A Novel Method for Estimation of Transition Temperature for Polymorphic Pairs in Pharmaceuticals Using Heat of Solution and Solubility Data.

Urakami, Koji; Shono, Yasushi; Higashi, Atsuya; Umemoto, Kazuichi; Godo, Masayuki

doi:10.1248/cpb.50.263

Cited by 48 publications

(36 citation statements)

References 15 publications

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“…This effect was observed with the metastable polymorphs of acetazolamide, carbamazepine, and indomethacin. 2 However, this free energy difference between the stable and metastable forms can also provide the driving force for metastable → stable transformation in the dissolution medium. As a result, the observed difference in dissolution rate can be much lower than the predicted values.…”

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confidence: 99%

Influence of processing-induced phase transformations on the dissolution of theophylline tablets

Debnath

Suryanarayanan

2004

AAPS PharmSciTech

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INTRODUCTIONThe object of this investigation was to evaluate the influence of (1) processing-induced decrease in drug crystallinity and (2) phase transformations during dissolution, on the performance of theophylline tablet formulations. Anhydrous theophylline underwent multiple transformations (anhydrate → hydrate → anhydrate) during processing. Although the crystallinity of the anhydrate obtained finally was lower than that of the unprocessed drug, it dissolved at a slower rate. This decrease in dissolution rate was attributed to the accelerated anhydrate to hydrate transformation during the dissolution run. Water vapor sorption studies proved to be a good predictor of powder dissolution behavior. While a decrease in crystallinity was brought about either by milling or by granulation, the effect on tablet dissolution was pronounced only in the latter. Tablet formulations prepared from the granules exhibited higher hardness, longer disintegration time, and slower dissolution than those containing the milled drug. The granules underwent plastic deformation during compression resulting in harder tablets, with delayed disintegration. The high hardness coupled with rapid anhydrate → hydrate transformation during dissolution resulted in the formation of a hydrate layer on the tablet surface, which further delayed tablet disintegration and, consequently, dissolution. Phase transformations during processing and, more importantly, during dissolution influenced the observed dissolution rates. Product performance was a complex function of the physical state of the active and the processing conditions.The physicochemical properties of pharmaceuticals, including solubility and dissolution rate, can be influenced by the degree of crystallinity, solvation state, and crystal form. At room temperature, the anhydrate forms of ampicillin, theophylline, and glutethimide have a higher dissolution rate than their corresponding hydrates. 1 This difference in dissolution rate can be attributed to the difference in the free energy of hydration.1 Similarly, metastable forms, because of their higher free energy, are expected to dissolve more rapidly than their corresponding stable forms. This effect was observed with the metastable polymorphs of acetazolamide, carbamazepine, and indomethacin.2 However, this free energy difference between the stable and metastable forms can also provide the driving force for metastable → stable transformation in the dissolution medium. As a result, the observed difference in dissolution rate can be much lower than the predicted values. 3Although the physical form of a drug substance is carefully selected for dosage form manufacture, the processing conditions will determine the solid state of the drug in the final product. During tablet manufacture, processing steps may include milling, granulation, drying, and compression. Particle size as well as degree of crystallinity can be profoundly affected by milling as has been observed in case of griseofulvin. 4 The use of a binder solution for wet gra...

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confidence: 99%

Influence of processing-induced phase transformations on the dissolution of theophylline tablets

Debnath

Suryanarayanan

2004

AAPS PharmSciTech

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“…for estimating transition temperatures for enantiotropic polymorphs, or for estimation of melting properties. Such extrapolations are frequently done on the basis of assuming linear van't Hoff plots [13][14][15][16]. It has been shown [11] that a linear model will generally lead to poor accuracy, but with a proper choice of model extrapolation of van't Hoff curves to ln xeq = 0 can produce a reasonable estimate of the melting properties of the pure solute.…”

Section: Analysis and Discussionmentioning

confidence: 99%

Thermodynamics of risperidone and solubility in pure organic solvents

Mealey

Svärd

Rasmuson

2014

Fluid Phase Equilibria

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The solid-liquid solubility of the thermodynamically stable form I of the drug risperidone has been determined by a gravimetric method in nine pure organic solvents in the temperature range 278.15-323.15 K. The melting temperature and associated enthalpy of fusion of risperidone form I has been determined by differential scanning calorimetry (DSC) to be 442.38 K and 43.94 kJ mol -1 , respectively. The heat capacity of the solid form I and the melt have been determined over a range of temperatures by temperature-modulated DSC, and extrapolated data has been used to calculate the Gibbs energy, enthalpy and entropy of fusion from ambient temperature up to the melting point. The ideal solubility within a Raoult's law framework is obtained from the Gibbs energy of fusion, and the solution activity coefficient at equilibrium in the nine solvents quantified. Solutions in all solvents exhibit positive deviation from Raoult's law, with the highest solubility (closest to ideality) in toluene, an aprotic apolar solvent. The solubility curves plotted in a van't Hoff graph show non-linear behaviour and are well-approximated by a second order polynomial.

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“…There are some discrepancies in the literature 5,[25][26][27] with respect to the temperature at which form III (monoclinic, P2 1 /c) of CBZ converts to form I (triclinic, P1 4 ). Theoretical calculations 26 predicted that at 77.6 • C, the monoclinic-to-triclinic phase transition is attained.…”

Section: Quantitative Phase Analyses Of Cbz Forms I and Iiimentioning

confidence: 99%

Quantitative Phase Analyses Through The Rietveld Method with X-Ray Powder Diffraction Data of Heat-Treated Carbamazepine Form III

Antônio

Benini

Ferreira

et al. 2011

Journal of Pharmaceutical Sciences

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A Novel Method for Estimation of Transition Temperature for Polymorphic Pairs in Pharmaceuticals Using Heat of Solution and Solubility Data.

Cited by 48 publications

References 15 publications

Influence of processing-induced phase transformations on the dissolution of theophylline tablets

Influence of processing-induced phase transformations on the dissolution of theophylline tablets

Thermodynamics of risperidone and solubility in pure organic solvents

Quantitative Phase Analyses Through The Rietveld Method with X-Ray Powder Diffraction Data of Heat-Treated Carbamazepine Form III

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