Novel Solid Forms of Cardarine/GW501516 and Their Characterization by X-Ray Diffraction, Thermal, Computational, FTIR, and UV Analysis.

Cardarine (C21H18F3NO3S2), better known by the popular name of GW501516, is a peroxisome proliferator-activated receptor delta (PPR-δ) agonist that presents potential use in the approach of cardiovascular diseases and metabolic disorders, dyslipidemia, and insulin resistance. The capability of cardarine to exhibit new solid forms by recrystallization from a broad class of solvents was explored. A total of four new solid forms were obtained: a new polymorph of cardarine (C21H18F3NO3S2), the cardarine: 4,4'-bipyridine cocrystal (C21H18F3NO3S2·0.5C10H8N2), the cardarine methanol solvate (C21H18F3NO3S2·CH3OH), and the cardarine dimethylformamide solvate (C21H18F3NO3S2·C3H7NO). Moreover, two derivatives of cardarine were obtained, in the form of the mono-oxidized cardarine structure (C21H18F3NO4S2) and the dioxidized cardarine structure (C21H18F3NO5S2). The formation process was proven by the determination of their crystal structures using single crystal X-ray diffraction and followed by their lattice energies evaluation. Further investigations have been conducted by powder X-ray diffraction, DTA/TGA thermal analysis, and FTIR spectroscopy. The stability and solubility were analyzed as well.