Polymorphic Forms of Furosemide Characterized by THz Time Domain Spectroscopy

Abstract

Terahertz time domain spectroscopy (THz-TDS) is applied in transmission to identify the five forms of modifications of furosemide and one commercial product from 0.3 THz to 1.6 THz at room temperature. The different absorption spectra of the different forms are sensitive to crystal structures. Density function theory (DFT) calculation was used to understand the vibrational modes of furosemide in the THz region. X-ray powder diffractometry (XRPD) was applied to confirm the different forms of modifications. The results demonstrate that THz-TDS is a potential analytical technique in investigating polymorphic forms in the pharmaceutical fields.

Optical properties of Meloxicam in the far-infrared spectral region

“…Application of THz waves have been diverse in many areas such as molecular spectroscopy[1], solid state physics[2,3], biology[4–6], imaging[7], and pharmaceuticals[8–11]. This frequency range covers collective vibrational or torsional modes in condensed-phase media, and rotational and vibrational modes of molecules.…”

“…In their study Ge et al presented clear identification of 5 different polymorphs of furosemide using their spectral features between 0.2 THz and 1.6 THz. [8] In a study by Zeitler et al the sensitivity of THz spectroscopy has been exploited in order to study temperature dependent polymorphism of Carbamazepine in the frequency range between 0.1 THz and 2.85 THz. [16] In a similar study by Sibik et al crystallization and phase changes of paracetamol was successfully followed by terahertz.…”