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Ranjit Thakuria

Bio: Ranjit Thakuria is an academic researcher from Gauhati University. The author has contributed to research in topics: Cocrystal & Chemistry. The author has an hindex of 19, co-authored 48 publications receiving 1537 citations. Previous affiliations of Ranjit Thakuria include University of Hyderabad & Tel Aviv University.


Papers
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Journal ArticleDOI
TL;DR: In this review the success of numerous pharmaceutical cocrystals for the improvement of the solubility and dissolution rates of poorly soluble drugs is demonstrated using various examples taken from the literature.

499 citations

Journal ArticleDOI
TL;DR: In this paper, the updated concepts on the nature of π-π interactions and their use in various fields ranging from crystal engineering to materials science to biochemistry are discussed and discussed.
Abstract: The updated concepts on the nature of π–π interactions and their use in various fields ranging from crystal engineering to materials science to biochemistry are discussed. This is the opening paper...

188 citations

Journal ArticleDOI
TL;DR: In this paper, two polymorphs of the well-known diuretic drug Lasix, generic name furosemide, are characterized by single crystal X-ray diffraction to give a trimorphic cluster of polymorphs: known form 1 in P1 space group, and novel forms 2 and 3 in P21/n and P 1 space groups.
Abstract: Two polymorphs of the well-known diuretic drug Lasix, generic name furosemide, are characterized by single crystal X-ray diffraction to give a trimorphic cluster of polymorphs: known form 1 in P1 space group, and novel forms 2 and 3 in P21/n and P1 space groups. The conformationally flexible molecule 4-chloro-2-[(2-furanylmethyl)amino]-5-sulfamoylbenzoic acid has variable torsions at the sulfonamide and furyl ring portions in conformers which lie in a 6 kcal mol−1 energy window. A conformer surface map was calculated to show that the two conformations in crystal form 1 are ∼4.5 kcal mol−1 less stable than conformers present in forms 2 and 3 (0.7, 0.0 kcal mol−1). The stabilization of molecular conformations is analyzed in terms of attractive intramolecular N−H···Cl hydrogen bonds and minimization of repulsive S═O···Cl interactions. Phase stability relationships confirm the thermodynamic nature of form 1 in grinding and slurry experiments by X-ray powder diffraction and infrared spectroscopy. Despite the...

126 citations

Journal ArticleDOI
18 Feb 2018
TL;DR: Case studies preferably the reported drug‑drug, drug‑nutraceutical cocrystals, and a few salts are discussed with an emphasis on their role in physicochemical property modulation.
Abstract: The pre-formulation of pharmaceutical cocrystals and salts is a concept of crystal engineering that has emerged as a promising technique for drug development in pharmaceutical industry. Recent introduction of pharmaceutical cocrystals in regulatory guidelines of US Food and Drug Administration (FDA) made them one of the potential alternatives when salt preparation is not feasible. Apart from generally regarded as safe (GRAS) coformers, drug‑drug and drug‑nutraceutical cocrystals are recent additions to pharmaceutical cocrystal family that have additional health benefits. Indeed, preparation of salt forms is a routine practice to deal with inadequacies associated with the active pharmaceutical ingredient (API) and happens to be a potentially reliable method. Amongst them, drug-drug and drug-nutraceutical cocrystals have drawn significant importance in the recent past as they reduce drug load and cost effects during multiple disease diagnosis. However, one has to be prudent in the selection of drug molecules, the presence of complementary hydrogen bond synthon, disease management during multiple disease therapy, etc. that play important roles in their preparation. That is the reason why drug–drug cocrystals are scarce in the literature compared to pharmaceutical cocrystals containing GRAS coformers and salt forms. Herein, we discuss case studies preferably the reported drug‑drug, drug‑nutraceutical cocrystals, and a few salts with an emphasis on their role in physicochemical property modulation.

107 citations

Journal ArticleDOI
TL;DR: The stability of four polymorphs of pyrazinamide, α, β, γ, and δ, was studied under solvent-mediated crystallization, neat and liquid-assisted grinding, polymorph seeding, and ambient storage conditions.
Abstract: The stability of four polymorphs of pyrazinamide, α, β, γ, and δ, was studied under solvent-mediated crystallization, neat and liquid-assisted grinding, polymorph seeding, and ambient storage conditions. In contrast to a recent report that the δ polymorph is the most stable modification (Castro et al. Cryst. Growth Des. 2010, 10, 274), we find that the α polymorph is the thermodynamic form. β, γ, and δ transform to the α phase in the above-mentioned conditions as monitored by infrared, near-infrared, and Raman spectroscopy, differential scanning calorimetry, and X-ray powder diffraction. Transformation to the high temperature γ phase is monitored by thermogravimetric analysis-infrared (TG-IR) spectrometry. A semischematic energy−temperature diagram consistent with phase transformation experiments, thermal measurements, and crystal structure data gives the order α < δ < γ < β at 25 °C (α is the most stable form), whereas at 160 °C γ < α < δ < β (γ stable modification), but at absolute zero δ < α < β < γ (δ...

94 citations


Cited by
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01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

1,652 citations

Journal ArticleDOI
TL;DR: A review of the recent advances in the field of insoluble drug delivery and business prospects covers the development of drug candidates with greater lipophilicity, high molecular weight and poor water solubility.

885 citations

Journal ArticleDOI
TL;DR: In this article, the authors reviewed several novel examples of pharmaceutical cocrystals from the past decade and analyzed the enhanced solubility profiles of cocrystal profiles, showing that the peak dissolution for pharmaceutical cocystals occurs in a short time (<30 min), and high-solubility is maintained over a sufficiently long period (4-6 h) for the best cases.
Abstract: The current phase of drug development is witnessing an oncoming crisis due to the combined effects of increasing R&D costs, decreasing number of new drug molecules being launched, several blockbuster drugs falling off the patent cliff, and a high proportion of advanced drug candidates exhibiting poor aqueous solubility. The traditional approach of salt formulation to improve drug solubility is unsuccessful with molecules that lack ionizable functional groups, have sensitive moieties that are prone to decomposition/racemization, and/or are not sufficiently acidic/basic to enable salt formation. Several novel examples of pharmaceutical cocrystals from the past decade are reviewed, and the enhanced solubility profiles of cocrystals are analyzed. The peak dissolution for pharmaceutical cocrystals occurs in a short time (<30 min), and high solubility is maintained over a sufficiently long period (4–6 h) for the best cases. The enhanced solubility of drug cocrystals is similar to the supersaturation phenomenon ...

818 citations

Journal ArticleDOI
TL;DR: The 10th edition of CrystEngComm as mentioned in this paper highlighted the state-of-the-art of crystal engineering and new trends and developing areas in crystal engineering, such as intermolecular interactions, metal-organic frameworks or coordination polymers; polymorphism and solvates.
Abstract: The articles published in the tenth anniversary issue of CrystEngComm are reviewed. The issue highlighted the state-of-the-art of crystal engineering and new trends and developing areas in crystal engineering. In particular, the following article emphasises developments in the areas of intermolecular interactions, notably hydrogen and halogen bonds; metal–organic frameworks or coordination polymers; polymorphism and solvates.

674 citations