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 Pharmaceutical salts of ethionamide with GRAS counter ion donors to enhance the solubility(Elsevier B.V., 2017) Nechipadappu, S.K.; Trivedi, D.R.Pharmaceutical salts of BCS class II second line anti-tuberculosis drug ethionamide (ETH) with various counter ions namely, 2-chloro-4-nitrobenzoic acid (CNB), 2,6-dihydroxybenzoic acid (2,6HBA), 2,3-dihydroxybenzoic acid (2,3HBA) and 2,4-dinitrobenzoic acid (DNB) were synthesized by crystal engineering approach. All the synthesized salts were characterized by various spectroscopic (NMR, FT-IR,), thermal (DSC & TGA) and PXRD techniques. The crystal structure of the synthesized salts was determined by single-crystal X-ray diffraction techniques. All the reported salts, except ETH-2,3HBA exhibited charge assisted acid pyridine heterosynthon. In ETH-2,3HBA hydoxyl pyridine heterosynthon is observed. In ETH-CNB salt, both ionic and neutral acid pyridine heterosynthon were observed in the asymmetric unit. ETH-DNB salt consists of both partial and complete proton transfer from DNB to ETH in the asymmetric unit. All the synthesized salts were found to be non-hygroscopic at accelerated humid condition (~ 75% RH). Solubility experiment has been performed in purified water and in 0.1 N HCl (pH = 1) solution and found that the solubility of ETH-CNB salt was about eight-fold higher soluble than ETH in purified water. The solubility of synthesized salts follows the order of ETH < ETH-2,3HBA < ETH-2,6HBA < ETH-CNB in purified water. © 2016 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.