Anal Bioanal Chem. 2003 Nov;377(5):880-5. Epub 2003 Sep 03.
Rapid analysis of fluoxetine and its metabolite in plasma by LC-MS with column-switching approach.

Souverain S, Mottaz M, Cherkaoui S, Veuthey JL.

Laboratory of Analytical Pharmaceutical Chemistry, School of Pharmacy, University of Geneva, 20 bvd d'Yvoy, 1211, Geneva 4, Switzerland.

A rapid and sensitive method was developed for the simultaneous determination of fluoxetine and its primary metabolite, norfluoxetine, in plasma. It was based on a column-switching approach with a precolumn packed with large size particles coupled with a liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS). After a simple centrifugation, plasma samples were directly injected onto the precolumn. The endogenous material was excluded thanks to a high flow rate while analytes were retained by hydrophobic interactions. Afterwards, the target compounds were eluted in back flush mode to an octadecyl analytical column and detected by ESI-MS. The overall analysis time per sample, from plasma sample preparation to data acquisition, was achieved in less than 4 min. Method performances were evaluated. The method showed good linearity in the range of 25-1000 ng mL(-1) with a determination coefficient higher than 0.99. Limits of quantification were estimated at 25 ng mL(-1) for fluoxetine and norfluoxetine. Moreover, method precision was better than 6% in the studied concentration range. These results demonstrated that the method could be used to quantify target compounds. Finally, the developed assay proved to be suitable for the simultaneous analysis of fluoxetine and its metabolite in real plasma samples.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12955393&dopt=Abstract fluoxetine




Synapse. 2003 Dec 15;50(4):353-64.
Characterization of fluoxetine plus olanzapine treatment in rats: a behavior, endocrine, and immediate-early gene expression analysis.

Horowitz JM, Goyal A, Ramdeen N, Hallas BH, Horowitz AT, Torres G.

Clinical Neuroscience Laboratory, Department of Psychology, Medaille College, Buffalo, New York 14214, USA.

A large number of individuals afflicted with psychiatric disorders, particularly depression with psychotic features, do not respond to conventional drug therapy. An option for this phenomenon is to augment a standard selective serotonin (5-HT) reuptake inhibitor with an atypical antipsychotic agent. In this regard, fluoxetine and olanzapine have been used concomitantly for treatment-resistant depression and bipolar depression. Although highly efficacious in terms of producing superior improvement of symptoms across a variety of psychological measures, the motor patterns, endocrine profiles, and intracellular signaling pathways affected by drug augmentation have not been determined. Here we show that fluoxetine (10 mg/kg) plus olanzapine (5 mg/kg) given to rats for 7 consecutive days (i.e., subchronic treatment) alters motor activity and diminishes spontaneous behaviors as measured by spatial position and angular path analyses. In addition, the same drug combination pattern sensitizes peak adrenal corticosterone secretion without altering serum glucose levels. We also show that subchronic fluoxetine and olanzapine exposure suppresses the induction of two immediate-early gene transcription factors (e.g., pCREB and FOS) that are associated with long-lasting changes in synaptic efficacy and structural modifications in the prefrontal cortex, piriform cortex, and hippocampus. These results suggest that fluoxetine plus olanzapine can interact in a fashion not predicted by the currently accepted model of fluoxetine monotherapy and provide insight into the synergistic actions of drug augmentation in patients with treatment-resistant depression. Copyright 2




Am J Physiol Regul Integr Comp Physiol. 2004 Feb;286(2):R390-7. Epub 2003 Nov 06.
Fluoxetine-induced changes in body weight and 5-HT1A receptor-mediated hormone secretion in rats on a tryptophan-deficient diet.

D'Souza DN, Zhang Y, Garcia F, Battaglia G, Van de Kar LD.

Dept. of Pharmacology, Loyola Univ. of Chicago, School of Medicine, 2160 South First Ave., Maywood, IL 60153, USA.

Tryptophan depleting protocols are commonly used to study the role of serotonin in mood disorders. The present study examined the impact of a tryptophan-deficient diet and fluoxetine on the serotonergic regulation of neuroendocrine function and body weight. We hypothesized that the regulation of postsynaptic 5-HT1A receptors is dependent on the levels of 5-HT in the synapse. Rats on a control or a tryptophan-deficient diet received daily injections of saline or fluoxetine (5 or 10 mg.kg-1.day-1 ip) from day 7 to day 21. The tryptophan-deficient diet produced a 41% reduction in the level of 5-HT but no change in the density of [3H]paroxetine-labeled 5-HT transporters. Treatment with fluoxetine inhibited the gain in weight in rats maintained on the control diet. The tryptophan-deficient diet produced a significant loss in body weight that was not significantly altered by treatment with fluoxetine. Treatment with fluoxetine produced a dose-dependent desensitization of hormone responses to injection of the 5-HT1A receptor agonist (+/-)8-hydroxy-2-(di-n-propylamino)tetralin ((+/-)8-OH-DPAT). The tryptophan-deficient diet produced an increase in the basal levels of corticosterone but did not alter the basal levels of ACTH or oxytocin. Also, this diet inhibited the magnitude of 8-OH-DPAT-induced increase in plasma levels of ACTH and oxytocin but did not impair the ability of fluoxetine to desensitize the 5-HT1A receptor-mediated increase in plasma hormones. These data suggest that a reserve of 5-HT enables fluoxetine to desensitize postsynaptic 5-HT1A receptors in the hypothalamus. In conclusion, the profound physiological changes induced by tryptophan depletio




Psychopharmacol Bull. 2003 Summer;37(3):90-8.
Economic impact of olanzapine plus fluoxetine combination therapy among patients treated for depression: a pilot study.

Corey-Lisle PK, Birnbaum H, Greenberg P, Marynchenko M, Dube S.

Eli Lilly and Company, Indianapolis, IN, USA.

Individuals with treatment-resistant depression (TRD) utilize more health care services and are significantly more costly. Drug treatments for TRD may include concomitant administration of multiple antidepressants or augmentation with mood stabilizers or antipsychotic agents. An augmentation strategy currently under investigation is the use of an olanzapine plus fluoxetine combination (OFC) therapy. The objectives for this pilot study were to use claims data to: (1) describe the extent of current use of OFC in patients with depressive disorders, and (2) compare health care utilization patterns and medical costs of patients receiving fluoxetine therapy before and after the initiation of olanzapine treatment. Data source consisted of medical, pharmaceutical, and disability claims from a Fortune 100 manufacturer from 1996 to 1998 (N>100,000). The sample included individuals with medical or disability claims for major depressive disorders treated with OFC (nOFC=36). Resource utilization and costs were compared for fluoxetine patients before and after the initiation of olanzapine treatment. Eleven percent of patients on combination therapy received olanzapine and fluoxetine. For patients on fluoxetine, there was a statistically significant reduction in health care utilization, and overall medical costs (20%), following initiation of olanzapine therapy. Overall, it appears the addition of olanzapine to ongoing fluoxetine therapy is effective in reducing outpatient, office, and inpatient utilization, as well as medical costs of patients treated for depression. Further research is needed to investigate combination therapy more fully. Psychopharmacology Bulletin. 2003;37(3):90-98

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14608242&dopt=Abstract fluoxetine




Biochem Pharmacol. 2003 Dec 1;66(11):2125-32.
Mechanism of block by fluoxetine of 5-hydroxytryptamine3 (5-HT3)-mediated currents in NCB-20 neuroblastoma cells.

Choi JS, Choi BH, Ahn HS, Kim MJ, Rhie DJ, Yoon SH, Min do S, Jo YH, Kim MS, Sung KW, Hahn SJ.

Department of Physiology, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, South Korea.

The effect of fluoxetine (Prozac) on 5-hydroxytryptamine(3) (5-HT(3))-mediated currents in NCB-20 neuroblastoma cells was examined using the whole-cell patch-clamp technique. Fluoxetine produced a significant reduction of peak amplitude without altering the activation time course of 5-HT(3)-mediated currents. These effects were concentration-dependent, with an IC(50) value of 4.15 microM. No voltage dependence was evident in fluoxetine's block of 5-HT(3)-mediated currents over the entire voltage range tested. The extent of block by pre-application of fluoxetine was significantly greater than that by co-application. Fluoxetine also increased the apparent rate of current desensitization to 5-HT application. Using a first-order kinetics analysis, the open-channel blocking rate constants were 0.06 microM(-1)s(-1) (k(+1), association rate constant) and 0.05 s(-1) (k(-1), dissociation rate constant), with an apparent K(d) (=k(-1)/k(+1)) of 0.83 microM. This value is close to an IC(50) of 1.11 microM obtained from the reduction in tau, the time constant of desensitization. Intracellular application of fluoxetine for long durations had no effect on the amplitude or kinetics of 5-HT(3)-mediated currents. Similarly, norfluoxetine, the major metabolite of fluoxetine, reduced the peak current, and enhanced the rate of current desensitization in a concentration-dependent manner with an IC(50) of 2.66 microM, indicating that norfluoxetine is more potent than fluoxetine in blocking 5-HT(3)-mediated currents. These results indicate that, at clinically relevant concentrations, fluoxetine and its metabolite, norfluoxetine, block 5-




Int J Mol Med. 2003 Apr;11(4):535-42.
Differential effects of fluoxetine enantiomers in mammalian neural and cardiac tissues.

Magyar J, Rusznak Z, Harasztosi C, Kortvely A, Pacher P, Banyasz T, Pankucsi C, Kovacs L, Szucs G, Nanasi PP, Kecskemeti V.

Department of Physiology, University of Debrecen, Medical School, H-4012 Debrecen, Hungary.

Racemic fluoxetine is a widely used SSRI antidepressant compound having also anticonvulsant effect. In addition, it was shown that it blocked several types of voltage gated ion channels including neural and cardiac calcium channels. In the present study the effects of enantiomers of fluoxetine (R(-)-fluoxetine and S(+)-fluoxetine) were compared on neuronal and cardiac voltage-gated Ca2+ channels using the whole cell configuration of patch clamp techniques, and the anticonvulsant action of these enantiomers was also evaluated in a mouse epilepsy model. In isolated pyramidal neurons of the dorsal cochlear nucleus of the rat the effect of fluoxetine (S(+), R(-) and racemic) was studied on the Ca2+ channels by measuring peak Ba2+ current during ramp depolarizations. All forms of fluoxetine reduced the Ba2+ current of the pyramidal cells in a concentration-dependent manner, with a Kd value of 22.3+/-3.6 microM for racemic fluoxetine. This value of Kd was higher by one order of magnitude than found in cardiac myocytes with fluoxetine enantiomers (2.4+/-0.1 and 2.8+/-0.2 microM). Difference between the effects of the two enantiomers on neuronal Ba2+ current was observed only at 5 microM concentration: R(-)-fluoxetine inhibited 28+/-3% of the peak current, while S(+)-fluoxetine reduced the current by 18+/-2% (n=13, P<0.05). In voltage clamped canine ventricular cardiomyocytes both enantiomers of fluoxetine caused a reversible concentration-dependent block of the peak Ca2+ current measured at 0 mV. Significant differences between the two enantiomers in this blocking effect was observed at low concentrations only: S(+)-fluoxetine caused a higher degree of bloc

unimo.it

RATIONALE: Impairment of sexual activity is one of the most frequent side effects of antidepressant drugs. The increase in the synaptic concentrations of serotonin seems to be mainly responsible. Mirtazapine is a novel antidepressant that increases the synaptic concentrations of both noradrenaline and serotonin; moreover, it is an antagonist at 5-HT(2C) receptors, whose activation is considered to be responsible for some typical effects of serotonin on the ejaculation process (retardation of ejaculation, anorgasmia). OBJECTIVES: To study the influence of mirtazapine on copulatory performance and sexual motivation in male rats, in comparison-or in combination-with fluoxetine. METHODS: Copulatory performance was studied either in sexually experienced or in sexually naive rats; sexual motivation was studied in sexually experienced rats. Mirtazapine (1, 5 or 10 mg/kg), fluoxetine (10 mg/kg), and the combination of mirtazapine + fluoxetine (10+10 mg/kg) were subcutaneously (s.c.) administered either acutely or daily for 13 days. RESULTS: After acute administration, mirtazapine decreased mount latency (ML) and intromission latency (IL), and increased mount frequency (MF) and ejaculation latency (EL). Fluoxetine had no significant effect on any of the sexual behavior parameters. After a 13-day treatment, mirtazapine increased ML, IL and MF; fluoxetine increased ML, IL and the intercopulatory interval (ICI); the addition of mirtazapine to fluoxetine produced a reduction of ICI and an increase of MF. Moreover, mirtazapine significantly improved the performance of rats in the sexual motivation test. CONCLUSIONS: The present results show that, on the whole, the acute administration of mirtazapi

centras.lt

The problem of acute intoxication has become very urgent now due to a great number of various chemical preparations accumulated during the last decades in the environment. Intoxications with psychotropic drugs and their mixtures form the significant part of the intoxications; there is an increasing tendency of intoxication with several preparations at a time. Amitriptyline and codeine are the preparations, which more frequently can cause intoxication. Fluoxetine is one of the newest and often used antidepressants. Under certain circumstances, like overdose, using all preparations together, long term using or using for suicide, these preparations can be even a cause of death. In such cases amitriptyline, fluoxetine and codeine become the objects of chemical-toxicological analysis. The possibility of the separation and identification of amitriptyline, fluoxetine and codeine in the mixture using thin-layer chromatography was established. Dragendorf reagent, modified by Munje, is most suitable for the spray-distinct of the chromatographic plates for all three substances. Amitriptyline research limit, using this developer, is 0.4 micro g, fluoxetine - 1.6 micro g, codeine - 0.8 micro g. Most acceptable for separation the components of the mixture are 5 mobile phases: 1. Diethyl acetate-methanol-ammonium hydroxide (concentrated solution) (85:10:5). Amitriptyline, fluoxetine and codeine R(f) medium values respectively are 0.94; 0.63; 0.51. 2. Buthylacetate-methanol-ammonium hydroxide (concentrated solution) (85:10:5). Amitriptyline, fluoxetine and codeine R(f) medium values respectively are 0.65; 0.24; 0.1

centras.lt

The objective of this research - to develop the methodics for analysis of amitriptyline, fluoxetine and codeine in the mixture. RESULTS. The analytical method of amitriptyline, codeine and fluoxetine in the mixture identification and quantitative determination using ultraviolet spectrophotometry was established. Preparations in the mixture can't be separated, because material ultraviolet light peaks are in insufficient distance and therefore cover one another. The maximum of ultraviolet light absorption for amitriptyline is at 217-220 and 238-240 nm; fluoxetine - at 226-228 nm; codeine - at 224-248 and 284-286 nm. Using ultraviolet spectroscopy it's possible to identify amitriptyline, fluoxetine and codeine only after separating mixture components by thin-layer chromatography, the same time executing cleaning of extracts from blood and urine. Using ultraviolet spectroscopy can be identificated at least 0.5 micro g/ml amitriptyline, 1.5 micro g/ml fluoxetine and 1.0 micro g/ml codeine. The intervals of the quantitative determination: 5-25 micro g/ml amitriptyline; 5-30 micro g/ml fluoxetine; 100-300 micro g/ml codeine; relative error of the measurement, when confidence level is 95%, is from 0.66 to 1.2% for amitriptyline; from 0.66 to 1.45% for fluoxetine; from 0.33 to 0.88% for codeine. Standard deviation is from 1.15 to 2.08% for amitriptyline; from 1.15 to 2.52% for fluoxetine; from 0.57 to 1.53% for codeine. Molar absorption coefficients for all three preparations in distillated water were determinated. Conclusions: recommended methodology suits for mixture, extracted from biological liquids, components separation,