Varenicline L-tartrate Crystal Forms: Characterization Through Crystallography, Spectroscopy, and Thermodynamics

Thermodynamic Stability Considerations for Isostructural Dehydrates

“…7,8 The eutectic-melting method has been successfully applied to anhydrous polymorphic systems of glycine, D-mannitol, tazofelone, and varenicline L-tartrate. 8,9 Nonstoichiometric hydrates are a class of crystalline hydrates that can incorporate a range of water levels as a function of temperature and water vapor pressure. 10 These hydrates can demonstrate the presence of connected channels within the crystalline lattice that allow for efficient and reversible uptake of water.…”

Studies on the crystal structure and arrangement of water in sitagliptinl-tartrate hydrates

“…The thermal deamination of sitagliptin was investigated by Sonune et al, 29 and the thermal decomposition of a pharmaceutical L-tartrate salt is reported by Murphy et al and Brahadeeswaran et al 22,30 In both cases, thermal decomposition took place above the melting onset. In Sonune's study, the mass of the thermal degradation products indicated the loss of mass (17; NH 3 + ) from the parent drug molecule.…”

“…Due to the propensity of water to interact and coordinate with ions, salts often form hydrates. 18 Since hydrogen tartrate anions are prone to link into infinite chains, these salts frequently exhibit a channel hydrate struc-ture like L-histidinium-L-tartrate hemihydrate, 19 saxagliptin hydrogen tartrate hemihydrate, 20 LY297802 tartrate, 21 varenicline L-tartrate 22 and silver hydrogen LIJ+)-tartrate. 23 Sitagliptin L-tartrate can crystallize in five different hydrate forms.…”

Polymorphism and Solvatomorphism 2010

“…51 The thermodynamics associated with the two nonsolvated forms of varenicline tartrate have been studied using thermal and spectroscopic means, with the aim of determining which crystal form would be most appropriate for formulation in a tablet and which would be appropriate in an aqueous vehicle. 52 Solid-state 14 N nuclear quadrupole resonance has been used to study two nonsolvated and one monohydrate of piroxicam, and it was established that differing resonance bands of the different forms could be used to discriminate between the different crystalline forms. 53 Reproducible methods for the preparation of three polymorphic forms of pyrazinamide have been reported, together with a full thermodynamic characterization of the relative stabilities and phase interconversion processes.…”