Simultaneous Improvement of Dissolution Behavior and Oral Bioavailability of Antifungal Miconazole via Cocrystal and Salt Formation

Miconazole shows low oral bioavailability in humans due to poor aqueous solubility, although it has demonstrated various pharmacological activities such as antifungal, anti-tubercular and anti-tumor effects. Cocrystal/salt formation is one of the effective methods for solving this problem. In this study, different methods (liquid-assisted grinding, slurrying and lyophilization) were used to investigate their impact on the formation of the miconazole multicomponent crystals with succinic, maleic and dl-tartaric acids. The solid state of the prepared powder was characterized by differential scanning calorimetry, powder X-ray diffraction and scanning electron microscopy. It was found that lyophilization not only promotes partial amorphization of both salts but also allows obtaining a new polymorph of the miconazole salt with dl-tartaric acid. The lyophilized salts compared with the same samples prepared by two other methods showed better dissolution rates but low stability during the studies due to rapid recrystallization. Overall, it was determined that the preparation method of multicomponent crystals affects the solid-state characteristics and miconazole physicochemical properties significantly. The in vivo studies revealed that the miconazole multicomponent crystals indicated the higher peak blood concentration and area under the curve from 0 to 32 h values 2.4-, 2.9- and 4.6-fold higher than the pure drug. Therefore, this study demonstrated that multicomponent crystals are promising formulations for enhancing the oral bioavailability of poorly soluble compounds.

Cocrystallization-driven self-assembly with vanillic acid offers a new opportunity for surmounting fast and excessive absorption issues of antifungal drug 5-fluorocytosine: a combined theoretical and experimental research

The cocrystal of 5-fluorocytosine (FCY) with vanillic acid (VAA) was assembled via a cocrystallization technique, giving a novel understanding for conquering the dose-limited hepatotoxicity caused by the rapid and almost complete absorption of FCY.

Polymorphic forms of antiandrogenic drug nilutamide: structural and thermodynamic aspects

Attempts to obtain new cocrystals of nonsteroidal antiandrogenic drug nilutamide produced alternative polymorphic forms of the compound (Form II and Form III) and their crystal structures were elucidated by single-crystal X-ray diffraction. Apart from the cocrystallization technique, lyophilization was found to be an effective strategy for achieving polymorph control of nilutamide, which was difficult to obtain by other methods. The physicochemical properties and relative stability of the commercial Form I and newly obtained Form II were comprehensively investigated by a variety of analytical methods (thermal analysis, solution calorimetry, solubility, and sublimation), whereas for Form III, only a handful of experimental parameters were obtained due to the elusive nature of the polymorph. Form I and Form II were found to be monotropically related, with Form I being confirmed as the thermodynamically most stable solid phase. In addition, the performance of different DFT-D and semi-empirical schemes for lattice energy calculation and polymorph energy ranking was compared and analysed. Lattice energy calculations using periodic DFT at B3LYP-D3/6-31(F+)G(d,p) and PBEh-3c/def2-mSVP levels of theory were found to provide the most accurate lattice energy values for Form I against experimental data, while PIXEL and PBEh-3c/def2-mSVP were the only methods that predicted the correct order of stability of Forms I and II.

Hydrates of adenosine 3′,5′-cyclic monophosphate sodium and their transformation

The difference of crystal water behaviors for cAMPNa hydrates was attributed mainly to the steric effects in lattices. Excessive loss of crystal water would destroy the host structure, and result in the disability of reversible transformation.

Crystal structure and Hirshfeld surface analysis of 2-amino-3-hy-droxy-pyridin-1-ium 6-methyl-2,2,4-trioxo-2H,4H-1,2,3-oxa-thia-zin-3-ide

The asymmetric unit of the title compound, C5H7N2O+·C4H4NO4S-, contains one cation and one anion. The 6-methyl-2,2,4-trioxo-2H,4H-1,2,3-oxa-thia-zin-3-ide anion adopts an envelope conformation with the S atom as the flap. In the crystal, the anions and cations are held together by N-H⋯O, N-H⋯N, O-H⋯O and C-H⋯O hydrogen bonds, thus forming a three-dimensional structure. The Hirshfeld surface analysis and fingerprint plots reveal that the crystal packing is dominated by O⋯H/H⋯O (43.1%) and H⋯H (24.2%) contacts.

Supramolecular synthesis and characterization of crystalline solids obtained from the reaction of 5-fluorocytosine with nitro compounds

In this manuscript we introduce a broad solid-state characterization of 5-fluorocytosine (5-FC) solid forms obtained with picric (PA) and 3,5-dinitrosalicylic (DNSA) nitro acids.

Piroxicam–clonixin drug–drug cocrystal solvates with enhanced hydration stability

Piroxicam and clonixin can form drug–drug crystalline complexes with the help of suitable solvent molecules.

Crystal structure of 4,4′-(1,4-phenylene)bis(1H-imidazol-3-ium)bis(2-carboxybenzoate), C30H26N4O8

C30H26N4O8, monoclinic, P21/n (no. 14), a = 6.6363(7) Å, b = 9.0231(9) Å, c = 22.082(2) Å, β = 92.765(2)°, V =1320.7(2) Å3, Z = 2, R gt(F) = 0.0455, wR ref(F 2) = 0.1234, T = 296(2) K.

Avoiding irreversible 5-fluorocytosine hydration via supramolecular synthesis of pharmaceutical cocrystals

Supramolecular reaction of 5-FC with caffeine, p-aminobenzoic and caprylic acid gave rise to solid forms physically stable in humid environments.

Cocrystals of zileuton with enhanced physical stability

Zileuton can form two promising pharmaceutical cocrystals with nicotinamide and isonicotinamide, which demonstrate superior phase stability against moisture.

Synthesis of cocrystals/salts of flucytosine: Structure and stability

Three molecular salts and two cocrystals of FLC were synthesized with superior solid state stability.

Structural investigation of the cocrystal formed between 5-fluorocytosine and fumaric acid based on vibrational spectroscopic technique

The vibrational spectra of 5-fluorocytosine, fumaric acid and their cocrystal were measured using terahertz time-domain spectroscopy (THz-TDS) and Raman spectroscopy at room temperature. Experimental THz results show that the cocrystal has distinct fingerprint spectra in terahertz region. The absorption peaks observed in the terahertz spectra of the cocrystal were at 0.61 and 0.91THz. These are quite different from corresponding raw starting materials. Raman spectra also show similar results about differences between the cocrystal and corresponding raw starting materials. Density functional theory (DFT) was used to simulate the structure of the possible salt form and the cocrystal form between 5-fluorocytosine and fumaric acid. The theoretical terahertz result shows that the cocrystal form has absorption at 0.62 and 0.87THz, which is in agreement with the experimental result. The theoretical Raman result also indicates that the cocrystal form has more possibilities than the salt form. So, it is more reasonable that the structure between 5-fluorocytosine and fumaric acid could be the corresponding cocrystal form. The characteristic bands of the cocrystal between 5-fluorocytosine and fumaric acid are also assigned based on the simulation results from the DFT calculation.

Pharmaceutical crystalline complexes of sulfamethazine with saccharin: same interaction site but different ionization states

Sulfamethazine (SMT) can form either 1 : 1 salt or 1 : 1 cocrystal with saccharin (SAC). The two crystalline complexes possess the same main intermolecular interaction site except the locations of the acidic proton are different.

Insight into a direct solid–solid transformation: a potential approach for the removal of residual solvents

A simple humidity process allows a direct solid–solid transformation from the solvate (methanol trihydrate of cAMPNa) to its hydrate form (pentahydrate).