Plasma concentrations of FLV and FLA were measured by high-performance liquid chromatography. Caffeine significantly decreased the plasma concentrations at 6 time points (P<0.05) and total area under the plasma concentration-time curve (156.5+/-51.7 vs. 118.9+/-38.2 ng/h/mL, P<0.01) of FLV. Plasma concentration and pharmacokinetic parameters of FLA were not affected by caffeine. Caffeine induced no significant change in the pharmacodynamic effects of FLV. The present study suggests that caffeine slightly induces the metabolism of FLV, probably mediated by CYP1A2.

[Therapeutic action and efficiency of fevarin (fluvoxamine) in patients with non-psychotic anxious and apathic-adynamic depressions]. / Terapevticheskoe deistvie i éffektivnost' fevarina (fluvoksamina) u bol'nykh s nepsikhicheskimi trevozhnymi i apatoadinamicheskimi depressiiami.

10 patients with anxious and 10 patients with apathic-adynamic depressions were treated with fevarin. The efficiency of the drug and its influence on the psychopathologic structure were evaluated according to some scales. It was established that therapeutic action of fevarin manifests from the 1st week of therapy in patients with anxious depressions due to its anxiolytic properties. In apathic-adynamic depressions the reduction of the symptoms was revealed by the 3-4 week of the therapy. The antidepressive effect of fevarin was retarded and didn't depend on the structure of the depression. Higher efficiency of the drug in patients with anxious depressions was explained by combination of thymoanaleptic and anxiolytic effects. The results of the study demonstrate a perspective of fevarin in therapy of anxious and apathic-adynamic depressions.