Sharmistha Pal - Academia.edu (original) (raw)

Papers by Sharmistha Pal

Research paper thumbnail of Crystal structures of drugs: advances in determination, prediction and engineering

Nature Reviews Drug Discovery, 2004

Research paper thumbnail of Simultaneous Estimation Of Rifampicin And Isoniazid In Combined Dosage Forms

Indian Journal of Pharmaceutical Sciences, 2000

A simple spectrophotometric method for the simultaneous estimation of rifampicin and isoniazid in... more A simple spectrophotometric method for the simultaneous estimation of rifampicin and isoniazid in their combined pharmaceutical dosage form has been developed. The method does not require any extraction or isolation procedure. The method is simple, rapid, specific and reproducible. Recovery studies were also found to be satisfactory.

Research paper thumbnail of Mixing Effects on the Ternary Phase Diagram of Cocrystals and Gibbs Formation Energy Calculation

Research paper thumbnail of Solid State Behavior of Impurities during ‘In-Process’ Phase Purity Analysis of an API

Organic Process Research & Development

Manufacturing a specified polymorphic form of an active pharmaceutical ingredient (API) is of imm... more Manufacturing a specified polymorphic form of an active pharmaceutical ingredient (API) is of immense importance in the pharmaceutical industry. Crystal polymorphism and transformations among different forms of APIs are studied in detail during process development. While associated impurities in API are characterized in depth for their chemical structures and properties, solid state characteristics of impurities are usually overlooked, mainly because of their presence in low levels. Herein, we discuss a case of a process impurity, BrettPhos oxide (BPO), interfering with in-process phase analysis of an API. The impact of changing the workup procedure on the impurity purging and its effect on solid form analysis of the API is highlighted. Complexities encountered due to interplay between different solid forms of BPO and API are presented. Further, phase behavior of BPO in some common process relevant solvents is established.

Research paper thumbnail of Paper Relationships between crystal structures and thermodynamic properties of phenylbutazone solvates

Crystengcomm, 2004

First published as an Advance Article on the web 20th July 2004 The relationships between the cry... more First published as an Advance Article on the web 20th July 2004 The relationships between the crystal structures and the thermodynamic properties of six phenylbutazone solvates were studied. From the crystal structures the free volume available to the solvent molecules, Vasm, the packing density of the solvent in the solvate channels, Kchan, and the lattice energy of each solvate, Elattice, were calculated and the intermolecular interactions in the solvates were identified. From the measured equilibrium vapor pressure of the solvent above each solvate and above each liquid solvent, the standard free energy,

Research paper thumbnail of Thermal studies of furosemide–caffeine binary system that forms a cocrystal

Journal of Thermal Analysis and Calorimetry, 2014

Research paper thumbnail of Novel furosemide cocrystals and selection of high solubility drug forms

Journal of Pharmaceutical Sciences, 2012

Research paper thumbnail of High solubility crystalline hydrates of Na and K furosemide salts

CrystEngComm, 2014

Furosemide–Na–trihydrate displayed aqueous solubility of about 4000 fold higher than that of furo... more Furosemide–Na–trihydrate displayed aqueous solubility of about 4000 fold higher than that of furosemide while furosemide–K–monohydrate has over 10 000 times improved solubility.

Research paper thumbnail of Relationships between crystal structures and thermodynamic properties of phenylbutazone solvates

CrystEngComm, 2004

... Toshihito Hosokawa†, Sharmistha Datta, Agam R. Sheth and David JW Grant*. Department of Pharm... more ... Toshihito Hosokawa†, Sharmistha Datta, Agam R. Sheth and David JW Grant*. Department of Pharmaceutics, College of Pharmacy, University of ... the solvates were measured using a differential scanning calorimeter (DuPont 910, TA Instruments, New Castle, DE, USA) equipped ...

Research paper thumbnail of Effect of supersaturation on the crystallization of phenylbutazone polymorphs

Crystal Research and Technology, 2005

The article describes the effect of degree of supersaturation, σ, on the crystallization of speci... more The article describes the effect of degree of supersaturation, σ, on the crystallization of specific polymorphs of phenylbutazone from its methanolic solution at 20°C. At low initial supersaturation, σ ≤ 2.0, the fraction of the metastable α polymorph in the crystallized product exceeds that of the δ polymorph, while at σ ≥ 5.0, the fraction of the stable δ polymorph increases in the crystallized product. The results are explained by the effect of supersaturation on the relative rates of nucleation and crystal growth of the polymorphs. Furthermore, the mechanism of nucleation and crystal growth also change with supersaturation. Supersaturated methanolic solutions of phenylbutazone exhibit a critical temperature at which the nucleation rates of the polymorphs decrease drastically. This effect is partly explained by the decreased mobility of phenylbutazone molecules at lower temperatures. Nucleation is most rapid when the crystallization temperature is close to the transition temperature, T t (α↔δ), between the polymorphs, α and δ. The nucleation rate decreases as the temperature difference between T t (α↔δ) and the crystallization temperature increases.

Research paper thumbnail of Computing the Relative Nucleation Rate of Phenylbutazone and Sulfamerazine in Various Solvents

Crystal Growth & Design, 2005

This work simulates the nucleation of sulfamerazine in acetone, methanol, or water, and phenylbut... more This work simulates the nucleation of sulfamerazine in acetone, methanol, or water, and phenylbutazone in diethyl ether, methanol, or acetone. A new method is developed to estimate the time of onset of nucleation from supersaturated solutions using molecular dynamics simulation and knowledge of the solubility of the solute and the density of the saturated solution. Calculations are based on the dynamics of pairs of solute molecules at extreme supersaturations instead of dynamics of molecular aggregates at practical supersaturations. First, the characteristic radial distance (CRD) specific to each solute-solvent system is identified. Next, the time evolution of the radial distribution function (RDF), g(r), at CRD is evaluated. The onset of the nucleation is taken as the time after which g(r) at the CRD remains constant. Finally, the estimated relative nucleation times are compared with those measured experimentally. The calculated and experimental nucleation times in various solvents are related linearly and by rank order. However, the ratio of the calculated to the experimental nucleation time is on the order of 10-16 for sulfamerazine and 10-14 for phenylbutazone. This discrepancy arises from the underlying assumptions that are necessarily imposed by the limitation in the number of atoms the computation can treat.

Research paper thumbnail of Isostructurality among Five Solvates of Phenylbutazone

Crystal Growth & Design, 2004

... Brooks, ‡ § Victor G. Young, Jr., ‡ and David JW Grant* †. ... (11) SAINT V6.2, Bruker Analyt... more ... Brooks, ‡ § Victor G. Young, Jr., ‡ and David JW Grant* †. ... (11) SAINT V6.2, Bruker Analytical X-ray Systems, Madison, WI, 2001. (12) Altomare, A.; Burla, MC; Camalli, M.; Cascarano, GL; Giacovazzo, C.; Guagliardi, A.; Moliterni, AGG; Polidori, G.; Spagna, R. J. Appl. Crystallogr. ...

Research paper thumbnail of Polymorphs and Cocrystals of Nalidixic Acid

Crystal Growth & Design, 2012

Research paper thumbnail of Relationships between crystal structures and thermodynamic properties of phenylbutazone solvates

CrystEngComm, 2004

... Toshihito Hosokawa†, Sharmistha Datta, Agam R. Sheth and David JW Grant*. Department of Pharm... more ... Toshihito Hosokawa†, Sharmistha Datta, Agam R. Sheth and David JW Grant*. Department of Pharmaceutics, College of Pharmacy, University of ... the solvates were measured using a differential scanning calorimeter (DuPont 910, TA Instruments, New Castle, DE, USA) equipped ...

Research paper thumbnail of Crystal structures of drugs: advances in determination, prediction and engineering

Nature Reviews Drug Discovery, 2004

Research paper thumbnail of Simultaneous Estimation Of Rifampicin And Isoniazid In Combined Dosage Forms

Indian Journal of Pharmaceutical Sciences, 2000

A simple spectrophotometric method for the simultaneous estimation of rifampicin and isoniazid in... more A simple spectrophotometric method for the simultaneous estimation of rifampicin and isoniazid in their combined pharmaceutical dosage form has been developed. The method does not require any extraction or isolation procedure. The method is simple, rapid, specific and reproducible. Recovery studies were also found to be satisfactory.

Research paper thumbnail of Mixing Effects on the Ternary Phase Diagram of Cocrystals and Gibbs Formation Energy Calculation

Research paper thumbnail of Solid State Behavior of Impurities during ‘In-Process’ Phase Purity Analysis of an API

Organic Process Research & Development

Manufacturing a specified polymorphic form of an active pharmaceutical ingredient (API) is of imm... more Manufacturing a specified polymorphic form of an active pharmaceutical ingredient (API) is of immense importance in the pharmaceutical industry. Crystal polymorphism and transformations among different forms of APIs are studied in detail during process development. While associated impurities in API are characterized in depth for their chemical structures and properties, solid state characteristics of impurities are usually overlooked, mainly because of their presence in low levels. Herein, we discuss a case of a process impurity, BrettPhos oxide (BPO), interfering with in-process phase analysis of an API. The impact of changing the workup procedure on the impurity purging and its effect on solid form analysis of the API is highlighted. Complexities encountered due to interplay between different solid forms of BPO and API are presented. Further, phase behavior of BPO in some common process relevant solvents is established.

Research paper thumbnail of Paper Relationships between crystal structures and thermodynamic properties of phenylbutazone solvates

Crystengcomm, 2004

First published as an Advance Article on the web 20th July 2004 The relationships between the cry... more First published as an Advance Article on the web 20th July 2004 The relationships between the crystal structures and the thermodynamic properties of six phenylbutazone solvates were studied. From the crystal structures the free volume available to the solvent molecules, Vasm, the packing density of the solvent in the solvate channels, Kchan, and the lattice energy of each solvate, Elattice, were calculated and the intermolecular interactions in the solvates were identified. From the measured equilibrium vapor pressure of the solvent above each solvate and above each liquid solvent, the standard free energy,

Research paper thumbnail of Thermal studies of furosemide–caffeine binary system that forms a cocrystal

Journal of Thermal Analysis and Calorimetry, 2014

Research paper thumbnail of Novel furosemide cocrystals and selection of high solubility drug forms

Journal of Pharmaceutical Sciences, 2012

Research paper thumbnail of High solubility crystalline hydrates of Na and K furosemide salts

CrystEngComm, 2014

Furosemide–Na–trihydrate displayed aqueous solubility of about 4000 fold higher than that of furo... more Furosemide–Na–trihydrate displayed aqueous solubility of about 4000 fold higher than that of furosemide while furosemide–K–monohydrate has over 10 000 times improved solubility.

Research paper thumbnail of Relationships between crystal structures and thermodynamic properties of phenylbutazone solvates

CrystEngComm, 2004

... Toshihito Hosokawa†, Sharmistha Datta, Agam R. Sheth and David JW Grant*. Department of Pharm... more ... Toshihito Hosokawa†, Sharmistha Datta, Agam R. Sheth and David JW Grant*. Department of Pharmaceutics, College of Pharmacy, University of ... the solvates were measured using a differential scanning calorimeter (DuPont 910, TA Instruments, New Castle, DE, USA) equipped ...

Research paper thumbnail of Effect of supersaturation on the crystallization of phenylbutazone polymorphs

Crystal Research and Technology, 2005

The article describes the effect of degree of supersaturation, σ, on the crystallization of speci... more The article describes the effect of degree of supersaturation, σ, on the crystallization of specific polymorphs of phenylbutazone from its methanolic solution at 20°C. At low initial supersaturation, σ ≤ 2.0, the fraction of the metastable α polymorph in the crystallized product exceeds that of the δ polymorph, while at σ ≥ 5.0, the fraction of the stable δ polymorph increases in the crystallized product. The results are explained by the effect of supersaturation on the relative rates of nucleation and crystal growth of the polymorphs. Furthermore, the mechanism of nucleation and crystal growth also change with supersaturation. Supersaturated methanolic solutions of phenylbutazone exhibit a critical temperature at which the nucleation rates of the polymorphs decrease drastically. This effect is partly explained by the decreased mobility of phenylbutazone molecules at lower temperatures. Nucleation is most rapid when the crystallization temperature is close to the transition temperature, T t (α↔δ), between the polymorphs, α and δ. The nucleation rate decreases as the temperature difference between T t (α↔δ) and the crystallization temperature increases.

Research paper thumbnail of Computing the Relative Nucleation Rate of Phenylbutazone and Sulfamerazine in Various Solvents

Crystal Growth & Design, 2005

This work simulates the nucleation of sulfamerazine in acetone, methanol, or water, and phenylbut... more This work simulates the nucleation of sulfamerazine in acetone, methanol, or water, and phenylbutazone in diethyl ether, methanol, or acetone. A new method is developed to estimate the time of onset of nucleation from supersaturated solutions using molecular dynamics simulation and knowledge of the solubility of the solute and the density of the saturated solution. Calculations are based on the dynamics of pairs of solute molecules at extreme supersaturations instead of dynamics of molecular aggregates at practical supersaturations. First, the characteristic radial distance (CRD) specific to each solute-solvent system is identified. Next, the time evolution of the radial distribution function (RDF), g(r), at CRD is evaluated. The onset of the nucleation is taken as the time after which g(r) at the CRD remains constant. Finally, the estimated relative nucleation times are compared with those measured experimentally. The calculated and experimental nucleation times in various solvents are related linearly and by rank order. However, the ratio of the calculated to the experimental nucleation time is on the order of 10-16 for sulfamerazine and 10-14 for phenylbutazone. This discrepancy arises from the underlying assumptions that are necessarily imposed by the limitation in the number of atoms the computation can treat.

Research paper thumbnail of Isostructurality among Five Solvates of Phenylbutazone

Crystal Growth & Design, 2004

... Brooks, ‡ § Victor G. Young, Jr., ‡ and David JW Grant* †. ... (11) SAINT V6.2, Bruker Analyt... more ... Brooks, ‡ § Victor G. Young, Jr., ‡ and David JW Grant* †. ... (11) SAINT V6.2, Bruker Analytical X-ray Systems, Madison, WI, 2001. (12) Altomare, A.; Burla, MC; Camalli, M.; Cascarano, GL; Giacovazzo, C.; Guagliardi, A.; Moliterni, AGG; Polidori, G.; Spagna, R. J. Appl. Crystallogr. ...

Research paper thumbnail of Polymorphs and Cocrystals of Nalidixic Acid

Crystal Growth & Design, 2012

Research paper thumbnail of Relationships between crystal structures and thermodynamic properties of phenylbutazone solvates

CrystEngComm, 2004

... Toshihito Hosokawa†, Sharmistha Datta, Agam R. Sheth and David JW Grant*. Department of Pharm... more ... Toshihito Hosokawa†, Sharmistha Datta, Agam R. Sheth and David JW Grant*. Department of Pharmaceutics, College of Pharmacy, University of ... the solvates were measured using a differential scanning calorimeter (DuPont 910, TA Instruments, New Castle, DE, USA) equipped ...