title: Identification and characterization of potential impurities of amlodipine maleate.
abstract: Six impurities ranging from 0.43 to 1.42% in amlodipine maleate were detected by a simple isocratic reverse-phase high performance liquid chromatography (HPLC). LC-MS was performed to identify the mass of the impurities. Based on the spectral data (IR, NMR and MS), the structures of these impurities were characterized as 3-ethyl 5-methyl 4-(2-chlorophenyl)-2-[2-(1,3-dioxo-2,3-dihydro-1H-2-isoindolyl)ethoxymethyl]-6-methyl-1,4-dihydro-3,5-pyridinedicarboxylate (impurity I); 5-ethyl 3-methyl 4-(2-chlorophenyl)-2-methyl-6-[2-(2-methylcarbamoylphenyl-carboxamido)ethoxymethyl]-1,4-dihydro-3,5-pyridinedicarboxylate (impurity II); besylate salt of 3-ethyl 5-methyl 2-(2-aminoethoxymethyl)-4-(2-chlorophenyl)-6-methyl-3,5-pyridinedicarboxylate (impurity III); dimethyl 2-(2-aminoethoxymethyl)-4-(2-chlorophenyl)-6-methyl-1,4-dihydro-3,5-pyridinecarboxylate (impurity IV); 3-ethyl 5-methyl 2-(2-aminoethoxymethyl)-4-(4-chlorophenyl)-6-methyl-1,4-dihydro-3,5-pyridinedicarboxylate (impurity V); diethyl 2-(2-aminoethoxymethyl)-4-(2-chlorophenyl)-6-methyl-1,4-dihydro-3,5-pyridinedicarboxylate (impurity VI).
authors.affiliation: Department of Analytical Research, Discovery Research, Dr. Reddy's Laboratories Ltd., Bollaram Road, Miyapur, Hyderabad 500 049, AP, India.
authors.forename: P
authors.initials: P
authors.lastname: Sudhakar
authors.forename: M
authors.initials: M
authors.lastname: Nirmala
authors.forename: J
authors.initials: J
authors.lastname: Moses Babu
authors.forename: K
authors.initials: K
authors.lastname: Vyas
authors.forename: Ganta
authors.initials: G
authors.lastname: Madhusudan Reddy
authors.forename: B
authors.initials: B
authors.lastname: Vijaya Bhaskar
authors.forename: P
authors.initials: P
authors.lastname: Pratap Reddy
authors.forename: K
authors.initials: K
authors.lastname: Mukkanti
mesh_terms: D017311:Amlodipine / Q000032:analysis*; D002121:Calcium Channel Blockers / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004340:Drug Contamination; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D002121:Calcium Channel Blockers; D017311:Amlodipine