Escitalopram Oxalate

Escitalopram Oxalate（Lexapro，Cipralex）is a selective inihibitor of serotonin(5-HT) reuptake (SSRI) with a Ki value of 6.6nM for [3H]-5-HT uptake [1].

Escitalopram Oxalate is the S-(+)-enantiomer of citalopram and has the inhibition of [3H]-5-HT uptake and [125I]-RTI-55 binding in COS-1 cells expressing the human serotonin transporter (5-HTT) with Ki values of 6.6±1.4nM and 3.9±2.2nM, respectively. In addition, Escitalopram Oxalate has been reported to inhibit the accumulation of 3H-labelled monoamines into rat brain synaptosomes in vitro with IC50 values of 2.1±0.75nM, 2500±202nM and 40000±15500nM for [3H]-5-HT, [3H]-I-NA and [3H]-DA, respectively. Apart from these, Escitalopram Oxalate has shown the in vitro affinity for rat histamine H1 receptors and the rat sigma σ1 site with Ki values of 1500±780nM and 100±71nM, respectively [1].

References:
[1] Sánchez C1, Bergqvist PB, Brennum LT, Gupta S, Hogg S, Larsen A, Wiborg O. Escitalopram, the S-(+)-enantiomer of citalopram, is a selective serotonin reuptake inhibitor with potent effects in animal models predictive of antidepressant and anxiolytic activities. Psychopharmacology (Berl). 2003 Jun;167(4):353-62. Epub 2003 Apr 26.

Stability-indicating RP-HPLC method for the simultaneous determination of escitalopram oxalate and clonazepam.[Pubmed:23135233]

J Chromatogr Sci. 2013 Jul;51(6):490-5.

The objective of the current study was to develop a validated, specific stability-indicating reversed-phase liquid chromatographic (LC) method for the quantitative determination of Escitalopram Oxalate and clonazepam and their related substances in bulk drugs and pharmaceutical dosage forms in the presence of degradation products. Forced degradation studies were performed on the pure drugs of Escitalopram Oxalate and clonazepam, as per the stress conditions prescribed by the International Conference on Harmonization (ICH) using acid, base, oxidation, thermal stress and photolytic degradation to show the stability-indicating power of the method. Significant degradation was observed during acid and alkaline hydrolysis and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from forced degradation studies. Good resolution between the peaks corresponded to the active pharmaceutical ingredients, Escitalopram Oxalate and clonazepam, and degradation products from the analyte were achieved on an ODS Hypersil C18 column (250 x 4.6 mm) using a mobile phase consisting of a mixture of acetonitrile-50 mM phosphate buffer + 10 mM triethylamine (70:30, v/v). The detection was conducted at 268 nm. The limit of detection and the limit of quantitation for Escitalopram Oxalate and clonazepam were established. The stress test solutions were assayed against the qualified working standards of Escitalopram Oxalate and clonazepam, which indicated that the developed LC method was stability-indicating. Validation of the developed LC method was conducted as per ICH requirements. The developed LC method was found to be suitable to check the quality of bulk samples of Escitalopram Oxalate and clonazepam.

Determination of Escitalopram Oxalate and L-Methylfolate in Tablet by Spectrophotometric and Reverse Phase High-Performance Liquid Chromatographic Methods.[Pubmed:28203815]

J Chromatogr Sci. 2017 May 1;55(5):550-555.

Two new simple and selective assay methods have been presented for the analysis of Escitalopram Oxalate (ESC) and L-Methylfolate (L-MF) in pharmaceutical formulations. The ultraviolet (UV)-Spectrophotometric simultaneous equation method was based on the measurement of absorbance at 238 nm (max of ESC) and 284 nm (max of L-MF) in methanol. The assay was linear over the concentration ranges 0.5-12.0 mug/mL for ESC and 0.5-9.0 mug/mL for L-MF. The quantitation limits for ESC and L-MF were found to be 0.912 and 0.667 mug/mL; while the detection limits were 0.301 and 0.220 mug/mL for ESC and L-MF, respectively. The second method involved isocratic reversed-phase liquid chromatography using a mobile phase composed of methanol-0.02 M phosphate buffer (pH 5.5) (75:25, v/v), Hypersil BDS-C18 Column (5 microm, 250 mm x 4.6 mm i.d.) with detection at 270 nm. The linearity ranges were found to be 3.0-30.0 and 0.75-22.5 mug/mL for ESC and L-MF, respectively. The limits of detection were found to be 1.065 and 1.160 mug/mL for ESC and L-MF, respectively. The limits of quantitation were found to be 3.226 and 3.515 mug/mL for ESC and L-MF, respectively. The proposed methods were successfully applied to the determination of commercially available tablets with a high percentage of recovery, good accuracy and precision.

Neuroprotective effect of escitalopram oxalate in rats with chronic hypoperfusion.[Pubmed:26223919]

J Huazhong Univ Sci Technolog Med Sci. 2015 Aug;35(4):514-518.

The neuroprotective effects of Escitalopram Oxalate in rats with chronic hypoperfusion and the possible mechanism were explored. Chronic hypoperfusion (2-VO) model was prepared and given Escitalopram Oxalate (experimental group) or PBS (control group) after 6 weeks. Eight weeks after the operation, Morris water maze test was carried out to evaluate the learning and memory ability of the rats. The cell proliferation, three-dimensional vascular distribution, cell morphological changes in ischemic area and the plasma vascular endothelial growth factor (VEGF) were detected to explore the possible mechanisms. (1) Morris water maze test showed that the escape latency in the experimental group was significantly shorter than in the control group, while the first quadrant swimming time in the experimental group was significantly longer than the control group (both P<0.01). (2) Cerebrovascular confocal detection results showed that the inside diameter of capillaries was significantly less in the experimental group than in the control group; the vascular density was significantly increased in the experimental group and the total area of capillaries was also significantly increased in the experimental group as compared with the control group. (3) There was statistically significant difference in BrdU-positive cells in the ischemic brain tissue between the experimental group and the control group (P=0.003<0.01). (4) VEGF concentrations in the plasma and the ischemic area were higher in the experimental group than in the control group (P<0.05). It was concluded that Escitalopram Oxalate could significantly improve the learning and memory ability of the rats with chronic cerebral ischemia probably by the VEGF-mediated angiogenesis.

Structure-activity relationships for a novel series of citalopram (1-(3-(dimethylamino)propyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbon itrile) analogues at monoamine transporters.[Pubmed:20672825]

J Med Chem. 2010 Aug 26;53(16):6112-21.

(+/-)-Citalopram (1, 1-(3-(dimethylamino)propyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carboni trile), and its eutomer, escitalopram (S-(+)-1) are selective serotonin reuptake inhibitors (SSRIs) that are used clinically to treat anxiety and depression. To further explore structure-activity relationships at the serotonin transporter (SERT), a series of (+/-)-4- and 5-substituted citalopram analogues were designed, synthesized, and evaluated for binding at the SERT, dopamine transporter (DAT) and norepinephrine transporter (NET) in native rodent tissue. Many of these analogues showed high SERT binding affinities (Ki=1-40 nM) and selectivities over both NET and DAT. Selected enantiomeric pairs of analogues were synthesized and both retained enantioselectivity as with S- and R-1, wherein S>R at the SERT. In addition, the enantiomeric pairs of 1 and 5 were tested for binding at the homologous bacterial leucine transporter (LeuT), wherein low affinities and the absence of enantioselectivity suggested distinctive binding sites for these compounds at SERT as compared to LeuT. These novel ligands will provide molecular tools to elucidate drug-protein interactions at the SERT and to relate those to behavioral actions in vivo.