Observation of Polymorphic Transition of Efavirenz during Heating by Raman Spectroscopy

Efavirenz as an anti-HIV type 1 drug has a lot of polymorph forms. The references reported it had 23 different polymorph forms include amorphous. But the only form I used in pharmaceutical market widespread which known as a stable form with poor solubility properties. Common knowledge that besides a stable form there is a meta-stable form which has more benefit in solubility. One of the meta-stable forms aim to study in this research was the form which result from methanol recrystallization. Characterization of form was slightly different both in diffractogram patterns from XRPD (X-ray Powdered Diffractometry) and the thermogram from DSC (Differential Scanning Calorimetry) comparing with a patent. Others characterizations were carried out such as Infrared (IR) vibration spectrums with IR absorption (Fourier Transform IR) and IR scattering (Raman Spectroscopy) to described polymorph functional groups response. To re-examined the polymorphic transition information from DSC the in-situ temperature dependent of Raman spectroscopy was conducted. There has only a little temperature shifting, from the thermogram the polymorphic transition of form taken place in the range 108.4110.4oC, but from Raman spectral information happen in 100115oC.