THEOPHYLLINE–NA–SACHARRINE SINGLE CRYSTAL ISOLATION FOR ITS STRUCTURE DETERMINATION

Objective: Co-crystal is a crystal form which consists of two or more components in a specific stoichiometric ratio. Theophylline has been reported to form a co-crystal with sodium saccharin, but its single-crystal has not been isolated, so its structure also has not been known yet. This research aimed to isolate the theophylline-sodium saccharin co-crystal with several solvent, studied its single-crystal structure, and observed the stability of the co-crystal formed in a high humidity. Methods: Theophylline anhydrous powder (TA), sodium saccharin dihydrate (NSD), and the physical mixtures of TA-NSD were characterized using a polarizing microscope, Fourier-Transform Infrared Spectroscopy (FTIR), Powder X-ray Diffractometer (PXRD), and Karl Fischer Titration (KFT); respectively. The single TA-NSD co-crystal formation was done by slow evaporation at ambient temperature (25 °C) and 12 °C, using four types of solvent mixtures, such as: water-isopropanol; water-acetone; ethanol-dichloromethane; and ethanol. The rate formations of co-crystals were observed and characterized using polarizing microscopy, FTIR, PXRD. The isolated co-crystal was analyzed using a Single-crystal X-Ray Diffractometer (SC-XRD). Finally; stability test was applied to TA-NSD co-crystal at an RH 95% chamber. Results: Single-crystals at most formed in water-isopropanol (1:7), with the size of 0.6 to 1.2 cm (at ambient temperature) and 0.6 to 1 cm (at 12 °C) and solvent of water-acetone 1: 9 with a size of 0.5 to 1.1 cm (at ambient temperature/25 °C). Meanwhile from the other solvents, co-crystal just was produced in the crystalline form; and thin crystals with a size of ≤ 5 mm both in ambient temperature and 12 °C. Visual observations that were supported by polarizing microscope magnification showed TA-NSD co-crystal has rod-shaped and translucent color. FTIR spectra analysis results showed N-H stretching of the co-crystal shift from a wavenumber 3124.12 to 3129.7-3131.83 cm-1. The diffractogram from PXRD analysis indicated that TA-NSD co-crystal has sharp peaks on 2Ɵ = 5.58, 12.32, 17.48, 22.40, 26.86, 27.4, 28.84, and 34.1 °. The SC-XRD result showed the TA-NSD co-crystal has monoclinic crystal system, which has not been reported previously. The stability test in high humidity proved that the co-crystal shows unchanged shift N-H strain, which means that TA-NSD co-crystal is stable. Conclusion: Based on all data, it is concluded that TA-NSD co-crystal has rod-shaped with translucent color, and has a monoclinic crystal system with volume 1583.9 (7) Å3. The single-crystals yielded from the water-isopropanol solvent system at ambient temperature and 12 °C; while from water-acetone 1: 9 was formed at 12 °C. The stability test in an RH 95% chamber showed that TA-NSD co-crystal is stable against the moisture

Solubility Improvement of Benexate through Salt Formation Using Artificial Sweetener

Benexate, a drug used clinically as a defensive type anti-ulcer agent, has poor solubility and a bitter taste. To improve its solubility, a crystal engineering approach was proposed with the formation of novel salts using an artificial sweetener as a salt co-former. This was also expected to address the bitter taste of the drug. In this work, we report on the preparation and evaluation of the physicochemical properties of the novel salts benexate saccharinate monohydrate and benexate cyclamate whose crystal structures were determined by single-crystal X-ray structure analysis. These novel salts showed higher solubility and faster dissolution profiles that were associated with the occurrence of local layered-like structures. They also showed better moisture uptake profiles and were classified as non-hygroscopic materials. Therefore, benexate saccharinate monohydrate and benexate cyclamate expedited the development of sweet pharmaceutical salts of benexate with improved performances

A peculiar dehydration and solid–solid phase transition of the active pharmaceutical ingredient AZD9898 based on <i>in situ</i> single crystal-to-single crystal transformations

AZD9898 has previously been used as a candidate for a potentially active pharmaceutical ingredient. AZD9898 form A hydrate was discovered during development and this form undergoes dehydration upon heating to give anhydrous form B. Further heating results in a solid–solid phase transition to a new anhydrous phase, form C. This study reports the crystal structures of form A, B, and C obtained by heating the single crystal of form A in situ on the diffractometer which establish the dehydration and solid–solid phase transition mechanisms. The dehydration from form A hydrate to form B anhydrous is an isostructural process while the solid–solid phase transition from form B to form C requires major structural changes. The relevant thermal profiles and vapour sorption behaviour of these forms are also reported in this study

Epalrestat tetrahydrofuran monosolvate: crystal structure and phase transition

The title compound, epalrestat {systematic name: (5Z)-5-[(2E)-2-methyl-3-phenylprop-2-en-1-ylidene]-4-oxo-2-sulfanylidene-1,3-thiazolidine-3-acetic acid}, crystallized as a tetrahydrofuran monosolvate, C15H13NO3S2·C4H8O. Epalrestat, an important drug for diabetic neuropathy, has been reported to exist in polymphic, solvated and co-crystal forms. In the molecule reported here, the phenyl ring is inclined to the rhodamine ring by 22.31 (9)°, and the acetic acid group is almost normal to the rhodamine ring, making a dihedral angle of 88.66 (11)°. In the crystal, pairs of O—H...O hydrogen bonds are observed between the carboxylic acid groups of epalerstat molecules, forming inversion dimers with an R22(8) loop. The dimers are linked by pairs of C—H...O hydrogen bonds, forming chains along [101]. The solvate molecules are linked to the chain by a C—H...O(tetrahydrofuran) hydrogen bond. A combination of thermal analysis and powder X-ray diffraction revealed that title compound desolvated into epalerstat Form II. One C atom of the tetrahydrofuran solvate molecule is positionally disordered and has a refined occupancy ratio of 0.527 (18):0.473 (18)