Heat of Fusion Measurement of a Low Melting Polymorph of Carbamazepine That Undergoes Multiple-Phase Changes During Differential Scanning Calorimetry Analysis

Behme, Robert J.; Brooke, Dana

doi:10.1002/jps.2600801016

Cited by 142 publications

(99 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These dissolving solvents were chosen to correspond with those used in previous studies. [9][10][11][12] The plots in Fig. 3 show the concentrations attained in solution for each polymorphic pair as a function of time in the presence of an excess of the solid phase.…”

Section: Resultsmentioning

confidence: 99%

“…2 respectively, which are in good agreement with those reported previously (83.4, 78.4, 73°C, respectively). [9][10][11] Differences between these values could be due to such factors as equipment, chemical purity, polymorphic purity and degree of crystallinity. It is noteworthy that the seratrodast polymorphic pair could be correctly determined to be enantiotropic with a transition temperature at 84.9°C, even though the DSC curves showed a typical monotropic pattern (exothermal solid-solid transition was observed).…”

Section: Resultsmentioning

confidence: 99%

“…In previous studies, [9][10][11][12][13][14][15] this equation has been widely applied for the estimation of transition temperature for the enantiotropic polymorphic pairs. At a temperature of T 1 , the logarithmic solubilities of Form A and B in a polymorphic pair are written as Eqs.…”

Section: Theoreticalmentioning

confidence: 99%

“…For these reasons, a number of studies on the estimation of transition temperature have been reported until now. [9][10][11][12][13][14][15] In these studies, transition temperature has been estimated by linear extrapolation of van't Hoff plots (logarithmic solubility versus reciprocal of absolute temperature plots) for each polymorph; the temperature at which these extrapolated lines intersect is the transition temperature.…”

mentioning

confidence: 99%

See 3 more Smart Citations

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

Urakami

Shono

Higashi

et al. 2002

CHEMICAL & PHARMACEUTICAL BULLETIN

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Theoreticalmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

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

Urakami

Shono

Higashi

et al. 2002

CHEMICAL & PHARMACEUTICAL BULLETIN

View full text Add to dashboard Cite

“…Forms I and III of the drug constitute an enantiotropic pair, whose relative thermodynamic stability changes at 70 °C. Below this temperature, Form III is most stable, while above this temperature, Form I becomes more stable (McGregor et al, 2004;Behme, Brook, 1991;Lowes et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

Thermoanalytical studies of carbamazepine: hydration/dehydration, thermal decomposition, and solid phase transitions

Pinto¹,

Ambrozini²,

Ferreira³

et al. 2014

Braz. J. Pharm. Sci.

View full text Add to dashboard Cite

Carbamazepine (CBZ), a widely used anticonvulsant drug, can crystallize and exhibits four polymorphic forms and one dihydrate. Anhydrous CBZ can spontaneously absorb water and convert to the hydrate form whose different crystallinity leads to lower biological activity. The present study was concerned to the possibility of recovering the hydrated form by heating. The thermal behavior of spontaneously hydrated carbamazepine was investigated by TG/DTG-DTA and DSC in dynamic atmospheres of air and nitrogen, which revealed that the spontaneous hydration of this pharmaceutical resulted in a Form III hydrate with 1.5 water molecules. After dehydration, this anhydrous Form III converted to Form I, which melted and decomposed in a single event, releasing isocyanic acid, as shown by evolved gas analysis using TG-FTIR. Differential scanning calorimetry analyses revealed that Form III melted and crystallized as Form I, and that subsequent cooling cycles only generated Form I by crystallization. Solid state decomposition kinetic studies showed that there was no change in the substance after the elimination of water by heating to 120 °C. Activation energies of 98 ± 2 and 93 ± 2 kJ mol -1 were found for the hydrated and dried samples, respectively, and similar profiles of activation energy as a function of conversion factor were observed for these samples. Uniterms:Carbamazepine/thermal analysis. Polymorphism. Hydrate. Dehydration.A carbamazepina (CBZ) é um anticonvulsivante frequentemente utilizado no Brasil e em vários países. Ela apresenta quatro formas polimórficas e um diidrato. Todas as formas são ativas farmacologicamente, porém a Forma III é a preferível do ponto de vista farmacêutico, em função de suas propriedades físico-químicas. Entretanto, essa forma é altamente higroscópica, podendo converter-se ao diidrato, menos ativo biologicamente. Nesse trabalho propõe-se avaliar o comportamento térmico da forma hidratada, visando à recuperação da forma ativa, por aquecimento. Para tanto, foi feito um estudo do comportamento térmico por TG/DTG-DTA e DSC em atmosfera dinâmica de ar e nitrogênio, que evidenciou hidratação espontânea da Forma III, gerando um hidrato contendo 1,5 moléculas de água. Essa forma sofre desidratação, seguida de fusão e conversão para a Forma I. Segue-se a decomposição em uma única etapa, na qual ocorre liberação do ácido isociânico, conforme análise de gases evolvidos, por termogravimetria acoplada ao infravermelho (TG-FTIR). Estudos por calorimetria exploratória diferencial mostraram que a Forma III se funde e se cristaliza imediatamente na Forma I, durante o aquecimento. A Forma I também se funde e ciclos de aquecimento/resfriamento posteriores evidenciaram que a substância se cristaliza apenas na Forma I por resfriamento. Estudos cinéticos da decomposição, em estado sólido, mostraram que não há alteração na substância pela eliminação da água por aquecimento, sendo determinados valores de energia de ativação da ordem de 98 ± 2 e 93 ± 2 kJ mol -1 , respectivamente, para a amostra hidratada e submeti...

show abstract

Polymorphs, Solvates and Hydrates

Threlfall

2001

Handbook of Vibrational Spectroscopy

View full text Add to dashboard Cite

The sections in this article are Introduction – The Nature of Polymorphism and Solvation Mid‐Infrared Spectroscopy Quantitative Mid‐Infrared Measurements Burger's Infrared Rule Stability Near‐Infrared Spectroscopy R aman Spectroscopy Infrared and R aman Microspectroscopy

show abstract

Heat of Fusion Measurement of a Low Melting Polymorph of Carbamazepine That Undergoes Multiple-Phase Changes During Differential Scanning Calorimetry Analysis

Cited by 142 publications

References 8 publications

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

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

Thermoanalytical studies of carbamazepine: hydration/dehydration, thermal decomposition, and solid phase transitions

Polymorphs, Solvates and Hydrates

Contact Info

Product

Resources

About