Structural characterization and dissolution profile of mycophenolic acid cocrystals

Physicochemical Characterization and In Vitro Activity of Poly(ε-Caprolactone)/Mycophenolic Acid Amorphous Solid Dispersions

The obtention of amorphous solid dispersions (ASDs) of mycophenolic acid (MPA) in poly(ε-caprolactone) (PCL) is reported in this paper. An improvement in the bioavailability of the drug is possible thanks to the favorable specific interactions occurring in this system. Differential scanning calorimetry (DSC) was used to investigate the miscibility of PCL/MPA blends, measuring glass transition temperature (Tg) and analyzing melting point depression to obtain a negative interaction parameter, which indicates the development of favorable inter-association interactions. Fourier transform infrared spectroscopy (FTIR) was used to analyze the specific interaction occurring in the blends. Drug release measurements showed that at least 70% of the drug was released by the third day in vitro in all compositions. Finally, preliminary in vitro cell culture experiments showed a decreased number of cancerous cells over the scaffolds containing MPA, presumably arising from the anti-cancer activity attributable to MPA.

Low-Frequency Raman Spectroscopy of Pure and Cocrystallized Mycophenolic Acid

The aqueous solubility of solid-state pharmaceuticals can often be enhanced by cocrystallization with a coformer to create a binary cocrystal with preferred physical properties. Greater understanding of the internal and external forces that dictate molecular structure and intermolecular packing arrangements enables more efficient design of new cocrystals. Low-frequency (sub-200 cm^-1) Raman spectroscopy experiments and solid-state density functional theory simulations have been utilized together to investigate the crystal lattice vibrations of mycophenolic acid, an immunosuppressive drug, in its pure form and as a cocrystal with 2,2'-dipyridylamine. The lattice vibrations primarily consist of large-amplitude translations and rotations of the crystal components, thereby providing insights into the critical intermolecular forces governing cohesion of the molecular solids. The simulations reveal that despite mycophenolic acid having a significantly unfavorable conformation in the cocrystal as compared to the pure solid, the cocrystal exhibits greater thermodynamic stability over a wide temperature range. The energetic penalty due to the conformational strain is more than compensated for by the strong intermolecular forces between the drug and 2,2'-dipyridylamine. Quantifying the balance of internal and external energy factors in cocrystal formation indicates a path forward in the development of future mycophenolic acid cocrystals.

Mechanochemistry: A Green Approach in the Preparation of Pharmaceutical Cocrystals

Mechanochemistry is considered an alternative attractive greener approach to prepare diverse molecular compounds and has become an important synthetic tool in different fields (e.g., physics, chemistry, and material science) since is considered an ecofriendly procedure that can be carried out under solvent free conditions or in the presence of minimal quantities of solvent (catalytic amounts). Being able to substitute, in many cases, classical solution reactions often requiring significant amounts of solvents. These sustainable methods have had an enormous impact on a great variety of chemistry fields, including catalysis, organic synthesis, metal complexes formation, preparation of multicomponent pharmaceutical solid forms, etc. In this sense, we are interested in highlighting the advantages of mechanochemical methods on the obtaining of pharmaceutical cocrystals. Hence, in this review, we describe and discuss the relevance of mechanochemical procedures in the formation of multicomponent solid forms focusing on pharmaceutical cocrystals. Additionally, at the end of this paper, we collect a chronological survey of the most representative scientific papers reporting the mechanochemical synthesis of cocrystals.

Mechanistic In Situ and Ex Situ Studies of Phase Transformations in Molecular Co-Crystals

Co-crystallisation is widely explored as a route to improve the physical properties of pharmaceutical active ingredients, but little is known about the fundamental mechanisms of the process. Herein, we apply a hyphenated differential scanning calorimetry-X-ray diffraction technique to mimic the commercial hot melt extrusion process, and explore the heat-induced synthesis of a series of new co-crystals containing isonicotinamide. These comprise a 1:1 co-crystal with 4-hydroxybenzoic acid, 2:1 and 1:2 systems with 4-hydroxyphenylacetic acid and a 1:1 crystal with 3,4-dihydroxyphenylactic acid. The formation of co-crystals during heating is complex mechanistically. In addition to co-crystallisation, conversions between polymorphs of the co-former starting materials and co-crystal products are also observed. A subsequent study exploring the use of inkjet printing and milling to generate co-crystals revealed that the synthetic approach has a major effect on the co-crystal species and polymorphs produced.

The first zwitterionic cocrystal of indomethacin with amino acid showing optimized physicochemical properties as well as accelerated absorption and slowed elimination in vivo

The first zwitterionic cocrystal of indomethacin (INC) with proline (PL) with optimized in vitro/in vivo properties was prepared and characterized.

Synthesis, Crystal Structure, and Solubility Analysis of a Famotidine Cocrystal

A novel cocrystal of the potent H2 receptor antagonist famotidine (FMT) was synthesized with malonic acid (MAL) to enhance its solubility. The cocrystal structure was characterized by X-ray single crystal diffraction, and the asymmetry unit contains one FMT and one MAL connected via intermolecular hydrogen bonds. The crystal structure is monoclinic with a P21/n space group and unit cell parameters a = 7.0748 (3) Å, b = 26.6502 (9) Å, c = 9.9823 (4) Å, α = 90, β = 104.2228 (12), γ = 90, V = 1824.42 (12) Å3, and Z = 4. The cocrystal had unique thermal, spectroscopic, and powder X-ray diffraction (PXRD) properties that differed from FMT. The solubility of the famotidine-malonic acid cocrystal (FMT-MAL) was 4.2-fold higher than FMT; the FAM-MAL had no change in FMT stability at high temperature, high humidity, or with illumination.

Co-crystallization of anti-inflammatory pharmaceutical contaminants and rare carboxylic acid–pyridine supramolecular synthon breakdown

Co-crystallization of the pharmaceutical contaminants mefenamic acid and naproxen is reported; one co-crystal exhibits a rare carboxylic acid–pyridine synthon breakdown.

Pharmaceutical cocrystals, salts and polymorphs: Advanced characterization techniques

The main goal of a novel drug development is to obtain it with optimal physiochemical, pharmaceutical and biological properties. Pharmaceutical companies and scientists modify active pharmaceutical ingredients (APIs), which often are cocrystals, salts or carefully selected polymorphs, to improve the properties of a parent drug. To find the best form of a drug, various advanced characterization methods should be used. In this review, we have described such analytical methods, dedicated to solid drug forms. Thus, diffraction, spectroscopic, thermal and also pharmaceutical characterization methods are discussed. They all are necessary to study a solid API in its intrinsic complexity from bulk down to the molecular level, gain information on its structure, properties, purity and possible transformations, and make the characterization efficient, comprehensive and complete. Furthermore, these methods can be used to monitor and investigate physical processes, involved in the drug development, in situ and in real time. The main aim of this paper is to gather information on the current advancements in the analytical methods and highlight their pharmaceutical relevance.