Amlodipine Besylate
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C20H25ClN2O5·C6H6O3S 567.05

3,5-Pyridinedicarboxylic acid, 2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-, 3-ethyl 5-methyl ester, (±)-, monobenzenesulfonate.
3-Ethyl 5-methyl (±)-2-[(2-aminoethoxy)methyl]-4-(o-chlorophenyl)-1,4-dihydro-6-methyl-3,5-pyridinedicarboxylate, monobenzenesulfonate [111470-99-6].
» Amlodipine Besylate contains not less than 97.0 percent and not more than 102.0 percent of C20H25ClN2O5·C6H6O3S, calculated on the anhydrous basis.
Packaging and storage— Preserve in tight containers, protected from light. Store at room temperature.
Identification—
B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.
Optical rotation 781A: between -0.10 and +0.10, measured at 20.
Test solution: 10 mg per mL, in methanol.
Water, Method I 921: not more than 0.5%.
Residue on ignition 281: not more than 0.2%.
Related compounds—
test 1—
Adsorbent: 0.25-mm layer of chromatographic silica gel mixture.
Test solution— Transfer 140 mg of Amlodipine Besylate to a 2-mL volumetric flask, dissolve in and dilute with methanol to volume, and mix.
System suitability solution— Transfer about 14 mg of USP Amlodipine Besylate RS to a suitable container, dissolve in 0.2 mL of methanol, and mix.
Standard stock solution— Dissolve an accurately weighed quantity of USP Amlodipine Besylate RS in methanol to obtain a solution containing 7.0 mg per mL.
Standard solution 1— Transfer 3.0 mL of the Standard stock solution to a 100-mL volumetric flask, dilute with methanol to volume, and mix.
Standard solution 2— Transfer 1.0 mL of the Standard stock solution to another 100-mL volumetric flask, dilute with methanol to volume, and mix.
Application volume: 10 µL.
Developing solvent system— Use the upper layer of a mixture of methyl isobutyl ketone, water, and glacial acetic acid (50:25:25).
Procedure— Proceed as directed for Thin-Layer Chromatography under Chromatography 621. Dry the plate for 15 minutes at 80. Examine the plate under UV light at 254 nm and 365 nm. The chromatogram from the System suitability solution shows two clearly separated minor spots with RF values of about 0.18 and 0.22. Compare the intensities of any secondary spots observed in the chromatogram of the Test solution with those of the principal spots in the chromatograms of the Standard solutions. Any spot obtained from the Test solution, except for the principal spot, is not greater in size than the spot obtained from Standard solution 1 (0.3%), and at most two spots are more intense than the spot obtained from Standard solution 2 (0.1%).
test 2—
pH 3.0 Buffer and Mobile phase— Prepare as directed in the Assay.
System suitability solution— Dissolve about 5 mg of Amlodipine Besylate in 5 mL of hydrogen peroxide, and heat at 70 for 45 minutes.
Standard solution— Dissolve an accurately weighed quantity of USP Amlodipine Besylate RS in Mobile phase to obtain a solution having a known concentration of about 0.003 mg per mL.
Test solution— Transfer about 50 mg of Amlodipine Besylate, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.
Chromatographic system (see Chromatography 621)— Prepare as directed in the Assay. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the resolution, R, between amlodipine impurity A and amlodipine is not less than 4.5. [note—For the purpose of identification, the relative retention times are about 0.2 for benzene sulfonate, 0.5 for amlodipine impurity A, and 1.0 for amlodipine. Amlodipine impurity A is 3-ethyl 5-methyl 2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-6-methylpyridine-3,5-dicarboxylate.]Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the standard deviation for replicate injections is not more than 10.0%.
Procedure— Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms for a period of time that is about 3 times the retention time of amlodipine, and measure the peak responses. Calculate the percentage of each impurity in the portion of Amlodipine Besylate taken by the formula:
100(1/F)(CS /CT)(ri / rS)
in which F is the relative response factor, which is equal to 0.5 for amlodipine impurity A and to 1.0 for other impurities; CS and CT are the concentrations, in mg per mL, of amlodipine besylate in the Standard solution and the Test solution, respectively; ri is the peak response for each impurity obtained from the Test solution; and rS is the peak response for amlodipine besylate obtained from the Standard solution: not more than 0.3% of amlodipine impurity A is found, and not more than 0.3% of total other impurities is found. Disregard any peak less than 0.03%, and disregard any peak due to benzene sulfonate.
Assay—
pH 3.0 Buffer— Dissolve 7.0 mL of triethylamine in 800 mL of water. Adjust with phosphoric acid to a pH of 3.0 ± 0.1, and dilute with water to 1 L.
Mobile phase— Prepare a filtered and degassed mixture of pH 3.0 Buffer, methanol, and acetonitrile (50:35:15). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation— Dissolve an accurately weighed quantity of USP Amlodipine Besylate RS in Mobile phase to obtain a solution having a known concentration of about 0.05 mg per mL.
Assay preparation— Transfer about 50 mg of Amlodipine Besylate, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix. Transfer 5.0 mL of this solution to a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 237-nm detector and a 3.9-mm × 15-cm column that contains packing L1. The flow rate is about 1.0 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the standard deviation for replicate injections is not more than 2.0%.
Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the percentage of C20H25ClN2O5·C6H6O3S in the portion of Amlodipine Besylate taken by the formula:
100(CS /CU)(rU / rS)
in which CS and CU are the concentrations, in mg per mL, of amlodipine besylate in the Standard preparation and the Assay preparation, respectively; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Sujatha Ramakrishna, Ph.D.
Scientist
1-301-816-8349
(MDCV05) Monograph Development-Cardiovascular
Reference Standards Lili Wang, Technical Services Scientist
1-301-816-8129
RSTech@usp.org
USP32–NF27 Page 1532
Pharmacopeial Forum: Volume No. 34(5) Page 1136
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.