What is a polymorph?

  • From wikipedia: “One of several forms of crystal structure of a material displaying polymorphism”
  • Most organic molecules form various crystalline structures: A polymorph refers to one of these well-defined crystalline structures, where the molecules are attached to each other in a “repeatable pattern”.
  • An example of two polymorphic forms is graphite and diamond: They are made of the same molecules/atoms, but behave and look very different.
  • Almost all pharmaceutical drugs consists of a crystal form of the active ingredient, i.e. the active ingredient might be present in different polymorphic forms.
  • Different polymorphs have different stability – it depends on the “strength of attachment” to the neighbor molecules.
  • According to the “laws of nature” the molecules will always try to obtain the more stable structure. I.e. eventually the  most stable polymorph “will win”. (However, it might take decades or more)
  • In development of a pharmaceutical drug, it is usually desired to use the most stable polymorph to avoid the risk of transformation into another form.
  • The more stable polymorph has a lower solubility and dissolution rate.
  • Different polymorphic forms can be produced by exposing the molecule to different crystallisation conditions.
  • According to regulatory guidelines a polymorph screening is required to get a new drug approved.

Please contact us to know more about our services in regard to polymorph examinations. Click here if you want to know more about the reasons for controlling the polymorphic form of your product.

Almost all compounds can crystallize in different ways. The different crystals have different properties in relation to solubility and stability.