Glossary

Polymorphism

Polymorphism is the ability of a solid material to form different crystalline structures (synonyms:  forms, modifications).  

Although different modifications of a polymorph have the same chemical structure, they differ in the physical properties such as:

 

This influences the processability of drug substances and the performance of drug products, such as:

  • Stability
  • Absorption into the body
  • Dissolution (rate)
  • Bioavailability

 

That is why polymorphism is an important topic for the pharmaceutical and also the food field.

The different modifications of a polymorph can be characterized with differential scanning calorimetry (DSC).

У вас есть вопросы?

Наши специалисты будут рады помочь вам.

Свяжитесь с нами

Подходящие продукты для вашего измерения

DSC measurement on paracetamol 1] Source: M. Szelagiewicz et al., Therm. Anal. Cal., 57 (1999) 23
Example

Polymorphism of Paracetamol

The figure depicts the two heatings of a paracetamol sample (initial mass: 2.6 mg). The heating rates as well as the cooling rate of the segment between both heatings amount to 10 K/min.

In the first heating, a peak at 169°C (onset temperature) is detected. This Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).melting temperature is typical for the monoclinic form I of paracetamol. [1]

During cooling at 10 K/min, no crystallization occurs. Crystallization takes place during the second heating at 72°C (onset temperature) to form another modification with Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).melting point at 157°C. This is typical for the orthorhombic form II of paracetamol [1].