Amlodipine chemical structure
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Amlodipine Chemical Structure: Core Features and Functional Groups
Amlodipine is a synthetic dihydropyridine calcium channel blocker, and its chemical structure is central to its pharmacological activity. The structure of amlodipine maleate is described as 2-[(2-Aminoethoxy)methyl]-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-3,5-pyridinedicarboxylic acid 3-ethyl 5-methyl ester (Z)-2-butenedioate. This means the molecule contains a 1,4-dihydropyridine ring, which is substituted with a 2-chlorophenyl group, a methyl group, and two carboxylic acid esters (one ethyl and one methyl ester). Additionally, it has a side chain with an aminoethoxy group, which is important for its activity and solubility .
Stereochemistry and Enantiomers of Amlodipine
Amlodipine exists as a racemic mixture, but only the (-)-S enantiomer is pharmacologically active. The absolute configuration of the active enantiomer was determined to be S, correcting earlier reports that suggested an R configuration. This S configuration is consistent with other active 1,4-dihydropyridines and is crucial for its calcium channel blocking activity 25.
Structural Analysis Techniques
The chemical structure of amlodipine and its salts has been confirmed using several analytical techniques, including high-performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), elemental analysis, and X-ray powder diffraction (XRD). These methods provide a comprehensive understanding of the molecule’s structure and purity 15.
Planarity and Membrane Interactions
Crystallographic studies show that the dihydropyridine ring in amlodipine is more planar compared to similar drugs like nimodipine. The molecule also has a significant torsion angle between the dihydropyridine and aryl rings. The protonated amino group extends away from the core ring, which allows for both ionic and hydrophobic interactions with cell membranes. These structural features contribute to amlodipine’s unique pharmacokinetic and pharmacodynamic properties, such as its long duration of action 47.
Photostability and Degradation
Amlodipine is sensitive to light, and exposure to ultraviolet (UV) or sunlight can lead to the formation of a dehydrogenated photoproduct. This photodegradation primarily affects the dihydropyridine ring, altering the chemical structure and potentially reducing the drug’s effectiveness .
Thermodynamic Properties and Structure-Property Relationship
The physical properties of amlodipine, such as melting and boiling points, are closely related to its chemical structure. Group contribution methods, like the Joback method, have been used to estimate these properties, confirming the accuracy of the structural breakdown and supporting its use in industrial applications .
Conclusion
Amlodipine’s chemical structure is defined by a substituted 1,4-dihydropyridine ring with specific functional groups and stereochemistry that are essential for its activity as a calcium channel blocker. The S enantiomer is the active form, and the molecule’s planarity and side chains influence its interaction with biological membranes and its pharmacological profile. Analytical and computational studies confirm the structure and provide insights into its stability and physical properties, all of which are important for its clinical use and pharmaceutical development 1245+3 MORE.
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