Escitalopram Oxalate
(es'' sye tal' oh pram ox' a late).
C20H21FN2O·C2H2O4 414.43 S-(+)-5-Isobenzofurancarbonitrile, 1-[3-(dimethylamino)propyl]-1-(4-fluorophenyl)-1,3-dihydro-, oxalate; S-(+)-1-[3-(Dimethylamino)propyl]-1-(p-fluorophenyl)-5-phthalancarbonitrile oxalate [219861-08-2]. DEFINITION
Escitalopram Oxalate contains NLT 98.0% and NMT 102.0% of C20H21FN2O·C2H2O4, calculated on the anhydrous basis.
IDENTIFICATION
• B.
The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
ASSAY
• Procedure
Solution A:
3.4 g/L of monobasic potassium phosphate in water. Adjust with phosphoric acid or sodium hydroxide solution to a pH of 3.0 prior to final dilution.
Solution B:
Acetonitrile and Solution A (1:9)
Solution C:
Acetonitrile and Solution A (13:7)
Mobile phase:
See the gradient table below.
[NoteThe gradient was established on an HPLC system with a dwell volume of approximately 1.6 mL. The injection time can be adjusted relative to the start of a run to accommodate changes in dwell volume from one HPLC system to another to achieve the separation described. ]
System suitability solution:
2 µg/mL each of USP Escitalopram Oxalate RS and USP Citalopram Related Compound D RS in Solution B
Standard solution:
0.5 mg/mL of USP Escitalopram Oxalate RS in Solution B
Sample solution:
0.5 mg/mL of Escitalopram Oxalate in Solution B
Chromatographic system
Mode:
LC
Detector:
UV 237 nm
Column:
4.6-mm × 25-cm; 5-µm packing L1
Column temperature:
45
Flow rate:
See the gradient table above.
Injection size:
20 µL
System suitability
Samples:
System suitability solution and Standard solution
Suitability requirements
Resolution:
NLT 1.5 between escitalopram and citalopram related compound D, System suitability solution
Tailing factor:
0.83, Standard solution
Relative standard deviation:
NMT 2.0%, Standard solution
Analysis
Samples:
Standard solution and Sample solution
Calculate the percent of C20H21FN2O·C2H2O4 in the portion of Escitalopram Oxalate taken:
Result = (rU/rS) × (CS/CU) × 100
Acceptance criteria:
98.0102.0% on the anhydrous basis
IMPURITIES
Organic Impurities
Solution A, Solution B, Solution C, Mobile phase, System suitability solution, Standard solution, Sample solution, and Chromatographic system:
Proceed as directed in the Assay.
System suitability
Samples:
System suitability solution and Standard solution
Suitability requirements
Resolution:
NLT 1.5 between escitalopram and citalopram related compound D, System suitability solution
Tailing factor:
0.83, Standard solution
Relative standard deviation:
NMT 2.0%, Standard solution
Analysis
Sample:
Sample solution
Calculate the percentage of each impurity in the portion of Escitalopram Oxalate taken:
Result = (rU/rS) × (1/F) × 100
Acceptance criteria
Individual impurities:
See Impurity Table 1.
Total impurities:
NMT 0.5%
Impurity Table 1
SPECIFIC TESTS
• Water Determination, Method Ia 921:
NMT 1.0%
• Enantiomeric Purity
Solution A:
Dissolve 6.8 g of monobasic potassium phosphate in 250 mL of water, add 150 mL of 0.2 N sodium hydroxide, adjust with phosphoric acid or sodium hydroxide solution to a pH of 7.0, and dilute with water to 1 L.
Mobile phase:
Acetonitrile and Solution A (3:17)
System suitability solution:
125 µg/mL each of USP R-Citalopram Oxalate RS and USP Escitalopram Oxalate RS in Mobile phase
Sample solution:
125 µg/mL of Escitalopram Oxalate in Mobile phase
Chromatographic system
Mode:
LC
Detector:
UV 240 nm
Column:
4.6-mm × 15-cm; 5-µm packing L57
Column temperature:
30
Flow rate:
0.6 mL/min
Injection size:
15 µL
System suitability
Sample:
System suitability solution
Suitability requirements
Resolution:
NLT 1.3 between R-citalopram and escitalopram
Tailing factor:
0.82.5 for escitalopram
Analysis
Sample:
Sample solution
Calculate the percentage of R-citalopram oxalate in the portion of Escitalopram Oxalate taken:
Result = (rU/rS) × 100
Acceptance criteria:
NMT 3.0%
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers.
• USP Reference Standards 11
USP R-Citalopram Oxalate RS
[(R)-1-[3-(dimethylamino)propyl]-1-(p-fluorophenyl)-5-phthalancarbonitrile oxalate] C20H21FN2O·C2H2O4 414.43
Auxiliary Information
Please check for your question in the FAQs before contacting USP.
USP35NF30 Page 3094
Pharmacopeial Forum: Volume No. 36(3) Page 668
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