Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
15 results
Search Results
Item Pharmaceutical cocrystals of Efavirenz: Towards the improvement of solubility, dissolution rate and stability(Elsevier Ltd, 2021) Gowda, B.H.J.; Nechipadappu, S.K.; Shankar, S.J.; Chavali, M.; Paul, K.; Ahmed, M.G.; Sanjana, A.; Shanthala, H.K.Efavirenz (EFV) is a Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTI) class of antiretroviral drug that is included in antiretroviral therapy to treat Human Immunodeficiency Virus (HIV) patients to increase the life-span by avoiding them to develop Acquired Immune Deficiency Syndrome (AIDS). One of the major drawbacks of EFV is its solubility in purified water (0.093 mg/L). In the present work, two cocrystals of EFV using tartaric acid (TAR) and adipic acid (ADP) as coformers that are Generally Recognized as Safe (GRAS) are reported. Both the EFV-TAR and EFV-ADP cocrystals were developed using slow solvent evaporation technique and further characterization of developed cocrystal structures was done by Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC) and Powder x-ray diffraction (PXRD) techniques. The SEM photomicrographs indicated that the EFV-TAR cocrystals were in needle shape with smooth surface. Its length ranged from 100 to 300 μm. The EFV-ADP cocrystals were found to be flaky needle shape with rough surface bearing irregular edges whose length ranged about 50-400 μm. The FT-IR spectra of both developed cocrystals confirmed the formation of a hydrogen bond between EFV and coformers by indicating a notable shift in -C=O functional group. The DSC and PXRD studies were further confirmed the successful development of a novel crystalline form (Cocrystal). The solubility (25 ± 0.5 °C) of EFV-TAR and EFV-ADP cocrystals were found to be 163 and 107 μg/mL respectively, whereas pure EFV showed 94 μg/mL. The dissolution rate (37 ± 0.5 °C) of EFV-TAR and EFV-ADP cocrystals in 1% sodium lauryl sulphate (SLS) solution demonstrated 1.4 and 1.2 times increment respectively, compared to the pure EFV. The developed EFV-TAR and EFV-ADP cocrystals were found to stable for 6 months in ambient conditions (25 ± 2 °C, 60 ± 5% relative humidity). © 2021 Elsevier Ltd. All rights reserved.Item Biodegradability of PMMA blends with some cellulose derivatives(2006) Bhat, D.K.; Muthu, M.S.High polymer blends of Polymethyl methacrylate (PMMA) with cellulose acetate (CA) and Cellulose acetate phthalate (CAP) of varying blend compositions have been prepared to study their biodegradation behavior and blend miscibility. Films of PMMA-CA, and PMMA-CAP blends have been prepared by solution casting using Acetone and Dimethyl formamide(DMF) as solvents respectively. Biodegradability of these blends has been studied by four different methods namely, soil burial test, enzymatic degradation, and degradation in phosphate buffer and activated sludge degradation followed by water absorption tests to support the degradation studies. Degradation analysis was done by weight loss method. The results of all the tests showed sufficient biodegradability of these blends. Degradability increased with the increase in CA and CAP content in the blend compositions. The miscibility of PMMA-CA and PMMA-CAP blends have been studied by solution viscometric and ultrasonic methods. The results obtained reveal that PMMA forms miscible blends with either CA or CAP in the entire composition range. Miscibility of the blends may be due to the formation of hydrogen bond between the carbonyl group of PMMA and the free hydroxyl group of CA and CAP. © Springer Science+Business Media, Inc. 2006.Item Thermal degradation and swelling of thermoplastic vulcanizates from NBR/SAN and NBR/Scrap computer plastics blends(Huthig GmbH, 2009) Anandhan, S.; Rajeev, R.S.; De, S.K.; Bhowmick, A.K.Thermoplastic elastomeric blends of nitrile rubber (NBR)/poly(styrene- coacrylonitrile) (SAN) and NBR/scrap computer plastics (SCP) based on acrylonitrile-butadiene-styrene terpolymer (ABS) were prepared. Thermoplastic elastomeric blends of NBR/SAN containing various amounts of a model waste nitrile rubber powder (w-NBR) were also prepared. Thermogravimetric analysis of the above blends was performed in a nitrogen atmosphere. Both Friedman and Flynn-Wall-Ozawa methods were used for the evaluation of activation energies of thermal degradation of these blends. The dynamically vulcanised blends exhibit higher amount of activation energies for thermal degradation than the unvulcanised ones. Swelling studies were performed in various solvents having different solubility parameter values and maximum swelling was found to occur in a solvent having a solubility parameter that was closer to that of the blend components, i.e., around 20MPa1/2. Dynamically vulcan-ised blends show excellent resistance to IRM #903 oil as well as four chosen solvents possessing different solubility parameters (E).Item Miscibility studies of chitosan and starch blends in buffer solution(2012) Sudhakar, Y.N.; Holla, S.R.; Muthu, M.; Bhat, D.K.The miscibility of chitosan (CS) and starch in buffer solution (CH 3COOH and CH 3COONa) has been investigated by viscosity, density and refractive index methods at 303K, 313K, and 323K. Various interaction parameters such as polymer-polymer and blend-solvent interaction parameters and heat of mixing have been calculated using viscosity and density data. The results indicated the existence of positive interactions in the blend polymer solutions and that they are miscible below 40% of starch compositions. The study also revealed that variation of temperature does have significant effect on the miscibility of chitosan and starch blends. © 2012 Copyright Taylor and Francis Group, LLC.Item Miscibility, water uptake, ion exchange capacity, conductivity and dielectric studies of poly(methyl methacrylate) and cellulose acetate blends(2013) Jois, H.S.S.; Bhat, D.K.In the last few decades, polymer blends with good miscibility and conductivity have been the focus of study for material scientists. Here, polymer blends of Poly(methyl methacrylate) (PMMA) and Cellulose acetate (CA) of varying blend compositions have been prepared by solution casting method and their miscibility, water uptake, ion exchange capacity (IEC) proton conductivity, and dielectric properties have been studied. Dimethyl formamide (DMF) was used as solvent. Fourier transform infrared spectra (FTIR) and Differential scanning calorimetry (DSC) measurements have been used to analyze the miscibility of the blends. Up to 50/50 PMMA/CA, water uptake showed an increasing trend and for other compositions the value decreased. Ion exchange capacity and conductivity of the blends decreased with increase in PMMA content of the blends. The variations in the blend properties have been attributed to the presence of specific interactions and exchangeable groups in the blend system. The proton conductivity of the blends is in the order of 10-3 S cm-1. Impedance analysis of the blends indicated the absence of any relaxation phenomenon in the blend system. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3074-3081, 2013 Copyright © 2013 Wiley Periodicals, Inc.Item Thermodynamic miscibility and thermal and mechanical properties of poly(ethylene-co-vinyl acetate-co-carbon monoxide)/poly(vinyl chloride) blends(John Wiley and Sons Inc, 2015) SelvaKumar, M.; Mahendran, A.; Bhagabati, P.; Anandhan, S.This paper reports the miscibility and thermal and mechanical properties of solution cast binary blends of poly(ethylene-co-vinyl acetate-co-carbon monoxide) (EVACO) and poly(vinyl chloride) (PVC). The composition of these blends was varied from 10:90 to 90:10 of PVC/EVACO (w/w %). Fourier transform infrared spectroscopy revealed an extensive intermolecular attraction between the blend components, which accounts for their mutual solubility. The differential scanning calorimetry study revealed that the blend components are miscible with each other in all proportions as they exhibited a single glass transition temperature. Tensile strength, moduli, and thermal stabilities of these blends significantly improved with increasing proportion of PVC. © 2014 Wiley Periodicals, Inc.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 Reverse micellar extraction of lactoferrin from its synthetic solution using CTAB/n-heptanol system(Springer India sanjiv.goswami@springer.co.in, 2017) Pawar, S.S.; Iyyaswami, R.; Belur, P.D.The partitioning of Lactoferrin (LF) into the reverse micellar phase formed by a cationic surfactant, cetyltrimethylammonium bromide (CTAB) in n-heptanol from the synthetic solution of LF was studied. The solubilization behaviour of LF into the reverse micellar phase and back extraction using a fresh stripping phase were improved by studying the effect of processing parameters, including surfactant concentration, solution pH, electrolyte salt concentration and addition of alcohol as co-solvent. Forward extraction of 100% was achieved at CTAB concentration of 50 mM in n-heptanol solvent, pH of 10 and 1 M NaCl. The electrostatic force and hydrophobic interaction have major influence on LF extraction during forward and back extraction respectively. The size of the reverse micelles and their corresponding water content were measured at different operating conditions to assess their role on the LF extraction. The present reverse micellar system has potential to solubilise almost all the LF into the reverse micelles during forward extraction and could able to allow back extraction from the reverse micellar phase with addition of small amount of co-solvent. © 2017, Association of Food Scientists & Technologists (India).Item A Novel Enzymatic Process to Produce Oxalate Depleted Starch From Taro(Wiley-VCH Verlag info@wiley-vch.de, 2018) Kumar, K.; Belur, P.D.A novel process comprising treatment of Taro (Colocasia esculenta (L.) Schott) tuber flour with oxalate oxidase enzyme is developed to deplete the oxalate content. Oxalate oxidase enzyme produced by an endophyte, Ochrobactrum intermedium CL6 is employed to treat taro tuber flour. The treatment followed by extraction of starch results in a 97% reduction in total oxalate content. Further, several physicochemical properties such as paste clarity, swelling power, solubility, amylose content, granule size of starch produced out of enzyme treatment are studied and compared with properties of taro starch produced without enzyme treatment. The study reveals that enzyme treatment does not bring appreciable changes in the studied parameters. The taro starch produced by enzyme treatment shows very low paste clarity (9.38%), high swelling power (15.32 g/g), very low solubility (21.66%), and low amylose content (7.52%) at 100 °C compared to potato and sweet-potato starches. X-ray diffraction data reveal that taro starch possesses an A-crystalline form, unlike the B-crystalline form found in potato and sweet potato starch. To the best of the authors knowledge, for the first time, the use of oxalate oxidase to produce oxalate depleted taro starch is reported. One of the interesting food industry applications of oxalate-depleted taro starch, among many other uses could be for baby food formulation because of its small granule size. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim