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• Zhao, Y
• Bao, Y
• Wang, J
• Rohani, S
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• Wang, J
• Rohani, S
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• Bao, Y
• Wang, J
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Pharmaceutics 2012, 4(1), 164-178; doi:10.3390/pharmaceutics4010164

Article

In Situ Focused Beam Reflectance Measurement (FBRM), Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) and Raman Characterization of the Polymorphic Transformation of Carbamazepine

Yingying Zhao ^1,2,3 , Ying Bao ¹ , Jingkang Wang ¹  and Sohrab Rohani ^2,*

¹ State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China ² Department of Chemical and Biochemical Engineering, the University of Western Ontario, London, ON N6A 5B9, Canada ³ Engineering Research Center of Seawater Utilization Technology of Ministry of Education, Hebei University of Technology, Tianjin 300130, China

* Author to whom correspondence should be addressed.

Received: 5 January 2012; in revised form: 20 January 2012 / Accepted: 31 January 2012 / Published: 9 February 2012

(This article belongs to the Special Issue Solid Dosage Forms)

Download PDF Full-Text [989 KB, uploaded 9 February 2012 08:58 CET]

Abstract: The objective of this work was to study the polymorphic transformation of carbamazepine from Form II to Form III in 1-propanol during seeded isothermal batch crystallization. First, the pure Form II and Form III were obtained and characterized. Then their solubilities and metastable zone limits were measured by in-situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and focused beam reflectance measurement (FBRM). A transition temperature at about 34.2 °C was deduced suggesting the enantiotropic nature of this compound over the studied temperature range. To quantify the polymorph ratio during the transformation process, a new in-situ quantitative method was developed to measure the fraction of Form II by Raman spectroscopy. Successful tracking of the nucleation of the stable form and the transformation from Form II to Form III during isothermal crystallization was achieved by Raman spectroscopy and FBRM. The results from these three in-situ techniques, FBRM, FTIR and Raman were consistent with each other. The results showed a strong dependency on the amount of seeds added during isothermal crystallization.

Keywords: carbamazepine; polymorph transformation; in-situ quantitative method; in-situ analytical techniques

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