Journal ArticleDOI
Crystallization of polymorphs : the effect of solvent
Sohrab Khoshkhoo,Jamshed Anwar +1 more
Reads0
Chats0
TLDR
In this article, the effect of solvent in crystallization of polymorphs has been studied using the drug sulphathiazole as a model compound, and it is considered that the solvent acts by selective adsorption to certain faces of some polymorphs and thereby either inhibits their nucleation or retards their growth to the advantage of others.Abstract:
The effect of solvent in crystallization of polymorphs has been studied using the drug sulphathiazole as a model compound. The solubilities of the four polymorphic forms of sulphathiazole were determined as a function of temperature in various solvents. Within the temperature ranges studied, the rank order of solubility of the polymorphs was the same in all solvent systems. On the basis of this knowledge of the temperature dependence of the solubilities, recrystallization experiments, in which the supersaturation was systematically varied, were carried out in an endeavour to isolate each of the polymorphic forms from each solvent system. These recrystallization experiments reveal that not all of the know polymorphic forms can be crystallized from any given solvent by varying the supersaturation. Indeed some solvents selectively favour the crystallization of a particular form of forms. The authors conclude that thermodynamic effects are not responsible for the selective behaviour of a solvent. A kinetic mechanism is proposed. It is considered that the solvent acts by selective adsorption to certain faces of some of the polymorphs, and thereby either inhibits their nucleation or retards their growth to the advantage of others.read more
Citations
More filters
Book ChapterDOI
Crystalline Polymorphism of Organic Compounds
TL;DR: A wide variety of techniques appropriate to the study of organic crystalline polymorphism and pseu-dopolymorphism is then surveyed, ranging from simple crystal density measurement to observation of polymorphic transformations using variable-temperature synchrotron X-ray diffraction methods.
Journal ArticleDOI
High-throughput crystallization: polymorphs, salts, co-crystals and solvates of pharmaceutical solids
Sherry L. Morissette,Orn Almarsson,Matthew Peterson,Julius F. Remenar,Michael Read,Anthony V. Lemmo,Steve Ellis,Michael J. Cima,Colin R. Gardner +8 more
TL;DR: The impact of form diversity encompasses issues of stability and bioavailability, as well as development considerations such as process definition, formulation design, patent protection and regulatory control.
Journal ArticleDOI
Thermal analysis and calorimetric methods in the characterisation of polymorphs and solvates
TL;DR: In this paper, the authors present a review of the use of thermal analysis for the analysis of polymorphism and pseudo-polymorphism in drug substances and excipients, including solvates and impurities.
Journal ArticleDOI
Crystallization processes in pharmaceutical technology and drug delivery design
B.Yu Shekunov,Peter York +1 more
TL;DR: In this article, industrial and regulatory aspects of crystallization are briefly reviewed with reference to solid-state properties of pharmaceuticals, incorporating wider definition to include precipitation and solid state transitions, and recent developments in supercritical fluid particle technology is considered in relationship to the areas discussed.
Journal ArticleDOI
Significance of controlling crystallization mechanisms and kinetics in pharmaceutical systems
TL;DR: The illusion of process control is motivated by a crystallization process that yields the desired productssolid phase modification, shape, or size distributions by the robust analytical methods used for solid state characterization.
References
More filters
Journal ArticleDOI
Equation of state calculations by fast computing machines
TL;DR: In this article, a modified Monte Carlo integration over configuration space is used to investigate the properties of a two-dimensional rigid-sphere system with a set of interacting individual molecules, and the results are compared to free volume equations of state and a four-term virial coefficient expansion.
Book
Computer Simulation of Liquids
Michael P. Allen,D. J. Tildesley +1 more
TL;DR: In this paper, the gear predictor -corrector is used to calculate forces and torques in a non-equilibrium molecular dynamics simulation using Monte Carlo methods. But it is not suitable for the gear prediction problem.
Journal ArticleDOI
Pharmaceutical Applications of Polymorphism
John K. Haleblian,Walter McCrone +1 more
TL;DR: Polymorphism is the ability of any element or compound to crystallize as more than one distinct crystal species (e.g., carbon as cubic diamond or hexagonal graphite).
Journal ArticleDOI
The kinetics of solvent-mediated phase transformations
P.T. Cardew,Roger J. Davey +1 more
TL;DR: In this article, a model is developed for the case of a polymorphic phase transformation, which involves the dissolution of the metastable phase and growth of nuclei of the stable phase.