Multicomponent solid forms of the uric acid reabsorption inhibitor lesinurad and cocrystal polymorphs with urea: DFT simulation and solubility study

Polymorphs and Isostructural Cocrystals of Dexamethasone: Towards the improvement of aqueous solubility

Dexamethasone (DEX) is a corticosteroid drug used to treat arthritis, asthma, and considered as a promising drug for the treatment of Covid-19. The major drawback of DEX is its poor...

Isostructural cocrystals of metaxalone with improved dissolution characteristics

Muscle relaxant and pain reliever metaxalone (MET) is a biopharmaceutical classification systems (BCS) class II drug with poor aqueous solubility and high permeability. The presence of an aromatic skeleton and cyclic carboxamate moiety are the probable reasons for the decreased aqueous solubility, which impacts on its low bioavailability. A high dose (800 mg) of the drug often creates adverse side effects on the central nervous system that needs urgent remedy. Cocrystallization of MET with nicotinamide (NAM), salicylamide (SAM), and 4-hydroxybenzoic acid (HBA) resulted in multicomponent solids that were characterized by PXRD, DSC and single crystal X-ray diffraction. Cocrystals with SAM and NAM form 2D isostructural cocrystals, whereas with HBA the result is a differently packed cocrystal hydrate (or anisole hemisolvate) depending upon the crystallization medium. Similar to the reported MET cocrystals, these cocrystals also confirm the preference for an imide⋯imide homosynthon in the drug. The dominance of the drug–drug homodimer over drug-coformer heterodimers was demonstrated based on binding energy calculations. Further, powder dissolution experiments in pH 6.8 phosphate buffer indicate that the cocrystals improved the apparent solubility compared to the native drug by 3–9 fold. The absence of stronger heterosynthons between MET and the coformers, their lower melting points and the high solubility of the coformers are the probable reasons for the enhanced solubility of the bioactive component. The MET–NAM cocrystal exhibited the highest solubility/dissolution rate among the three binary solid forms, which may offer improved bioavailability and a lower dose with minimal side effects.

Metaxalone forms isostructural cocrystals with nicotinamide and salicylamide that offer a solubility advantage compared to the native drug. A drug–drug homosynthon is retained in all the cocrystal structures.

Preparation and Characterization of Solid Dispersions Composed of Curcumin, Hydroxypropyl Cellulose and/or Sodium Dodecyl Sulfate by Grinding with Vibrational Ball Milling

Solubility is an important physicochemical property affecting drug bioavailability. One approach to improve drug solubility is using amorphous formulations, which can improve solubility by up to a 1000-fold. Herein, amorphous curcumin (CUR) and amorphous solid dispersions (SDs) consisting of CUR, hydroxypropyl cellulose (HPC) and/or sodium dodecyl sulfate (SDS) were developed using vibrational ball milling. The resulting ground mixtures (GMs) were characterized using powder X-ray diffractometry, Fourier transform infrared spectroscopy, differential scanning calorimetry and a dissolution test. The 60-min GM containing 90% HPC significantly increased the drug solubility. Presence of SDS in the GMs containing 90% HPC reduced the grinding duration from 60 min to 30 min in forming a ground SD that significantly increased the CUR dissolution rate. This amorphous state was stable for 30 days when stored at 40 °C/RH 75%.

Spectroscopic Methodology and Molecular Docking Studies on Changes in Binding Interaction of Felodipine with Bovine Serum Albumin Induced by Cocrystallization with β-Resorcylic Acid

In the present study, a novel cocrystal of felodipine (FEL) and β-resorcylic acid (βRA) was developed. We specially focused on the change of binding pattern with bovine serum albumin (BSA) induced by cocrystallization of FEL with βRA. The solid characterizations and density functional theory (DFT) simulation verified that FEL-βRA cocrystal formed in equimolar ratio (1 : 1 M ratio) through C=O^…H-O hydrogen bond between C=O group in FEL and O-H group in βRA. The binding interactions between FEL-βRA system and BSA were studied using fluorescence spectral and molecular docking methods. Two guest molecule systems, including a physical mixture of FEL and βRA and FEL-βRA cocrystal were performed binding to BSA in molecular docking. According to the K_b and binding energy, the supramolecular form of FEL-βRA system was retained during binding to BSA. Molecular docking simulation suggested that FEL and its cocrystal inserted into the subdomain IIIA (site II') of BSA. The interactions between FEL and BSA including hydrogen bonding with ASN390 residue and intermolecular hydrophobic interactions with LEU429 and LEU452 residues. However, the size of supramolecular FEL-βRA better matched that of active cavity of BSA; the cocrystal is closely bound to BSA through hydrogen bonding with ASN390 residue and intermolecular hydrophobic interactions with LEU429, VAL432, LEU452 and ILE387 residues. This change on binding affinity of FEL to BSA induced by cocrystallization with βRA provided theoretical basis to evaluate the transportation, distribution and metabolism of cocrystal drug.

Structural variety of heterosynthons in linezolid cocrystals with modified thermal properties

In a search for new crystalline forms of linezolid with modified thermal properties five cocrystals of this wide range antibiotic with aromatic acids were obtained via mechanochemical grinding and analyzed with single crystal X-ray diffraction, solid-state NMR spectroscopy, powder X-ray diffraction and DSC measurements. The coformers used in this study were benzoic acid, p-hydroxybenzoic acid, protocatechuic acid, γ-resorcylic acid and gallic acid. In each of the cocrystals distinct structural features have been found, including a variable amount of water and different heterosynthons, indicating that there is more than one type of intermolecular interaction preferred by the linezolid molecule. Basing on the frequency of the observed supramolecular synthons, the proposed hierarchy of the hydrogen-bond acceptor sites of linezolid (LIN) is C=O_amide > C=O_oxazolidone > C-O-C_morpholine > C-N-C_morpholine > C-O-C_oxazolidone. In addition, aromatic-aromatic interactions were found to be important in the stabilization of the analyzed structures. The obtained cocrystals show modified thermal properties, with four of them having melting points lower than the temperature of the phase transition from linezolid form II to linezolid form III. Such a change in this physicochemical property allows for the future application of melting-based techniques of introducing linezolid into drug delivery systems. In addition a change in water solubility of linezolid upon cocrystalization was evaluated, but only in the case of the cocrystal with protocatechuic acid was there a significant (43%) improvement in solubility in comparison with linezolid.

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.