Differential Molecular Interactions of Telmisartan: Molecular-Level Insights from Spectral and Computational Studies

In this study, we investigated differential molecular interactions of crystalline and amorphous forms of telmisartan (TEL), which is a non-peptide angiotensin-II receptor antagonist commonly used in the management of hypertension. Amorphous telmisartan (AM-TEL) was prepared using quench cooling of the melt. The analysis of solid-state properties of AM-TEL using differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD) confirmed formation of AM-TEL. Based on a comparative analysis of molecular interactions using spectral (FTIR and 13C solid-state NMR) and computational tools, we demonstrated that amorphous telmisartan shows altered molecular interactions. Molecular dynamics simulation of amorphous and crystalline forms demonstrate that the amorphous form retained some of the molecular interactions in its disordered molecular arrangement, with a relatively stronger (decrease in bond length) but lesser (up to only 2.6 % of the population) hydrogen bonding network as compared with the crystalline counterpart (up to 76% of the population)