Novel Pharmaceutical Cocrystal Consisting of Chlorzoxazone and Nicotinamide: A New Promising Carrier for Solubility Augmentation

Chlorzoxazone (CHZ) is a centrally acting muscle relaxant used to treat muscle spasms. It is employed as a first-line medication for treating muscle spasms, offering both musculoskeletal relaxation and mild sedative effects. According to the biopharmaceutics classification system, it belongs to class II drug having poor solubility and high permeability. In order to improve the flow property, water solubility, and dissolution of CHZ, CHZ-nicotinamide (NA) cocrystal was prepared by liquid-assisted grinding cocrystallization (LAG CC) method using methanol as the choice of solvent. CHZ-NA cocrystal was characterized by differential scanning calorimeter (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared spectrometry, and scanning electron microscopy (SEM). DSC scan showed a sharp endothermic peak shift, which is caused by the formation of a new crystal form with altered physical properties, which was further confirmed by PXRD. Also, a change in the surface morphology of LAG CC compared to CHZ was observed in SEM. The resultant CHZ-NA cocrystal displayed improved powder flow properties compared to the native form of CHZ. LAG CC demonstrated a 3.1- and 2.6-fold increase in saturated solubility and intrinsic dissolution rate, respectively, compared to CHZ alone. Furthermore, the in vitro dissolution study showed that the cumulative dissolution of CHZ in 2 h was about 53%. Whereas, dissolution of LAG CC reached 99% in 2 h, showing obvious dissolution improvement. Thus, CHZ-NA cocrystal could significantly improve the flow properties, solubility and dissolution of CHZ.

Enhancing the Stability, Solubility, and Antioxidant Activity of Cinchonine through Pharmaceutical Cocrystallization

PURPOSE

Cinchoninze hydrochloride solves the problem of the low solubility of cinchonine, but it is unstable and susceptible to deliquescence. In this study, we designed and prepared cinchonine cocrystal salts or cinchonine salts with better stability, solubility and antioxidant activity than cinchonine.

METHOD

We successfully synthesized and characterized three cinchonine salts, namely, cinchonine-fumaric acid, cinchonine-isoferulic acid, and cinchonine-malic acid. The high humidity (92.5% RH) and high temperature (60°C) tests were conducted to determine the physical stability and hygroscopicity of cinchonine hydrochloride, cinchonine and three cinchonine salts. And the ultraviolet spectrophotometry was conducted to determine the equilibrium solubility and intrinsic dissolution rate of cinchonine and salts. Moreover, the DPPH, ABTS, and FRAP assays determined the antioxidant activity of cinchonine and salts.

RESULT

Compared with cinchonine hydrochloride and cinchonine, all three cinchonine salts exhibited good physical stability over 15 days under high humidity (92.5% RH) and high temperature (60°C) conditions. While cinchonine and cinchonine hydrochloride are categorized as hygroscopic and deliquescent, respectively, three cinchonine salts are classified as slightly hygroscopic, meaning that they have a lower hygroscopicity than cinchonine and cinchonine hydrochloride. And three cinchonine salts had higher equilibrium solubility, faster intrinsic dissolution rates, and higher antioxidant activity in comparison to cinchonine. Moreover, they showed a "spring and parachute" pattern in the phosphate buffer (pH = 6.8).

CONCLUSION

Cocrystallization technology is a viable option for improving cinchonine's poor physicochemical qualities.

New Hydrophilic Matrix Tablets for the Controlled Released of Chlorzoxazone

The modified release of active substances such as chlorzoxazone from matrix tablets, based on Kollidon®SR and chitosan, depends both on the drug solubility in the dissolution medium and on the matrix composition. The aim of this study is to obtain some new oral matrix tablet formulations, based on Kollidon®SR and chitosan, in order to optimize the low-dose oral bioavailability of chlorzoxazone, a non-steroidal anti-inflammatory drug of class II Biopharmaceutical Classification System. Nine types of chlorzoxazone matrix tablets were obtained using the direct compression method by varying the components ratio as 1:1, 1:2, and 1:3 chlorzoxazone/excipients, 20-40 w/w % Kollidon®SR, 3-7 w/w % chitosan while the auxiliary substances: Aerosil® 1 w/w %, magnesium stearate 0.5 w/w % and Avicel® up to 100 w/w % were kept in constant concentrations. Pharmaco-technical characterization of the tablets included the analysis of flowability and compressibility properties (flow time, friction coefficient, angle of repose, Hausner ratio, and Carr index), and pharmaco-chemical characteristics (such as mass and dose uniformity, thickness, diameter, mechanical strength, friability, softening degree, and in vitro release profiles). Based on the obtained results, only three matrix tablet formulations (F1b, F2b, and F3b, containing 30 w/w % KOL and 5 w/w % CHT, were selected and further tested. These formulations were studied in detail by Fourier-transform infrared spectrometry, X-ray diffraction, thermogravimetry, and differential scanning calorimetry. The three formulations were comparatively studied regarding the release kinetics of active substances using in vitro release testing. The results were analyzed by fitting into four representative mathematical models for the modified-release oral formulations. In vitro kinetic study revealed a complex mechanism of release occurring in two steps of drug release, the first step (0-2 h) and the second (2-36 h). Two factors were calculated to assess the release profile of chlorzoxazone: f1-the similarity factor, and f2-the factor difference. The results have shown that both Kollidon®SR and chitosan may be used as matrix-forming agents when combined with chlorzoxazone. The three formulations showed optima pharmaco-technical properties and in vitro kinetic behavior; therefore, they have tremendous potential to be used in oral pharmaceutical products for the controlled delivery of chlorzoxazone. In vitro dissolution tests revealed a faster drug release for the F2b sample.

Structural Landscape of α-Acetamidocinnamic Acid Cocrystals with Bipyridine-Based Coformers: Influence of Crystal Packing on Their Thermal and Photophysical Properties

Controlling the supramolecular synthon outcome in systems with different functionalities has been a key factor for the design of supramolecular materials, which also affected their physicochemical properties. In this contribution, we have analyzed the structural landscape of α-acetamidocinnamic acid (HACA) aiming to find its synthon outcome from the competitivity between its acidic and amidic groups. We prepared four multicomponent forms including one dihydrate (HACA·2H2O) and three cocrystals bearing different bipyridine coformers with formulas (HACA)2(1,2-bpe) (1), (HACA)2(4,4'-azpy) (2), and (HACA)2(4,4'-bipy)3 (3) (1,2-bpe = 1,2-bis(4-pyridyl)ethylene; 4,4'-azpy = 4,4'-azopyridine; 4,4'-bipy = 4,4'-bipyridine). First, we applied a virtual screening approach to assess the feasibility of cocrystal formation. Then, we synthesized the cocrystals, via liquid-assisted grinding (LAG) (1 and 2) or solvothermal (3) techniques, and single crystals of HACA, and their four multicomponent forms were obtained showing different synthons and crystal packings. Besides, a Cambridge Structural Database (CSD) search of the cocrystals presenting bipyridine-type coformers and molecules with acid and amide functionalities was performed, and the observed synthon occurrences as well as the possibility of synthon modification by tuning the H-donor/H-acceptor propensity of the acidic and amidic groups were shown. Finally, we measured their thermal and photophysical properties, which were correlated with their structural features.

Tuning Caco-2 permeability by cocrystallization: Insights from molecular dynamics simulation

Emerging evidence suggests that intestinal permeability can be potentially enhanced through cocrystallization. However, a mechanism for this effect remains to be established. In this study, we first demonstrate the enhancement in intestinal permeability, evaluated by the Caco-2 cell permeability assay, of acetazolamide (ACZ) in the presence of a conformer, p-aminobenzoic acid (PABA), delivered in the form of a 1:1 cocrystal. The binding strength of ACZ and PABA with the Pgp efflux transporter, either alone or as a mixture, was calculated using molecular dynamics simulation. Results show that PABA weakens the binding of ACZ with Pgp, which leads to a lower efflux ratio and elevated permeability of ACZ. This work provides molecular-level insights into a potentially effective strategy to improve the intestinal permeability of drugs. If the same cocrystal also exhibits higher solubility, oral bioavailability of BCS IV drugs can likely be improved by forming a cocrystal with a Pgp inhibitor.

Development of ezetimibe eutectic with improved biopharmaceutical and mechanical properties to design an optimized oral solid dosage formulation

Eutectics are multicomponent systems which are an alternative to the conventional techniques for modulating the biopharmaceutical properties of a pharmaceutical. Ezetimibe (ETZ) is a hypocholesterolemic agent with limited dissolution, poor water solubility, and subsequently demonstrates low oral bioavailability. Additionally, ETZ exhibits poor mechanical properties, leading to difficulties in developing dosage forms through direct compression. The present work highlights the applicability of eutectics in the simultaneous improvement of physicochemical along with mechanical properties of ETZ. A pharmaceutical eutectic of ETZ with succinimide (SUC) was prepared by mechanochemical grinding and thoroughly characterized using thermoanalytical, X-ray diffraction, and spectroscopic methods. Intrinsic dissolution rate and pharmacokinetic analysis were also performed for ezetimibe-succinimide (ETZ-SUC) eutectic in contrast to pure ETZ. The eutectic demonstrated ∼2-fold increase in the solubility and dissolution rate. In pharmacokinetic studies, the area under the curve (AUC) for ETZ-SUC eutectic (28.03 ± 2.22 ng*h/mL) was found to be higher than ETZ (8.98 ± 0.36 ng*h/mL), indicating improved oral bioavailability for eutectics. Also, it was observed that enhanced material functionality aids in designing directly compressed tablets, where the eutectic formulation showed an improved dissolution profile over the ETZ formulation. The study demonstrates that eutectic conglomerates could be utilized to develop ideal oral solid dosage formulations.

Gefitinib-resveratrol Cocrystal with Optimized Performance in Dissolution and Stability

Gefitinib (GEF) is an anti-tumor oral solid formulation with a superior advantage for lung tumors. However, it has poor aqueous solubility which limits its utility in vivo. Herein, a novel cocrystal (GEF-RES) assembled by GEF and RES (Resveratrol) has been successfully prepared and comprehensively characterized by differential scanning calorimetry, thermogravimetric analysis, Raman spectroscopy and powder X-ray diffraction. A single-crystal structure of the GEF-RES cocrystal was solved and illustrated in detail. In aqueous hydrochloric acid, the GEF-RES cocrystal showed that the maximum concentration of GEF was slightly higher than that of raw GEF. Furthermore, the thermal and physical stability of the GEF-RES cocrystal were also evaluated in this paper. The enhanced solubility and excellent solid-state stability results may provide new potential to the application of key GEF in clinical.

Systems Drug Discovery for Diffuse Large B Cell Lymphoma Based on Pathogenic Molecular Mechanism via Big Data Mining and Deep Learning Method

Diffuse large B cell lymphoma (DLBCL) is an aggressive heterogeneous disease. The most common subtypes of DLBCL include germinal center b-cell (GCB) type and activated b-cell (ABC) type. To learn more about the pathogenesis of two DLBCL subtypes (i.e., DLBCL ABC and DLBCL GCB), we firstly construct a candidate genome-wide genetic and epigenetic network (GWGEN) by big database mining. With the help of two DLBCL subtypes’ genome-wide microarray data, we identify their real GWGENs via system identification and model order selection approaches. Afterword, the core GWGENs of two DLBCL subtypes could be extracted from real GWGENs by principal network projection (PNP) method. By comparing core signaling pathways and investigating pathogenic mechanisms, we are able to identify pathogenic biomarkers as drug targets for DLBCL ABC and DLBCL GCD, respectively. Furthermore, we do drug discovery considering drug-target interaction ability, drug regulation ability, and drug toxicity. Among them, a deep neural network (DNN)-based drug-target interaction (DTI) model is trained in advance to predict potential drug candidates holding higher probability to interact with identified biomarkers. Consequently, two drug combinations are proposed to alleviate DLBCL ABC and DLBCL GCB, respectively.

Polymorphism in the 1/1 Pterostilbene/Picolinic Acid Cocrystal

The crystal structures of two new polymorphs of the 1/1 pterostilbene/picolinic acid cocrystal have been analyzed by single-crystal X-ray diffraction and studied by means of DFT calculations and a set of computational tools (QTAIM, NCIplot, MEP). The observation of a new R2 2(10) synthon in each of the two polymorphs has been analyzed energetically, characterized using the topology of the electron density, and rationalized using the MEP surfaces. The exceptional bioavailability of the cocrystal is explained on the basis of BFDH morphology calculations, and the study is complemented by a deep analysis of the supramolecular synthons formed by both neutral and zwitterionic forms of picolinic acid, a versatile coformer for crystal engineering.

Pharmaceutical cocrystals: A review of preparations, physicochemical properties and applications

Pharmaceutical cocrystals are multicomponent systems in which at least one component is an active pharmaceutical ingredient and the others are pharmaceutically acceptable ingredients. Cocrystallization of a drug substance with a coformer is a promising and emerging approach to improve the performance of pharmaceuticals, such as solubility, dissolution profile, pharmacokinetics and stability. This review article presents a comprehensive overview of pharmaceutical cocrystals, including preparation methods, physicochemical properties, and applications. Furthermore, some examples of drug cocrystals are highlighted to illustrate the effect of crystal structures on the various aspects of active pharmaceutical ingredients, such as physical stability, chemical stability, mechanical properties, optical properties, bioavailability, sustained release and therapeutic effect. This review will provide guidance for more efficient design and manufacture of pharmaceutical cocrystals with desired physicochemical properties and applications.

Supramolecular self-assembly of amantadine hydrochloride with ferulic acid via dual optimization strategy establishes a precedent of synergistic antiviral drug-phenolic acid nutraceutical cocrystal

To display the capability of the phenolic acid nutraceutical ferulic acid (FLA) in optimizing the in vitro/in vivo properties of the antiviral drug amantadine hydrochloride (AMH) and achieve synergistically enhanced antiviral effects, thereby gaining some new insights into pharmaceutical cocrystals of antiviral drugs with phenolic acid nutraceuticals, a cocrystallization strategy of dual optimization was created. Based on this strategy, the first drug-phenolic acid nutraceutical cocrystal of AMH with FLA, namely AMH-FLA-H2O, was successfully assembled and completely characterized by employing single-crystal X-ray diffraction and other analytical techniques. The cocrystal was revealed to be composed of AMH, FLA, and water molecules in the ratio of 3 : 1 : 1.5, and charge-assisted hydrogen bonds containing chloride ions crucially maintained the crystal lattice together with water molecules. The in vitro/in vivo properties of the cocrystal were systematically evaluated via both theoretical and experimental methods, and the results indicate that the dissolubility of AMH is down-regulated by two-thirds in the cocrystal, resulting in its potential for sustained pharmacokinetic release and the elimination of the adverse effects of AMH. More importantly, the enhanced antiviral effects of the current cocrystal were proven against four viral strains, and the pharmaceutical synergy between AMH and FLA was realized with a combination index (CI) of less than 1. Thus, the present work provides a novel crystalline product with bright commercial prospect for the classical antiviral drug AMH and also establishes an avenue for the synergetic antiviral application of nutraceutical phenolic acids via the cocrystallization strategy of dual optimization.

Cocrystals Based on 4,4’-bipyridine: Influence of Crystal Packing on Melting Point

The reactions of piperonylic acid (HPip) and cinnamic acid (HCinn) with 4,4’-bipyridine (4,4’-bipy) have been assayed using the same synthetic methodology, yielding two binary cocrystals with different acid:4,4’-bipy molar ratios, (HPip)(4,4’-bipy) (1) and (HCinn)2(4,4’-bipy) (2). The melting point (m.p.) of these cocrystals have been measured and a remarkable difference (ΔT ≈ 78 °C) between them was observed. Moreover, the two cocrystals have been characterized by powder X-ray diffraction (PXRD), elemental analysis (EA), FTIR-ATR, 1H NMR spectroscopies, and single-crystal X-ray diffraction. The study of their structural packings via Hirshfeld surface analysis and energy frameworks revealed the important contribution of the π···π and C-H···π interactions to the formation of different structural packing motifs, this being the main reason for the difference of m.p. between them. Moreover, it has been observed that 1 and 2 presented the same packing motifs as the crystal structure of their corresponding carboxylic acids, but 1 and 2 showed lower m.p. than those of the carboxylic acids, which could be related to the lower strength of the acid-pyridine heterosynthons respect to the acid-acid homosynthons in the crystal structures.

Novel Purine Alkaloid Cocrystals with Trimesic and Hemimellitic Acids as Coformers: Synthetic Approach and Supramolecular Analysis

In this work, benzene-1,3,5-tricarboxylic (trimesic acid, TMSA) and benzene-1,2,3-tricarboxylic acid (hemimellitic acid, HMLA) were used as coformers for cocrystal synthesis with chosen purine alkaloids. Theobromine (TBR) forms cocrystals TBR·TMSA and TBR·HMLA with these acids. Theophylline (TPH) forms cocrystals TPH·TMSA and TPH·HMLA, the cocrystal hydrate TPH·TMSA·2H₂O and the salt hydrate (TPH)⁺·(HMLA)^-·2H₂O. Caffeine (CAF) forms the cocrystal CAF·TMSA and the cocrystal hydrate CAF·HMLA·H₂O. The purine alkaloid derivatives were obtained by solution crystallization and by neat or liquid-assisted grinding. The powder X-ray diffraction method was used to confirm the synthesis of the novel substances. All of these solids were structurally characterized, and all synthons formed by purine alkaloids and carboxylic acids were recognized using a single-crystal X-ray diffraction method. The Cambridge Structural Database was used to determine the frequency of occurrence of analyzed supramolecular synthons, which is essential at the crystal structure design stage. Determining the influence of structural causes on the various synthon formations and molecular arrangements in the crystal lattice was possible using structurally similar purine alkaloids and two isomers of benzenetricarboxylic acid. Additionally, UV-vis measurements were made to determine the effect of cocrystallization on purine alkaloid solubility.

Progress on cocrystallization of poorly soluble NME's in the last decade

Cocrystallization of pharmaceuticals has been an exciting field of interest to both academia and industries, demonstrated from its increasing growth rate of publications, patents, and marketed formulations.