Thermodynamic Characterization of Three Polymorphic Forms of Piracetam

Picciochi, Ricardo; Diogo, Hermı́nio P.; Piedade, Manuel E. Minas da

doi:10.1002/jps.22294

Cited by 20 publications

(27 citation statements)

References 39 publications

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“…III." 4 Maher et al reported a ∆G -T diagram exhibiting endothermic transitions II→I and III→I below 363 K and below 368 K respectively, thus leading to the conclusion that form III is the more stable form below 368 K. 5 Céolin et al reported that the endothermic transitions III→I and II→I occur at 392 K and 399 K respectively, thus inferring that form II is the more stable phase below 392 K. 6 Although a tendency can be observed that form III is the more stable phase at room temperature, the large variation of solid-solid transition temperatures in the different papers warrants an alternative approach to determine the stability hierarchy of the polymorphs without ambiguity. In this paper, it will be demonstrated how the stability hierarchy can be inferred from experimental pressure-temperature diagrams.…”

Section: The Stability Hierarchy Of the Three Solid Forms Of Piracetammentioning

confidence: 99%

Stability hierarchy between Piracetam forms I, II, and III from experimental pressure–temperature diagrams and topological inferences

Toscani

Céolin

Minassian

et al. 2016

International Journal of Pharmaceutics

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The trimorphism of the active pharmaceutical ingredient piracetam is a famous case of polymorphism that has been frequently revisited by many researchers. The phase relationships between forms I, II, and III were ambiguous because they seemed to depend on the heating rate of the DSC and on the history of the samples or they have not been observed at all (equilibrium II-III). In the present paper, piezo-thermal analysis and high-pressure differential thermal analysis have been used to elucidate the positions of the different solid-solid and solid-liquid equilibria. The phase diagram, involving the three solid phases, the liquid phase and the vapor phase, has been constructed. It has been shown that form III is the high-pressure, low-temperature form and the stable form at room temperature. Form II is stable under intermediary conditions and form I is the low pressure, high temperature form, which possesses a stable melting point. The present paper demonstrates the strength of the topological approach based on the Clapeyron equation and the alternation rule when combined with high-pressure measurements.

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Section: The Stability Hierarchy Of the Three Solid Forms Of Piracetammentioning

confidence: 99%

Stability hierarchy between Piracetam forms I, II, and III from experimental pressure–temperature diagrams and topological inferences

Toscani

Céolin

Minassian

et al. 2016

International Journal of Pharmaceutics

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“…Throughout the literature, there is some conflicting evidence about the stability hierarchy of Forms II and III. However, Form III is the usual commercial sample and this could suggest that this form is the thermodynamically most stable phase under normal conditions of temperature and pressure, as attested by former studies [3,[5][6][7][8][9][10][11]. However, a previously reported state diagram of piracetam revealed that, due to a measured III-I transition temperature lower than that of the II-I, Form II was the most stable form at ordinary pressures [4].…”

Section: Introductionmentioning

confidence: 86%

“…This drug is usually administered in solid form. No less than five polymorphs of this substance have been characterized and subsequently reported in the literature [1][2][3][4][5][6][7][8]. The most commonly studied polymorphic forms are referenced as I, II and III.…”

Section: Introductionmentioning

confidence: 99%

“…The most commonly studied polymorphic forms are referenced as I, II and III. The first solid form crystallizes in a monoclinic lattice and is the stable form at high temperature [3][4][5][6][7][9][10][11]. Its melting point is ~ 435 K. The second and the third polymorphs are reported to crystallize in triclinic and monoclinic systems, respectively [2].…”

Section: Introductionmentioning

confidence: 99%

“…The changes of the molar volume ∆V at the transition points were obtained from the plots of figure 2 at the corresponding transition temperature. The resulting slopes of the two-phase equilibrium curves are then given in table7.…”

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confidence: 99%

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Kinetics of the (solid + solid) transformations for the piracetam trimorphic system: Incidence on the construction of the p – T equilibrium phase diagram

Corvis

Biré

Alzina³

et al. 2016

The Journal of Chemical Thermodynamics

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The three common polymorphs of piracetam have been characterized by associating thermal analysis, X-ray diffraction and densimetry. DSC experiments showed that the solid-solid transition temperature between Forms II and I and between Forms III and I is scan-rate dependent. The transition temperatures decrease when the DSC scan rate decreases and the thermodynamic temperatures were confirmed by isothermal X-ray diffraction. These new results in terms of temperature and enthalpy of transition allow us to propose a new equilibrium phase diagram establishing the relative thermodynamic stability of the three common polymorphs of piracetam as a function of the temperature and the pressure. The diagram suggests that Form II presents a small stability domain located just above the stability domain of Form I. As a consequence, Form I should transform into Form II, which itself can turn into Form III when placed under pressure.

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Investigation of polymorphic transitions of piracetam induced during wet granulation

Potter

Kollamaram

Żegliński

et al. 2017

European Journal of Pharmaceutics and Biopharmaceutics

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Thermodynamic Characterization of Three Polymorphic Forms of Piracetam

Cited by 20 publications

References 39 publications

Stability hierarchy between Piracetam forms I, II, and III from experimental pressure–temperature diagrams and topological inferences

Stability hierarchy between Piracetam forms I, II, and III from experimental pressure–temperature diagrams and topological inferences

Kinetics of the (solid + solid) transformations for the piracetam trimorphic system: Incidence on the construction of the p – T equilibrium phase diagram

Investigation of polymorphic transitions of piracetam induced during wet granulation

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