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Desapareciendo y reapareciendo polimorfos. El sistema de benzocaína: ácido pícrico
J O Henck1, J Bernstein, A Ellern
1Institut für Pharmakognosie der Universität Innsbruck Innrain 52, Josef-Moeller-Haus, 6020 Innsbruck, Austria.
Journal of the American Chemical Society
|July 18, 2001
Resumen
La investigación del sistema de benzocaína (BC) y ácido pícrico (PA) reveló métodos para cristalizar formas polimórficas evasivas. Comprender el comportamiento térmico es clave para obtener estructuras cristalinas metastables.
Área de la Ciencia:
- La cristalografía es una técnica de cristalografía.
- Ciencia de los materiales Ciencia de los materiales.
- Ingeniería Química Ingeniería Química.
Sus antecedentes:
- El complejo benzocaína: ácido pícrico (BC:PA) 1: 1 previamente exhibió una
- Desaparición del polimorfo desaparecido.
- una forma metastable que es difícil de aislar.
- El polimorfismo en los cocristales farmacéuticos es crítico para la estabilidad y biodisponibilidad de los fármacos.
Objetivo del estudio:
- Para reinvestigar el sistema de benzocaína: ácido pícrico (BC:PA).
- Desarrollar procedimientos robustos de cristalización para varias fases de BC:PA.
- Comprender las condiciones para la cristalización de formas polimórficas metastables.
Principales métodos:
- Termomicroscopia y calorimetría de barrido diferencial (DSC) para el análisis térmico.
- Espectroscopia de resonancia magnética nuclear (RMN) en estado sólido.
- Cristalografía de rayos X para la determinación estructural.
- Análisis de conjuntos de gráficos para la caracterización de enlaces de hidrógeno.
Principales resultados:
- Se estableció el diagrama de fases del sistema BC:PA.
- Se identificaron y caracterizaron cuatro fases cristalinas distintas: dos complejos 1:1, un hidrato 1:1 y un complejo 2:1.
- El análisis estructural reveló patrones específicos de enlace de hidrógeno en cada fase.
- Se desarrollaron estrategias para cristalizar formas metastables basadas en el comportamiento térmico.
Conclusiones:
- Un análisis térmico exhaustivo combinado con métodos calorimétricos permite la cristalización de formas polimórficas metastables difíciles de obtener.
- Comprender el comportamiento de fase es crucial para controlar la cristalización de los sistemas cocristalinos.
- Este estudio proporciona un marco para acceder a los polimorfos metastables en otros sistemas químicos.
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