On the entropy cost of making solvates

Efficient Screening of Coformers for Active Pharmaceutical Ingredient Cocrystallization

Controlling the physical properties of solid forms for active pharmaceutical ingredients (APIs) through cocrystallization is an important part of drug product development. However, it is difficult to know a priori which coformers will form cocrystals with a given API, and the current state-of-the-art for cocrystal discovery involves an expensive, time-consuming, and, at the early stages of pharmaceutical development, API material-limited experimental screen. We propose a systematic, high-throughput computational approach primarily aimed at identifying API/coformer pairs that are unlikely to lead to experimentally observable cocrystals and can therefore be eliminated with only a brief experimental check, from any experimental investigation. On the basis of a well-established crystal structure prediction (CSP) methodology, the proposed approach derives its efficiency by not requiring any expensive quantum mechanical calculations beyond those already performed for the CSP investigation of the neat API itself. The approach and assumptions are tested through a computational investigation on 30 potential 1:1 multicomponent systems (cocrystals and solvate) involving 3 active pharmaceutical ingredients and 9 coformers and one solvent. This is complemented with a detailed experimental investigation of all 30 pairs, which led to the discovery of five new cocrystals (three API-coformer combinations, a polymorphic cocrystal example, and one with different stoichiometries) and a cis-aconitic acid polymorph. The computational approach indicates that, for some APIs, a significant proportion of all potential API/coformer pairs could be investigated with only a brief experimental check, thereby saving considerable experimental effort.

Structural studies of various olmesartan solvates

Seven solvates of the angiotensin II receptor blocker agent olmesartan (C24H26N6O3), namely, the methanol (C24H26N6O3·CH4O), ethanol (C24H26N6O3·C2H6O), isopropanol (C24H26N6O3·C3H8O), isobutanol (C24H26N6O3·C4H10O), 2-ethoxyethanol (C24H26N6O3·C4H10O2), chloroform (C24H26N6O3·CHCl3) and acetonitrile (C24H26N6O3·C2H3N) solvates, were successfully obtained. The crystal structures were determined using the single-crystal X-ray diffraction technique and the structural features are described, each solvate containing one molecule of olmesartan and one of solvent in the asymmetric unit. The samples were also analyzed by powder X-ray diffraction. Total lattice energies and binding energies between the olmesartan and solvent molecules were evaluated, which can be partitioned into electrostatic, polarization, dispersion and repulsion components. Hirshfeld and fingerprint plot analysis was performed to highlight the intermolecular contacts. Hydrogen bonding and supramolecular arrangements were comparatively studied for the seven solvates.

Understanding the thermal stability of apalutamide crystalline solvates through crystal structure analyses and computational studies

The conformational flexibility of APA molecules leads to different crystal packing. The stability of the solvent molecules in the crystal structures was established through their strong intermolecular interactions with the host molecule.

Insight into amoxicillin sodium heterosolvates and non-solvated form: crystal structures, phase transformation behaviors, and desolvation mechanism

Methanol and methyl acetate molecules played different roles in the formation of S_M–M amoxicillin sodium heterosolvate. A two-step desolvation mechanism of novel heterosolvates was proposed.

Organic solvates in the Cambridge Structural Database

Data informatics methods applied to the Cambridge Structural Database reveal shifting trends in solvate formation and inherent biases in the symmetry and packing fraction of solvates and their solvent-free analogues.

Systematic coformer contribution to cocrystal stabilization: energy and packing trends

CSD data mining and energy calculations show that coformer self-interactions might significantly contribute to the packing energy stabilization of cocrystals.

The formation mechanism of hollow spherulites and molecular conformation of curcumin and solvate

In this study, curcumin 1,4-dioxane solvates (CUR–DIO) were obtained in two molecular ratios of 1 : 1.5 (CUR–DIO-1.5) and 1 : 1 (CUR–DIO-1) at different temperatures.

Can solvated intermediates inform us about nucleation pathways? The case of β-pABA

Using crystallography to search for nucleation pathways: α and β polymorphs of p-aminobenzoic acid.