Faculty Publications
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Item Cocrystals of Ethenzamide: Study of Structural and Physicochemical Properties(American Chemical Society service@acs.org, 2016) Hariprasad, V.M.; Nechipadappu, S.K.; Trivedi, D.R.Pharmaceutical cocrystals of an analgesic drug ethenzamide (ETZ) with various coformers, namely, gallic acid (GA), 2-nitrobenzoic acid (2NB), 3-nitrobenzoic acid (3NB), 2,4-dinitrobenzoic acid (DNB), and 3-toluic acid (3TA) were synthesized by the solvent evaporation method. All the cocrystals were characterized by various analytical techniques, and the crystal structures were determined by the single-crystal X-ray diffraction method (SCXRD). SCXRD analysis revealed that all the synthesized cocrystals were formed through a robust supramolecular acid-amide heterosynthon except the ethenzamide/gallic acid cocrystal, where molecules interacted through O-H···O hydrogen bond involving -OH of gallic acid and oxygen of amide group of the ETZ molecule. The physicochemical properties such as stability, hygroscopicity, and solubility studies of the ETZ-GA cocrystal were evaluated. It was found that the ETZ-GA cocrystal has a higher solubility (2-fold) than that of the pure ETZ drug molecule. Hygroscopic study of the ETZ-GA cocrystal revealed that synthesized cocrystal was non-hygroscopic at ?75% RH conditions. The ETZ-GA cocrystal found to be stable for a time period of four months at ambient temperature. © 2016 American Chemical Society.Item Structural and physicochemical characterization of pyridine derivative salts of anti-inflammatory drugs(Elsevier B.V., 2017) Nechipadappu, S.K.; Trivedi, D.R.Salts of common anti-inflammatory drugs mefenamic acid (MFA), tolfenamic acid (TFA) and naproxen (NPX) with various pyridine derivatives (4-amino pyridine (4AP), 4-dimethylaminopyridine (DMAP) and 2-amino pyridine (2AP)) were synthesized by crystal engineering approach based on the pKa values of API's and the salt former. All the salts were characterized systematically by various spectroscopic methods including FT-IR and 1H NMR and the crystal structure was determined by single-crystal X-ray diffraction techniques (SCXRD). DMAP salt of NPX and 2AP salts of MFA and TFA were not obtained in the salt screening experiments. All the molecular salts exhibited 1:1 molecular stoichiometry in the asymmetric unit and except NPX-2AP salt, all the molecular salts included a water molecule in the crystal lattice. Physicochemical and structural properties between drug-drug molecular salts of MFA-4AP, TFA-4AP and NPX-4AP have been evaluated and it was found that these molecular salts were found to be stable for a time period of six months at ambient condition and further hydration of molecular salts were not observed even at accelerated humid conditions (?75% RH). It was found that 4AP salts of MFA and TFA and DMAP salts of MFA and TFA are isostructural. © 2017 Elsevier B.V.Item Cocrystal of nutraceutical sinapic acid with Active Pharmaceutical Ingredients ethenzamide and 2-chloro-4-Nitrobenzoic acid: Equilibrium solubility and stability study(Elsevier B.V., 2018) Nechipadappu, S.K.; Trivedi, D.R.Sinapic acid (SNP) is a nutraceutical compound of hydroxybenzoic acid derivative which possesses anti-oxidant, anti-microbial, anti-inflammatory, anti-cancer, and anti-anxiety activity properties. In the present work, two cocrystals of SNP with two active drug ingredients such as Ethenzamide (ETZ) and 2-chloro-4-nitrobenzoic acid (CNB) are reported. Both the cocrystals were synthesized via simple solvent evaporation method and the crystal structures were characterized by Single Crystal X-ray Diffraction (SC-XRD) techniques. The cocrystals were formed via robust acid-amide heterosynthon and acid-acid homosynthon between SNP and drug molecules. Both the cocrystals were crystallized in monoclinic crystal system with P 21/c space group. The synthesized cocrystals were further characterized by DSC, PXRD, FT-IR, and 1H NMR techniques. The solubility study in purified distilled water and in 0.1 N HCl solution demonstrate that there was no increment in the solubility of drug molecules in the cocrystals in both purified water and in 0.1 N HCl solution. The synthesized cocrystal exhibited six months stability at ambient conditions (?25 °C, 60–65% RH). © 2018 Elsevier B.V.