citalopram escitalopram Lexapro
Liquid chromatography--electrospray ionisation mass spectrometry method for the determination of escitalopram in human plasma and its application in bioequivalence study.

Singh SS, Shah H, Gupta S, Jain M, Sharma K, Thakkar P, Shah R.

Biomedical and DMPK Department, Zydus Research Centre, Sarkhej-Bavla N.H. No. 8A, Moraiya, Ahmedabad 382213, India. sonusingh zyduscadila.com

A novel liquid chromatographic--electrospray ionisation mass spectrometric (LC--ESI-MS) method has been developed for the determination of escitalopram, an antidepressant in human plasma using paroxetine as internal standard. The method involved liquid--liquid extraction of the analyte from human plasma with a mixture of diethyl ether and dichloromethane (70:30, v/v). The chromatographic separation was achieved within 7.0 min by using 2.0 mM ammonium acetate (pH 5.0)--acetonitrile (54:46, v/v) as mobile phase and a ODS YMCAQ 150 mm x 4.6 mm analytical column; the flow-rate was 1.0 ml/min. Ion signals m/z 325.0 and 330.0 for escitalopram and internal standard, were measured in the positive mode. A detailed validation of the method was performed as per USFDA guidelines and the standard curves were found to be linear in the range of 1.0-200 ng/ml with a mean correlation coefficient more than 0.99. The absolute recovery was more than 75% for both escitalopram and internal standard. The method was simple, sensitive, precise, accurate and was successfully applied to the bioequivalence study of escitalopram in healthy, male, human subjects.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15522722&dopt=Abstract citalopram escitalopram Lexapro



citalopram escitalopram Lexapro
Efficacy and tolerability of venlafaxine in geriatric outpatients with major depression: a double-blind, randomised 6-month comparative trial with citalopram.

Allard P, Gram L, Timdahl K, Behnke K, Hanson M, Sogaard J.

Department of Clinical Sciences, Division of Psychiatry, Umea University, Umea, Sweden. per.allard psychiat.umu.se

BACKGROUND: The objectives of the study were to compare efficacy and tolerability of venlafaxine ER 75-150 mg/day with that of citalopram 10-20 mg/day in elderly patients with major depression according to DSM-IV criteria. METHODS: A randomised, double-blind, parallel group 6-month study. Efficacy was assessed by MADRS, CGI Global Improvement, CGI Severity of Illness and GDS-20 scores and safety by physical examinations, vital signs, adverse events and UKU side effect rating. Plasma levels of venlafaxine, its major metabolite O-desmethylvenlafaxine and citalopram were followed. RESULTS: One hundred and fifty-one male and female patients (64-89 years) were enrolled and 118 patients completed the study. Comparable improvements in MADRS, CGI Severity of Illness, CGI Global Improvement and GDS-20 were observed during venlafaxine and citalopram treatment. The MADRS remission rate was 19% for venlafaxine and 23% for citalopram. Side effects were common during both treatments but differed in tremor being more common during citalopram and nausea/vomiting during venlafaxine treatment. There were no clinically significant changes in blood pressure or body weight. CONCLUSION: The observed benefits of venlafaxine treatment in elderly patients with major depression were similar to those observed in younger adults as were reported adverse events and side effects. Treatment with venlafaxine ER was well tolerated and induced beneficial effects of similar magnitude as those of citalopram. Copyright (c) 2004 John Wiley & Sons, Ltd.

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citalopram escitalopram Lexapro
Postmortem redistribution of the enantiomers of citalopram and its metabolites: an experimental study in rats.

Kugelberg FC, Druid H, Carlsson B, Ahlner J, Bengtsson F.

Division of Clinical Pharmacology, Department of Medicine and Care, Faculty of Health Sciences, Linkoping University, SE-581 85 Linkoping, Sweden. fredrik.kugelberg imv.liu.se

A rat model was used to study if postmortem redistribution of the S- and R-enantiomers of citalopram (CIT) and its metabolites demethylcitalopram (DCIT) and didemethylcitalopram (DDCIT) occurs after three different subcutaneous dosing procedures with racemic CIT. Two groups underwent chronic administration (20 mg/kg daily) using osmotic pumps. After 10 days, 1 of these groups received an acute-on-chronic drug challenge with a single injection of 100 mg/kg. The third group received the single 100 mg/kg dose only. Heart blood and brain samples were collected antemortem and 1, 3, or 24 h postmortem for enantioselective HPLC analysis. Increased postmortem blood drug and metabolite concentrations compared with corresponding antemortem concentrations were observed in all groups (p < 0.05 to p < 0.001). At 24 h after death, the ratios between postmortem and antemortem blood concentrations were around 3-4 for CIT as well as for the metabolites. In the brain, no major differences between antemortem and postmortem drug and metabolite concentrations were observed. The enantiomeric (S/R) concentrations ratios of CIT and metabolites in blood and brain were of similar magnitude before and after death. No differences between antemortem and postmortem parent drug-to-metabolite (P/M) ratios for CIT/DCIT in blood were observed. Finally, this animal model demonstrates that the S- and R-enantiomers of CIT and its metabolites were redistributed to the same extent postmortem.

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citalopram escitalopram Lexapro
Citalopram inhibits L-type calcium channel current in rat cardiomyocytes in culture.

Hamplova-Peichlova J, Krusek J, Paclt I, Slavicek J, Lisa V, Vyskocil F.

Psychiatric Clinic, First Medical Faculty, Charles University, Prague, Czech Republic.

Selective serotonine reuptake inhibitors (SSRI) are believed to be less dangerous in the treatment of depressive disorder in comparison with tricyclic antidepressants (TCA) due to their relative lack of cardiotoxicity. Thus, we investigated the effect of citalopram (SSRI) on membrane electrophysiology in rat cardiomyocytes in tissue culture. The results were compared with those from amitriptyline (TCA). The whole-cell configuration patch-clamp technique was used. Both citalopram and amitriptyline exhibited the concentration-dependent inhibition of the L-type calcium channel current (ICa). Citalopram in concentrations of 3 microM and 10 microM inhibited peak calcium current by 2.7% and 8%, respectively. We demonstrated the same potency of citalopram and amitriptyline to inhibit ICa. These observations led us to conclude that citalopram and amitriptyline are drugs, which exhibit a similar potency for causing concentration-dependent inhibition of ICa.

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citalopram escitalopram Lexapro
Utility of sparse concentration sampling for citalopram in elderly clinical trial subjects.

Bies RR, Feng Y, Lotrich FE, Kirshner MA, Roose S, Kupfer DJ, Pollock BG.

Department of Psychiatry and Pharmaceutical Sciences, University of Pittsburgh, 805 Salk Hall, 3501 Terrace Street, Pittsburgh, PA 15213, USA.

The objective of this study was to evaluate whether the disposition of the selective serotonin reuptake inhibitor, citalopram, could be robustly captured using 1 to 2 concentration samples per subject in 106 patients participating in 2 clinical trials. Nonlinear mixed-effects modeling was used to evaluate the pharmacokinetic parameters describing citalopram's disposition. Both a prior established 2-compartment model and a de novo 1-compartment pharmacokinetic model were used. Covariates assessed were concomitant medications, race, sex, age (22-93 years), and weight. Covariates affecting disposition were assessed separately and then combined in a stepwise manner. Pharmacokinetic characteristics of citalopram were well captured using this sparse sampling design. Two covariates (age and weight) had a significant effect on the clearance and volume of distribution in both the 1- and 2-compartment pharmacokinetic models. Clearance decreased 0.23 L/h for every year of age and increased 0.14 L/h per kilogram body weight. It was concluded that hyper-sparse sampling designs are adequate to support population pharmacokinetic analysis in clinically treated populations. This is particularly valuable for populations such as the elderly, who are not typically available for pharmacokinetic studies.

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citalopram escitalopram Lexapro
Anticonvulsant action of GBR-12909 and citalopram against acute experimentally induced limbic seizures.

Clinckers R, Smolders I, Meurs A, Ebinger G, Michotte Y.

Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium.

We recently showed that intrahippocampally administered dopamine and serotonin exert concentration-dependent non-protective, protective and proconvulsant effects against limbic seizures in rats. Anticonvulsant action was mediated via, respectively, hippocampal D2 and 5-HT1A receptor stimulation, while proconvulsant effects were associated with concomitant hippocampal glutamate increases. We here examined whether increases in endogenous hippocampal dopamine and serotonin exert similar actions. Initially, dose-response experiments were performed with intrahippocampal perfusions of GBR-12909 and citalopram, respectively, selective dopamine and serotonin re-uptake blockers. Based on their effects on monoaminergic release, a potential non-protective, protective and proconvulsant concentration was selected. The predicted non-protective GBR-12909 (10 microM) and citalopram (0.5 microM) concentrations failed to prevent pilocarpine-induced seizures. The predicted protective GBR-12909 (100 microM) and citalopram (1 microM) perfusions resulted in complete anticonvulsant action, again mediated by D2 and 5-HT1A receptors. Unexpectedly, at predicted proconvulsant concentrations complete anticonvulsant action was obtained and hippocampal Glu remained unaltered. This study shows that selective monoamine re-uptake blockers have important anticonvulsant properties. Based on the previously established anticonvulsant monoamine ranges, anticonvulsant threshold concentrations can be predicted for compounds with endogenous dopamine or serotonin promoting effects. Non-selective actions curtailing glutamatergic activity may further be responsible for the unexpected anticonvulsant effects at predicted proconvulsant concentrations.

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citalopram escitalopram Lexapro
Characterization of an allosteric citalopram-binding site at the serotonin transporter.

Chen F, Larsen MB, Neubauer HA, Sanchez C, Plenge P, Wiborg O.

Laboratory of Molecular Neurobiology, Department of Biological Psychiatry, Aarhus Psychiatric University Hospital, Risskov, Denmark.

The serotonin transporter (SERT), which belongs to a family of sodium/chloride-dependent transporters, is the major pharmacological target in the treatment of several clinical disorders, including depression and anxiety. In the present study we show that the dissociation rate, of [3H]S-citalopram from human SERT, is retarded by the presence of serotonin, as well as by several antidepressants, when present in the dissociation buffer. Dissociation of [3H]S-citalopram from SERT is most potently inhibited by S-citalopram followed by R-citalopram, sertraline, serotonin and paroxetine. EC50 values for S- and R-citalopram are 3.6 +/- 0.4 microm and 19.4 +/- 2.3 microm, respectively. Fluoxetine, venlafaxine and duloxetine have no significant effect on the dissociation of [3H]S-citalopram. Allosteric modulation of dissociation is independent of temperature, or the presence of Na+ in the dissociation buffer. Dissociation of [3H]S-citalopram from a complex with the SERT double-mutant, N208Q/N217Q, which has been suggested to be unable to self-assemble into oligomeric complexes, is retarded to an extent similar to that found with the wild-type, raising the possibility that the allosteric mechanism is mediated within a single subunit. A species-scanning mutagenesis study comparing human and bovine SERT revealed that Met180, Tyr495 and Ser513 are important residues in mediating the allosteric effect, as well as contributing to high-affinity binding at the primary site.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15606893&dopt=Abstract citalopram escitalopram Lexapro