Experimental cocrystal screening and solution based scale-up cocrystallization methods

Surface Defects and Crystal Growth of Apremilast Benzoic Acid Cocrystals

A cocrystallization process of the active pharmaceutical ingredient apremilast with benzoic acid is explored in this work. The aim of the study is to adjust operating conditions during the crystallization to purposefully tune the dissolution properties of the final product. Understanding the cocrystallization is key to obtaining a consistent, high-quality product, as well as tuning other properties such as powder flowability or dissolution properties. It was discovered early in development that the studied cocrystallization process does not follow the common rules of crystallization. Better crystals were obtained at faster cooling rates and worse crystals at slower cooling rates. Interestingly, this can be explained by crystal collisions and a two-phase growth of the crystals. Standard operating conditions were further tested, resulting in different shapes and sizes of the product. Different types of produced crystals were tested in a dissolution apparatus and provided significantly modified dissolution profiles.

Co-crystallization in Antiepileptic Drugs: A Path Toward Better Therapeutic Outcomes

Pharmaceutical cocrystals are highly valued in drug development as they can enhance active pharmaceutical ingredients (APIs)' physicochemical characteristics without changing their chemical structure. This is especially important for biopharmaceutical classification system (BCS) class II and IV drugs, which have poor water solubility, resulting in low bioavailability. Co-crystallization is the process of forming a crystalline solid where the API and a co-former are combined in a specified stoichiometric proportion within a crystal lattice, mainly stabilized by non-covalent interactions. This method can enhance properties like stability, dissolution rate, solubility, compressibility, and powder flowability and pharmacokinetics, resulting in an improved drug delivery system and therapeutic effectiveness. Pharmaceutical antiepileptic drugs (AEDs) are the main focus of this review. Pharmaceutical characteristics, conventional and advanced cocrystal generation, and assessment techniques, as well as recent developments related to cocrystals, may suggest perception for cocrystal potential, design approaches, and regulatory aspects. The study's overall finding emphasizes the growth of co-crystallization as a significant technique to enhance the drug's performance and also demonstrates its potential as a significant technique in the AED category and its future application.

Pharmaceutical Salts: Comprehensive Insights From Fundamental Chemistry to FDA Approvals (2019-2023)

Pharmaceutical salts are a cornerstone in drug development, offering a robust, economical, and industry-friendly option for improving the crucial physicochemical properties of drugs, particularly solubility and dissolution. This review article explores all critical aspects of salt formation, including its importance, the basic chemistry involved, the principles governing counterion selection, the range of counterions used, and the methods for preparing salts along with their advantages and limitations. Additionally, it explores analytical techniques for confirming salt formation and the different approaches various countries adopt in considering new salts as intellectual property. Furthermore, the review sheds light on US FDA-approved salts from 2019 to 2023, providing a unique perspective by analyzing trends in counterion selection observed in FDA-approved salts during this period. Despite the extensive literature on pharmaceutical salts, a comprehensive review addressing all these critical aspects in a single article with a focus on current trends and particularly on US FDA-approved salts from 2019 to 2023 is lacking. This review bridges this gap by thoroughly exploring all mentioned facets of pharmaceutical salts and providing an up-to-date overview.

Cocrystal screening in minutes by solution-mediated phase transformation (SMPT): Preparation and characterization of ketoconazole cocrystals with nine aliphatic dicarboxylic acids

The rapid and efficient cocrystal screening, based on solution-mediated phase transformation (SMPT), was applied to the screening of cocrystals between ketoconazole (KTZ) and nine aliphatic dicarboxylic acids. Cocrystals formed successfully, in minutes, with a change of suspension characteristics, either a cake formation or the formation of large particles. Bulk cocrystals were characterized by powder X-ray diffraction, thermal analysis, and Raman spectroscopy. Single crystals were grown, and molecular structures were determined. Three previously reported cocrystals were reproduced, and six new cocrystals were discovered, including one that was reported as a failure in literature by solution or grinding method. Two hydrogen-bonded motifs are observed in these nine cocrystals: Most cocrystals form hydrogen bonded discrete tetramer with two KTZ and two acids molecules; while two cocrystals form infinite chain. This study demonstrated the high efficacy of cocrystal generation using the slurry screening method. It should be fully utilized in future cocrystal screening.

Evaluating experimental, knowledge-based and computational cocrystal screening methods to advance drug-drug cocrystal fixed-dose combination development

Fixed-dose combinations (FDCs) offer significant advantages to patients and the pharmaceutical industry alike through improved dissolution profiles, synergistic effects and extended patent lifetimes. Identifying whether two active pharmaceutical ingredients have the potential to form a drug-drug cocrystal (DDC) or interact is an essential step in determining the most suitable type of FDC to formulate. The lack of coherent strategies to determine if two active pharmaceutical ingredients that can be co-administered can form a cocrystal, has significantly impacted DDC commercialisation. This review aims to accelerate the development of FDCs and DDCs by evaluating existing experimental, knowledge-based and computational cocrystal screening methods; the background of their development, their application in screening for cocrystals and DDCs, and their limitations are discussed. The evaluation provided in this review will act as a guide for selecting suitable screening methods to accelerate FDC development.

A quality by design strategy for cocrystal design based on novel computational and experimental screening strategies: part A

While pharmaceutical Cocrystals have long been acknowledged as a promising method of enhancing a drugs bioavailability, they have not yet experienced widespread industrial adoption on the same scale as other multi-component drugs, such as salts and amorphous solid dispersions. This is partly due to the lack of a being no definitive screening strategy to identify suitable coformers, with the most cocrystal screening strategies heavily relying on trial and error approaches, or through utilizing a multiple and often conflicting, computational screening techniques combined with high material consumption experimental techniques. From the perspective of industry, this can often lead to high material waste and increased costs, encouraging the prioritization of more traditional bioenhancement techniques. Here we present a strategy for the selection of multicomponent systems involving computational modelling for screening of drug- former pairs based on a combination of molecular complementarity and H-bond propensity screening. Jet dispensing printing technology is co-opted as a mechanism for High-Throughput Screening (HTS) of different stoichiometric ratios, as a low material consumption screening strategy. This strategy is presented herein as a Quality by Design (QbD) crystal engineering approach, combined with experimental screening methods to produce cocrystals of a novel 5-Lipoxygenase (5-LO) inhibitor, PF-04191834 (PF4). Through this methodology, three new cocrystals were indicated for PF4, confirmed via DSC and XRPD, from less than 50 mg of original testing material. Part B of this study will demonstrate the scalability of this technique continuous extrusion.

Biocompatible Nano-Cocrystal Engineering for Targeted Herbicide Delivery: Enhancing Efficacy through Stimuli-Responsive Release and Reduced Environmental Losses

In addressing the critical challenges posed by the misuse and inefficiency of traditional pesticides, we introduce a Nano-Cocrystal material composed of the herbicide clopyralid and coformer phenazine. Developed through synergistic supramolecular self-assembly and mechanochemical nanotechnology, this Nano-Cocrystal significantly enhances pesticide performance. It exhibits a marked improvement in stability, with reductions in hygroscopicity and volatility by approximately 38%. Moreover, it intelligently modulates release according to environmental factors, such as temperature, pH, and soil inorganic salts, demonstrating decreased solubility by up to four times and improved wettability and adhesion on leaf surfaces. Importantly, the herbicidal activity surpasses that of pure clopyralid, increasing suppression rates of Medicago sativa L. and Oxalis corniculata L. by up to 27% at the highest dosage. This Nano-Cocrystal also shows enhanced crop safety and reduced genotoxicity compared to conventional formulations. Offering a blend of simplicity, cost-effectiveness, and robust stability, our findings contribute a sustainable solution to agricultural practices, favoring the safety of nontarget organisms.

Screening, Synthesis, and Characterization of a More Rapidly Dissolving Celecoxib Crystal Form

The prevalence of poor solubility in active pharmaceutical ingredients (APIs) such as celecoxib (CEL) is a major bottleneck in the pharmaceutical industry, leading to a low concentration gradient, poor passive diffusion, and in vivo failure. This study presents the synthesis and characterization of a new cocrystal of the API CEL. CEL is a nonsteroidal anti-inflammatory drug used for the treatment of osteoarthritis and rheumatoid arthritis. Computational screening was completed for CEL against a large library of generally recognized as safe (GRAS) coformers, based on molecular complementarity and hydrogen bond propensity (HBP). The generated list of 17 coformers with a likelihood for cocrystallization with CEL were experimentally screened using four techniques: liquid-assisted grinding (LAG), solvent evaporation (SE), gas antisolvent crystallization (GAS), and supercritical enhanced atomization (SEA). One new crystalline form was isolated, employing the liquid coformer N-ethylacetamide (NEA). This novel form, celecoxib-di-N-ethylacetamide (CEL·2NEA), was characterized by a variety of different techniques. The crystal structure was determined through single-crystal X-ray diffraction. Both NEA molecules are evolved from the crystal structure at a desolvation temperature of approximately 65 °C. The CEL·2NEA cocrystal exhibited a dissolution rate, with more than a twofold improvement in comparison to as-received CEL after only 15 min.

Multicomponent Amorphous Solid Forms of Telmisartan: Insights into Mechanochemical Activation and Physicochemical Attributes

The present work aims to explore the new solid forms of telmisartan (TEL) with alpha-ketoglutaric acid (KGA) and glutamic acid (GA) as potential coformers using mechanochemical approach and their role in augmentation in physicochemical parameters over pure crystalline TEL. Mechanochemical synthesis was performed using 1:1 stoichiometric ratio of TEL and the selected coformers in the presence of catalytic amount of ethanol for 1 h. The ground product was characterized by PXRD, DSC, and FTIR. The new solid forms were evaluated for apparent solubility, intrinsic dissolution, and physical stability. Preliminary characterization revealed the amorphization of the mechanochemical product as an alternate outcome of cocrystallization screening. Mechanistic understanding of the amorphous phase highlights the formation of amorphous-mediated cocrystallization that involves three steps, viz., molecular recognition, intermediate amorphous phase, and product nucleation. The solubility curves of both multicomponent amorphous solid forms (TEL-KGA and TEL-GA) showed the spring-parachute effect and revealed significant augmentation in apparent solubility (8-10-folds), and intrinsic dissolution release (6-9-folds) as compared to the pure drug. Besides, surface anisotropy and differential elemental distributions in intrinsic dissolution compacts of both solid forms were confirmed by FESEM and EDX mapping. Therefore, amorphous phases prepared from mechanochemical synthesis can serve as a potential solid form for the investigation of a cocrystal through amorphous-mediated cocrystallization. This has greater implications in solubility kinetics wherein the rapid precipitation of the amorphous phase can be prevented by the metastable cocrystal phase and contribute to the significant augmentation in the physicochemical parameters.

Cocrystals of a coumarin derivative: an efficient approach towards anti-leishmanial cocrystals against MIL-resistant Leishmania tropica

Leishmaniasis is a neglected parasitic tropical disease with numerous clinical manifestations. One of the causative agents of cutaneous leishmaniasis (CL) is Leishmania tropica (L. tropica) known for causing ulcerative lesions on the skin. The adverse effects of the recommended available drugs, such as amphotericin B and pentavalent antimonial, and the emergence of drug resistance in parasites, mean the search for new safe and effective anti-leishmanial agents is crucial. Miltefosine (MIL) was the first recommended oral medication, but its use is now limited because of the rapid emergence of resistance. Pharmaceutical cocrystallization is an effective method to improve the physicochemical and biological properties of active pharmaceutical ingredients (APIs). Herein, we describe the cocrystallization of coumarin-3-carboxylic acid (CU, 1a; 2-oxobenzopyrane-3-carboxylic acid, C10H6O4) with five coformers [2-amino-3-bromopyridine (1b), 2-amino-5-(trifluoromethyl)-pyridine (1c), 2-amino-6-methylpyridine (1d), p-aminobenzoic acid (1e) and amitrole (1f)] in a 1:1 stoichiometric ratio via the neat grinding method. The cocrystals 2-6 obtained were characterized via single-crystal X-ray diffraction, powder X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis, as well as Fourier transform infrared spectroscopy. Non-covalent interactions, such as van der Waals, hydrogen bonding, C-H...π and π...π interactions contribute significantly towards the packing of a crystal structure and alter the physicochemical and biological activity of CU. In this research, newly synthesized cocrystals were evaluated for their anti-leishmanial activity against the MIL-resistant L. tropica and cytotoxicity against the 3T3 (normal fibroblast) cell line. Among the non-cytotoxic cocrystals synthesized (2-6), CU:1b (2, IC50 = 61.83 ± 0.59 µM), CU:1c (3, 125.7 ± 1.15 µM) and CU:1d (4, 48.71 ± 0.75 µM) appeared to be potent anti-leishmanial agents and showed several-fold more anti-leishmanial potential than the tested standard drug (MIL, IC50 = 169.55 ± 0.078 µM). The results indicate that cocrystals 2-4 are promising anti-leishmanial agents which require further exploration.

Quabodepistat (OPC-167832), a Novel Antituberculosis Drug Candidate: Enhancing Oral Bioavailability via Cocrystallization and Mechanistic Analysis of Bioavailability in Two Cocrystals

Quabodepistat (code name OPC-167832) is a novel antituberculosis drug candidate. This study aimed to discover cocrystals that improve oral bioavailability and to elucidate the mechanistic differences underlying the bioavailability of different cocrystals. Screening yielded two cocrystals containing 2,5-dihydroxybenzoic acid (2,5DHBA) or 2-hydroxybenzoic acid (2HBA). In bioavailability studies in beagle dogs, both cocrystals exhibited better bioavailability than the free form; however, the extent of bioavailability of cocrystals with 2HBA (quabodepistat-2HBA) was 1.4-fold greater than that of cocrystals with 2,5DHBA (quabodepistat-2,5DHBA). Dissolution studies at pH 1.2 yielded similar profiles for both cocrystals, although the percent dissolution differed: quabodepistat-2HBA dissolved more slowly than quabodepistat-2,5DHBA. The poor solubility of quabodepistat-2HBA is likely the primary factor limiting dissolution at pH 1.2. To identify a dissolution method that maintains the bioavailability in beagle dogs, we performed pH-shift dissolution studies that mimic the dynamic pH change from the stomach to the small intestine. Quabodepistat-2HBA demonstrated supersaturation after the pH was increased to 6.8, while quabodepistat-2,5DHBA did not demonstrate supersaturation. This result was consistent with the results of bioavailability studies in beagle dogs. We conclude that a larger quantity of orally administered quabodepistat-2HBA remained in its cocrystal form while being transferred to the small intestine compared with quabodepistat-2,5DHBA.

Norfloxacin Cocrystals: Mechanochemical Synthesis and Scale-up Viability Through Solubility Studies

Cocrystals are recognized as one of the most efficient approaches to improve aqueous solubility of Biopharmaceutical Classification System, BCS, classes II and IV drugs. Cocrystal discovery and the establishment of experimental conditions suitable for scale-up purposes are some of the main challenges in cocrystal investigation. In this work, the investigation of mechanochemical synthesis of norfloxacin cocrystals with picolinic and isonicotinic acids is performed, leading to the discovery of two new cocrystals of this important BCS class IV antibiotic, which were characterized through thermal, spectral and diffractometric analysis. Norfloxacin apparent aqueous solubility using the cocrystals is also presented, with higher values being obtained for all the investigated systems when compared to the pure drug. Norfloxacin has 3 polymorphs and several solvents/hydrates, which represents a challenge for obtaining pure cocrystal forms from solvent crystallization. This challenge was successfully overcome in this work, as experimental conditions to obtain the pure cocrystals (the new ones and also norfloxacin-nicotinic acid and norfloxacin-saccharin) were established using Crystal16 equipment. This is a crucial step to envisage future scale-up procedures and therefore a valuable information for the pharmaceutical industry.

Pharmaceutical Cocrystal Discovery via 3D-SMINBR: A New Network Recommendation Tool Augmented by 3D Molecular Conformations

Cocrystals have significant potential in various fields such as chemistry, material, and medicine. For instance, pharmaceutical cocrystals have the ability to address issues associated with physicochemical and biopharmaceutical properties. However, it can be challenging to find proper coformers to form cocrystals with drugs of interest. Herein, a new in silico tool called 3D substructure-molecular-interaction network-based recommendation (3D-SMINBR) has been developed to address this problem. This tool first integrated 3D molecular conformations with a weighted network-based recommendation model to prioritize potential coformers for target drugs. In cross-validation, the performance of 3D-SMINBR surpassed the 2D substructure-based predictive model SMINBR in our previous study. Additionally, the generalization capability of 3D-SMINBR was confirmed by testing on unseen cocrystal data. The practicality of this tool was further demonstrated by case studies on cocrystal screening of armillarisin A (Arm) and isoimperatorin (iIM). The obtained Arm-piperazine and iIM-salicylamide cocrystals present improved solubility and dissolution rate compared to their parent drugs. Overall, 3D-SMINBR augmented by 3D molecular conformations would be a useful network-based tool for cocrystal discovery. A free web server for 3D-SMINBR can be freely accessed at http://lmmd.ecust.edu.cn/netcorecsys/.

Exploring the Supramolecular Interactions and Thermal Stability of Dapsone:Bipyridine Cocrystals by Combining Computational Chemistry with Experimentation

The application of computational screening methodologies based on H-bond propensity scores, molecular complementarity, molecular electrostatic potentials, and crystal structure prediction has guided the discovery of novel cocrystals of dapsone and bipyridine (DDS:BIPY). The experimental screen, which included mechanochemical and slurry experiments as well as the contact preparation, resulted in four cocrystals, including the previously known DDS:4,4'-BIPY (2:1, CC₄₄-B) cocrystal. To understand the factors governing the formation of the DDS:2,2'-BIPY polymorphs (1:1, CC₂₂-A and CC₂₂-B) and the two DDS:4,4'-BIPY cocrystal stoichiometries (1:1 and 2:1), different experimental conditions (such as the influence of solvent, grinding/stirring time, etc.) were tested and compared with the virtual screening results. The computationally generated (1:1) crystal energy landscapes had the experimental cocrystals as the lowest energy structures, although distinct cocrystal packings were observed for the similar coformers. H-bonding scores and molecular electrostatic potential maps correctly indicated cocrystallization of DDS and the BIPY isomers, with a higher likelihood for 4,4'-BIPY. The molecular conformation influenced the molecular complementarity results, predicting no cocrystallization for 2,2'-BIPY with DDS. The crystal structures of CC₂₂-A and CC₄₄-A were solved from powder X-ray diffraction data. All four cocrystals were fully characterized by a range of analytical techniques, including powder X-ray diffraction, infrared spectroscopy, hot-stage microscopy, thermogravimetric analysis, and differential scanning calorimetry. The two DDS:2,2'-BIPY polymorphs are enantiotropically related, with form B being the stable polymorph at room temperature (RT) and form A being the higher temperature form. Form B is metastable but kinetically stable at RT. The two DDS:4,4'-BIPY cocrystals are stable at room conditions; however, at higher temperatures, CC₄₄-A transforms to CC₄₄-B. The cocrystal formation enthalpy order, derived from the lattice energies, was calculated as follows: CC₄₄-B > CC₄₄-A > CC₂₂-A.

API co-crystals - Trends in CMC-related aspects of pharmaceutical development beyond solubility

Whereas pharmaceutical co-crystals are widely described as tool to improve solubility and dissolution behavior of poorly soluble drugs, so far less focus has been on their potential role to facilitate pharmaceutical manufacturability. This review summarizes recent developments in co-crystal research regarding new trends in co-crystal preparation routes and control of solid-state material attributes. Also, recent literature was reviewed to assess risks for co-crystals in formulation processes. A growing number of publications suggest that co-crystals show potential to specifically improve mechanical properties such as tabletability and compressibility, which can often be linked to intrinsic features of crystal structure properties. However, such trends must be treated with care, as molecular structures in reported co-crystal studies are not representative in some structural parameters governing also solid-state behavior (smaller molecular weight, more balanced hydrogen bond donor versus acceptor counts) compared to recent market approved small molecule drugs.

Co-crystal nanoarchitectonics as an emerging strategy in attenuating cancer: Fundamentals and applications

Cancer ranks as the second foremost cause of death in various corners of the globe. The clinical uses of assorted anticancer therapeutics have been limited owing to the poor physicochemical attributes, pharmacokinetic performance, and lethal toxicities. Various sorts of co-crystals or nano co-crystals or co-crystals-laden nanocarriers have presented great promise in targeting cancer via improved physicochemical attributes, pharmacokinetic performance, and reduced toxicities. These systems have also demonstrated the controlled cargo release and passive targeting via enhanced permeation and retention (EPR) effect. In addition, regional delivery of co-crystals via inhalation and transdermal route displayed remarkable potential in targeting lung and skin cancer effectively. However, more research is required on the use of co-crystals in cancer and their commercialization. The present review mainly emphasizes co-crystals as emerging avenues in the treatment of various cancers by modulating the physicochemical and pharmacokinetic attributes of approved anticancer therapeutics. The worth of co-crystals in cancer treatment, computational paths in the co-crystals screening, diverse experimental techniques of co-crystals fabrication, and sorts of co-crystals and their noteworthy applications in targeting cancer are also discussed. Besides, the game changer approaches like nano co-crystals and co-crystals-laden nanocarriers, and co-crystals in regional delivery in cancer are also explained with reported case studies. Furthermore, regulatory directives for pharmaceutical co-crystals and their scale-up, and challenges are also highlighted with concluding remarks and future initiatives. In essence, co-crystals and nano co-crystals emerge to be a promising strategy in overwhelming cancers through improving anticancer efficacy, safety, patient compliance, and reducing the cost.

Quantitative Monitoring of Cocrystal Polymorphisms in Model Tablets Using Transmission Low-Frequency Raman Spectroscopy

Cocrystallization is a technique for improving the physical properties of active pharmaceutical ingredients. However, cocrystals can transform into more stable polymorphs as well as dissociate to original materials. Therefore, an analytical technique is required to determine the polymorphic transformation quickly and accurately in tablets. The purpose of this study is to develop a method to monitor cocrystal polymorphs in model tablets using transmission low-frequency Raman spectroscopy. The tablets, consisting of only metastable polymorphs of caffeine-glutaric acid cocrystals, were stored under various relative humidity levels. The composition of the cocrystal polymorphs were calculated from a calibration curve relating the actual composition to the predicted values calculated by partial least squares regression processing of low-frequency Raman spectra. The metastable form gradually converted to a stable form, and polymorphic phase transformation occurred with increasing relative humidity. Ninety-six percent of the metastable form converted into a stable form stored at 25 °C after 3 h at 95% RH. In conclusion, transmission low-frequency Raman spectroscopy can be used to quantitatively monitor cocrystal polymorphs. This technique is one of the candidate techniques to quantifiably evaluate the physico-chemical stability of cocrystal polymorphs in tablets.

Pharmaceutical Co-crystal of Antiviral Agent Efavirenz with Nicotinamide for the Enhancement of Solubility, Physicochemical Stability, and Oral Bioavailability

The present research work attempted to improve the oral bioavailability of the antiviral drug Efavirenz (EFV) using a pharmaceutical cocrystallization technique. EFV comes under BCS-II and has extremely low water solubility, and results in low oral bioavailability. EFV and nicotinamide (NICO) were selected in a (1:1) stoichiometric ratio and efavirenz nicotinamide cocrystal (ENCOC) was prepared through the liquid-assisted grinding method (LAG). The confirmation of the formation of a new solid phase was done through spectroscopic techniques like Fourier transmission infrared (FTIR), Raman, and ¹³C solid-state nuclear magnetic resonance (¹³C ssNMR). Thermal techniques like differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and hot stage microscopy (HSM) illustrated the thermal behavior and melting patterns of ENCOC, EFV, and NICO. The X-ray powder diffraction (XRPD) confirms the formation of a new crystalline phase in ENCOC. The Morphology was determined through scanning electron microscopy (FESEM). The results of saturated solubility studies and in vitro drug release studies exhibited 8.9-fold enhancement in solubility and 2.56-fold enhancement in percentage cumulative drug release. The percentage drug content of ENCOC was found higher than 97% and cocrystal exhibits excellent accelerated stability. The oral bioavailability of EFV (C_max, 799.08 ng/mL) exhibits significant enhancement after cocrystallization (C_max, 5597.09 ng/mL) than EFV and Efcure®-200 tablet (2896.21 ng/mL). The current work investigates the scalable and cost-effective method for enhancement of physicochemical stability, solubility, and oral bioavailability of an antiviral agent EFV.

Nano- and Crystal Engineering Approaches in the Development of Therapeutic Agents for Neoplastic Diseases

Cancer is a leading cause of death worldwide. It is a global quandary that requires the administration of many different active pharmaceutical ingredients (APIs) with different characteristics. As is the case with many APIs, cancer treatments exhibit poor aqueous solubility which can lead to low drug absorption, increased doses, and subsequently poor bioavailability and the occurrence of more adverse events. Several strategies have been envisaged to overcome this drawback, specifically for the treatment of neoplastic diseases. These include crystal engineering, in which new crystal structures are formed to improve drug physicochemical properties, and/or nanoengineering in which the reduction in particle size of the pristine crystal results in much improved physicochemical properties. Co-crystals, which are supramolecular complexes that comprise of an API and a co-crystal former (CCF) held together by non-covalent interactions in crystal lattice, have been developed to improve the performance of some anti-cancer drugs. Similarly, nanosizing through the formation of nanocrystals and, in some cases, the use of both crystal and nanoengineering to obtain nano co-crystals (NCC) have been used to increase the solubility as well as overall performance of many anticancer drugs. The formulation process of both micron and sub-micron crystalline formulations for the treatment of cancers makes use of relatively simple techniques and minimal amounts of excipients aside from stabilizers and co-formers. The flexibility of these crystalline formulations with regards to routes of administration and ability to target neoplastic tissue makes them ideal strategies for effectiveness of cancer treatments. In this review, we describe the use of crystalline formulations for the treatment of various neoplastic diseases. In addition, this review attempts to highlight the gaps in the current translation of these potential treatments into authorized medicines for use in clinical practice.

A molecularly enhanced proof of concept for targeting cocrystals at molecular scale in continuous pharmaceuticals cocrystallization

It is impossible to optimize a process for a target drug product with the desired profile without a proper understanding of the interplay among the material attributes, the process parameters, and the attributes of the drug product. There is a particular need to bridge the micro- and mesoscale events that occur during this process. Here, we propose а molecular engineering methodology for the continuous cocrystallization process, based on Raman spectra measured experimentally with a probe and from quantum mechanical calculations. Using molecular dynamics simulations, the theoretical Raman spectra were calculated from first principles for local mixture structures under an external shear force at various temperatures. A proof of concept is developed to build the process design space from the computed data. We show that the determined process design space provides valuable insight for optimizing the cocrystallization process at the nanoscale, where experimental measurements are difficult and/or inapplicable. The results suggest that our method may be used to target cocrystallization processes at the molecular scale for improved pharmaceutical synthesis.

Three-Dimensional Supramolecular Architectures with MnII Ions Assembled from Hydrogen Bonding Interactions: Crystal Structures and Antiferromagnetic Properties

Two novel cocrystal Mn^II compounds were successfully synthesized. The composition of two kinds crystals correspond to [Mn(hfac)₂L^a ₂·Mn(hfac)₂L^a(H₂O)·Mn(hfac)₂(H₂O)₂] (1) and [Mn(hfac)₂L^b ₂·Mn(hfac)₂(H₂O)₂·0.5(C₆H₁₄)] (2) [L^a = 1,3-bis(1'-oxyl-3'-oxido-4',4',5',5'-tetramethyl-4,5-dihydro-1H-imidazol-2-y1)benzene; L^b = 1-(1'-oxyl-4',4',5',5'-tetramethylimidazolin-2-yl)-3-(1'-oxyl-3'-oxo-4',4',5',5'-tetramethylimidazolin-2-yl)benzene; hfac = hexafluoroacetylacetonato). Surprisingly, the compounds were not polymeric or clusters but, more interestingly, different ratio biradical-metal coordination compound cocrystals. The extensive intramolecular H-bonds are the cause of formation of the cocrystal structures by assembly in the two manganese(II) derivatives; and another factor is the halogen bonds between CF₃ of hfac groups. Furthermore, three-dimensional supramolecular architectures were formed. The magnetic susceptibility of both compounds showed strong antiferromagnetic interactions involving the coordinated radical unit and the metal and lesser contribution from ferromagnetic interactions between the radical units. For compound 1, a good fit was obtained for g _Mn = 2.08, g _rad = 2.00 (fixed), J ₁ = -294.3 cm^-1, J ₂ = 6.2 cm^-1 and J ₃ = 10.8 cm^-1. A reasonable fit for compound 2 was obtained for g _Mn = 2.04, g _rad = 2.00 (fixed), J ₁' = -273.4 cm^-1 and J ₂' = 8.6 cm^-1.

Nanostructured lipid carriers loaded with an association of minoxidil and latanoprost for targeted topical therapy of alopecia

Alopecia is a condition associated with different etiologies, ranging from hormonal changes to chemotherapy, that affects over 80 million people in the USA. Nevertheless, there are currently few FDA-approved drugs for topical treatment, and existing formulations still present skin irritation issues, compromising treatment adherence. This work aimed to develop a safe formulation based on nanostructured lipid carriers (NLC) that entrap an association of minoxidil and latanoprost and target drug delivery to the hair follicles. To do so, thermal techniques combined with FTIR were used to assess the chemical compatibility of the proposed drug association. Then, NLC with 393.5 ± 36.0 nm (PdI<0.4) and +22.5 ± 0.2 mV zeta potential were produced and shown to entrap 86.9% of minoxidil and 99.9% of latanoprost efficiently. In vitro, the free drug combination was indicated to exert positive effects over human primary epidermal keratinocytes, supporting cell proliferation, migration and inducing the mRNA expression of MKI67 proliferation marker and VEGF - a possible effector for minoxidil-mediated hair growth. Interestingly, such a favorable drug combination profile was optimized when delivered using our NLC. Furthermore, according to the HET-CAM and reconstructed human epidermis assays, the nanoformulation was well tolerated. Finally, drug penetration was evaluated in vitro using porcine skin. Such experiments indicated that the NLC could be deposited preferentially into the hair follicles, causing a considerable increase in the penetration of the two drugs in such structures, compared to the control (composed of the free compounds) and generating a target-effect of approximately 50% for both drugs. In summary, present results suggest that hair follicle-targeted delivery of the minoxidil and latanoprost combination is a promising alternative to treat alopecia.

Better and greener: sustainable pharmaceutical manufacturing technologies for highly bioavailable solid dosage forms

In the last decades, Green Chemistry has been gaining widespread attention within the pharmaceutical field. It is thus very important to bring more sustainable approaches into the design and manufacture of effective oral drug delivery systems. This review focuses on spray congealing and mechanochemical activation, two technologies endorsing different principles of green chemistry, and at the same time, addressing some of the challenges related to the transformation of poorly water-soluble drugs in highly bioavailable solid dosage forms. We therefore present an overview of the basic principles, equipment, and application of these particle-engineering technologies, with specific attention to case studies carried out by the groups working in Italian Universities.

Thermal Methods Usage Features for Multicomponent Crystals Screening

Effectiveness of thermal methods, liquid-assisted grinding (LAG), and crystallization by slow evaporation technique for screening of multicomponent crystals of quinolones (nalidixic acid (NLD), oxolinic acid (OXL), norfloxacin (NFX), levofloxacin (LFX),...

Recent Advances in Pharmaceutical Cocrystals: From Bench to Market

The pharmacokinetics profile of active pharmaceutical ingredients (APIs) in the solid pharmaceutical dosage forms is largely dependent on the solid-state characteristics of the chemicals to understand the physicochemical properties by particle size, size distribution, surface area, solubility, stability, porosity, thermal properties, etc. The formation of salts, solvates, and polymorphs are the conventional strategies for altering the solid characteristics of pharmaceutical compounds, but they have their own limitations. Cocrystallization approach was established as an alternative method for tuning the solubility, permeability, and processability of APIs by introducing another compatible molecule/s into the crystal structure without affecting its therapeutic efficacy to successfully develop the formulation with the desired pharmacokinetic profile. In the present review, we have grossly focused on cocrystallization, particularly at different stages of development, from design to production. Furthermore, we have also discussed regulatory guidelines for pharmaceutical industries and challenges associated with the design, development and production of pharmaceutical cocrystals with commercially available cocrystal-based products.

Four Novel Pharmaceutical Cocrystals of Oxyresveratrol, Including a 2 : 3 Cocrystal with Betaine

Cocrystal engineering can alter the physicochemical properties of a drug and generate a superior drug candidate for formulation design. Oxyresveratrol (ORV) exhibits a poor solubility in aqueous environments, thereby resulting in a poor bioavailability. Extensive cocrystal screening of ORV with 67 cocrystal formers (coformers) bearing various functional groups was therefore conducted using grinding, liquid-assisted grinding, solvent evaporation, and slurry methods. Six cocrystals (ORV with betaine (BTN), L-proline (PRL), isonicotinamide, nicotinamide, urea, and ethyl maltol) were found, including four novel cocrystals. Powder X-ray diffraction, low frequency Raman spectroscopy, and thermal analysis revealed unique crystal forms in all obtained samples. Conventional Raman and infrared data differentiated the cocrystals by the presence or absence of a hydrogen bond interacting with the aromatic ring of ORV. The crystal structures were then elucidated by single-crystal X-ray diffraction. Two new cocrystals consisting of ORV : BTN (2 : 3) and ORV : PRL : H₂O (1 : 2 : 1) were identified, and their crystal structures were solved. We report novel cocrystalline solids of ORV with improved aqueous solubilities and the unique cage-like crystal structures.

SMINBR: An Integrated Network and Chemoinformatics Tool Specialized for Prediction of Two-Component Crystal Formation

Two-component crystals such as pharmaceutical cocrystals and salts have been proven as an effective strategy to improve physicochemical and biopharmaceutical properties of drugs. It is not easy to select proper molecular combinations to form two-component crystals. The network-based models have been successfully utilized to guide cocrystal design. Yet, the traditional social network-derived methods based on molecular-interaction topology information cannot directly predict interaction partners for new chemical entities (NCEs) that have not been observed to form two-component crystals. Herein, we proposed an effective tool, namely substructure-molecular-interaction network-based recommendation (SMINBR), to prioritize potential interaction partners for NCEs. This in silico tool incorporates network and chemoinformatics methods to bridge the gap between NCEs and known molecular-interaction network. The high performance of 10-fold cross validation and external validation shows the high accuracy and good generalization capability of the model. As a case study, top 10 recommended coformers for apatinib were all experimentally confirmed and a new apatinib cocrystal with paradioxybenzene was obtained. The predictive capability of the model attributes to its accordance with complementary patterns driving the formation of intermolecular interactions. SMINBR could automatically recommend new interaction partners for a target molecule, and would be an effective tool to guide cocrystal design. A free web server for SMINBR is available at http://lmmd.ecust.edu.cn/sminbr/.

First and Second Dissociation Enthalpies in Bi-Component Crystals Consisting of Maleic Acid and L-Phenylalanine

The energetics of the stepwise dissociation of a A:B₂ bi-component crystal, according to A:B₂(cr) → A:B(cr) + B(cr) and A:B(cr) → A(cr) + B(cr), was investigated using MA:Phe₂ and MA:Phe (MA = maleic acid; Phe = L-phenylalanine) as model systems. The enthalpy changes associated with these sequential processes and with the overall dissociation reaction A:B₂(cr) → A(cr) + 2B(cr) were determined by solution calorimetry. It was found that they are all positive, indicating that there is a lattice enthalpy gain when MA:Phe₂ is formed, either from the individual precursors or by adding Phe to MA:Phe. Single-crystal X-ray diffraction (SCXRD) analysis showed that MA:Phe₂ is best described as a protic salt containing a maleate anion (MA⁻) and two non-equivalent L-phenylalanine units, both linked to MA⁻ by NH···O hydrogen bonds (H-bond): one of these units is protonated (HPhe⁺) and the other zwitterionic (Phe^±). Only MA⁻ and HPhe⁺ molecules are present in the MA:Phe lattice. In this case, however, NH···O and OH···O H-bonds are formed between each MA⁻ unit and two HPhe⁺ molecules. Despite these structural differences, the enthalpy cost for the removal of the zwitterionic Phe^± unit from the MA:Phe₂ lattice to yield MA:Phe is only 0.9 ± 0.4 kJ mol⁻¹ higher than that for the dissociation of MA:Phe, which requires a proton transfer from HPhe⁺ to MA⁻ and the rearrangement of L-phenylalanine to the zwitterionic, Phe^±, form. Finally, a comparison of the dissociation energetics and structures of MA:Phe and of the previously reported glycine maleate (MA:Gly) analogue indicated that parameters, such as the packing coefficient, density, hydrogen bonds formed, or fusion temperature, are not necessarily good descriptors of dissociation enthalpy or lattice enthalpy trends when bi-component crystals with different molecular composition are being compared, even if the stoichiometry is the same.

Zaltoprofen/4,4'-Bipyridine: A Case Study to Demonstrate the Potential of Differential Scanning Calorimetry (DSC) in the Pharmaceutical Field

The Zaltoprofen/4,4'-Bipyridine system gives rise to two co-crystals of different compositions both endowed - in water and in buffer solution at pH 4.5 - with considerably higher solubility and dissolution rate than the pure drug. The qualitative and quantitative analysis of the DSC measurements, carried out on samples made up of mixtures prepared according to different methodologies, allows us to elaborate and propose an accurate thermodynamic model that fully takes into account the qualitative aspects of the complex experimental framework and which provides quantitative predictions (reaction enthalpies and compositions of the co-crystals) in excellent agreement with the experimental results. Co-crystal formation and cocrystal compositions were confirmed by X-ray diffraction measurements as well as by FT-IR and NMR spectroscopy measurements. The quantitative processing of DSC measurements rationalizes and deepens the scientific aspects underlying the so-called Tammann's triangle and constitutes a model of general validity. The work shows that DSC has enormous potential, which however can be fully exploited only by paying adequate attention to the experimental aspects and the quantitative processing of the measurements.

Obtaining Cocrystals by Reaction Crystallization Method: Pharmaceutical Applications

Cocrystals have gained attention in the pharmaceutical industry due to their ability to improve solubility, stability, in vitro dissolution rate, and bioavailability of poorly soluble drugs. Conceptually, cocrystals are multicomponent solids that contain two or more neutral molecules in stoichiometric amounts within the same crystal lattice. There are several techniques for obtaining cocrystals described in the literature; however, the focus of this article is the Reaction Crystallization Method (RCM). This method is based on the generation of a supersaturated solution with respect to the cocrystal, while this same solution is saturated or unsaturated with respect to the components of the cocrystal individually. The advantages of the RCM compared with other cocrystallization techniques include the ability to form cocrystals without crystallization of individual components, applicability to the development of in situ techniques for the screening of high quality cocrystals, possibility of large-scale production, and lower cost in both time and materials. An increasing number of scientific studies have demonstrated the use of RCM to synthesize cocrystals, mainly for drugs belonging to class II of the Biopharmaceutics Classification System. The promising results obtained by RCM have demonstrated the applicability of the method for obtaining pharmaceutical cocrystals that improve the biopharmaceutical characteristics of drugs.

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.

Continuous Manufacture and Scale-Up of Theophylline-Nicotinamide Cocrystals

The aim of the study was the manufacturing and scale-up of theophylline-nicotinamide (THL-NIC) pharmaceutical cocrystals processed by hot-melt extrusion (HME). The barrel temperature profile, feed rate and screw speed were found to be the critical processing parameters with a residence time of approximately 47 s for the scaled-up batches. Physicochemical characterization using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction of bulk and extruded materials revealed the formation of high purity cocrystals (98.6%). The quality of THL-NIC remained unchanged under accelerated stability conditions.

Solution Cocrystallization: A Scalable Approach for Cocrystal Production

With an increasing interest in cocrystals due to various advantages, demand for large-scale cocrystallization techniques is rising. Solution cocrystallization is a solvent-based approach that utilizes several single-component crystallization concepts as well as equipment for generating cocrystals. Solution-based techniques can produce cocrystals with reasonable control on purity, size distribution, morphology, and polymorphic form. Many of them also offer a scalable solution for the industrial production of cocrystals. However, the complexity of the thermodynamic landscape and the kinetics of cocrystallization offers fresh challenges which are not encountered in single component crystallization. This review focuses on the recent developments in different solution cocrystallization techniques for the production of pharmaceutically relevant cocrystals. The review consists of two sections. The first section describes the various solution cocrystallization methods, highlighting their benefits and limitations. The second section emphasizes the challenges in developing these techniques to an industrial scale and identifies the major thrust areas where further research is required.

Cocrystal engineering of pharmaceutical solids: therapeutic potential and challenges

This highlight presents an overview of pharmaceutical cocrystal production and its potential in reviving problematic properties of drugs in different dosage forms. The challenges and future outlook of its translational development are discussed.

Ternary Phase Diagram Development and Production of Niclosamide-Urea Co-Crystal by Spray Drying

In this work, a ternary phase diagram was developed for a Niclosamide-urea co-crystal (NCS-UR) in isopropanol (IPA) using a combination of slurry and solvent addition methods. The ternary phase diagram showed that solubility of Niclosamide and urea differed by an order of magnitude in IPA, leading to an incongruently saturating system. Spray drying was explored as a method to generate NCS-UR. Co-crystals with small, uniform particle size were successfully prepared by spray drying from equimolar solutions with yield up to 73%. Co-crystals were phase pure by X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) from all conditions explored. Somewhat similar particles were obtained at inlet temperature of 70 °C (mean size of 2.0 μm) compared to 85 °C (2.8-3.4 μm). Based on the TPD, isolating phase pure co-crystal through solution crystallization in IPA would require excess urea. However, spray drying did not require excess co-former. The in-vitro solubility of NCS-UR was compared to anhydrous NCS in biorelevant media. NCS-UR did not give improvement in solubility at 1 h or 24 h. Overall, this work showed that spray drying is a feasible process for preparing phase pure co-crystals for an incongruently saturating system and simultaneously generating micron size particles.

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.

Innovations in Thermal Processing: Hot-Melt Extrusion and KinetiSol® Dispersing

Thermal processing has gained much interest in the pharmaceutical industry, particularly for the enhancement of solubility, bioavailability, and dissolution of active pharmaceutical ingredients (APIs) with poor aqueous solubility. Formulation scientists have developed various techniques which may include physical and chemical modifications to achieve solubility enhancement. One of the most commonly used methods for solubility enhancement is through the use of amorphous solid dispersions (ASDs). Examples of commercialized ASDs include Kaletra®, Kalydeco®, and Onmel®. Various technologies produce ASDs; some of the approaches, such as spray-drying, solvent evaporation, and lyophilization, involve the use of solvents, whereas thermal approaches often do not require solvents. Processes that do not require solvents are usually preferred, as some solvents may induce toxicity due to residual solvents and are often considered to be damaging to the environment. The purpose of this review is to provide an update on recent innovations reported for using hot-melt extrusion and KinetiSol® Dispersing technologies to formulate poorly water-soluble APIs in amorphous solid dispersions. We will address development challenges for poorly water-soluble APIs and how these two processes meet these challenges.

Cocrystallization: Cutting Edge Tool for Physicochemical Modulation of Active Pharmaceutical Ingredients

Cocrystallization is a widely accepted and clinically relevant technique that has prospered very well over the past decades to potentially modify the physicochemical properties of existing active pharmaceutic ingredients (APIs) without compromising their therapeutic benefits. Over time, it has become an integral part of the pre-formulation stage of drug development because of its ability to yield cocrystals with improved properties in a way that other traditional methods cannot easily achieve. Cocrystals are solid crystalline materials composed of two or more than two molecules which are non-covalently bonded in the same crystal lattice. Due to the continuous efforts of pharmaceutical scientists and crystal engineers, today cocrystals have emerged as a cutting edge tool to modulate poor physicochemical properties of APIs such as solubility, permeability, bioavailability, improving poor mechanical properties and taste masking. The success of cocrystals can be traced back by looking at the number of products that are getting regulatory approval. At present, many cocrystals have obtained regulatory approval and they successfully made into the market place followed by a fair number of cocrystals that are currently in the clinical phases. Considering all these facts about cocrystals, the formulation scientists have been inspired to undertake more relevant research to extract out maximum benefits. Here in this review cocrystallization technique will be discussed in detail with respect to its background, different synthesis approaches, synthesis mechanism, application and improvements in drug delivery systems and its regulatory perspective.

Hot stage microscopy and its applications in pharmaceutical characterization

Hot stage microscopy (HSM) is a thermal analysis technique that combines the best properties of thermal analysis and microscopy. HSM is rapidly gaining interest in pharmaceuticals as well as in other fields as a regular characterization technique. In pharmaceuticals HSM is used to support differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA) observations and to detect small changes in the sample that may be missed by DSC and TGA during a thermal experiment. Study of various physical and chemical properties such sample morphology, crystalline nature, polymorphism, desolvation, miscibility, melting, solid state transitions and incompatibility between various pharmaceutical compounds can be carried out using HSM. HSM is also widely used to screen cocrystals, excipients and polymers for solid dispersions. With the advancements in research methodologies, it is now possible to use HSM in conjunction with other characterization techniques such as Fourier transform infrared spectroscopy (FTIR), DSC, Raman spectroscopy, scanning electron microscopy (SEM) which may have additional benefits over traditional characterization techniques for rapid and comprehensive solid state characterization.

Pharmaceutical Cocrystal Development of TAK-020 with Enhanced Oral Absorption

The objective of this study was to improve the solubility of poorly water-soluble drugs by pharmaceutical cocrystal engineering techniques and select the best pharmaceutical forms with high solubility and solubilized formulations for progress from the early discovery stage toward the clinical stage. Several pharmaceutical cocrystals of TAK-020, a Bruton tyrosine kinase inhibitor, were newly discovered in the screening based on the solid grinding method and the slurry method, considering thermodynamic factors that dominate cocrystal formation. TAK-020/gentisic acid cocrystal (TAK-020/GA CC) was selected based on a physicochemical property of enhanced dissolution rate. TAK-020/GA CC was proven to be a reliable cocrystal formation with a definitive stoichiometric ratio by a variety of analytical techniques—pKa calculation, solid-state nuclear magnetic resonance, and single X-ray structure analysis from the view of regulation. Furthermore, its absorption was remarkable and beyond those achieved in currently existing solubilized formulation techniques, such as nanocrystal, amorphous solid dispersion, and lipid-based formulation, in dog pharmacokinetic studies. TAK-020/GA CC was the best drug form, which might lead to good pharmacological effects with regard to enhanced absorption and development by physicochemical characterization. Through the trials of solid-state optimization from early drug discovery to pharmaceutical drug development, the cocrystals can be an effective option for achieving solubilization applicable in the pharmaceutical industry.

Considerations on high-throughput cocrystals screening by ultrasound assisted cocrystallization and vibrational spectroscopy

For industrial production of cocrystals, screening phase is essential, helping to become the process faster, more effective and efficient, reducing the quantity of reactants used and associated costs. High-throughput screening (HTS) methods can analyze a wide range of compounds simultaneously. As an answer to industrial necessity of more efficient screening methods, different methods must be developed and optimized. Vibrational spectroscopic techniques are fast, non-destructive and non-invasive, do not need pre-treatment of the samples and allow obtaining qualitative and quantitative information. They are useful in cocrystal analysis, once they detect weak interaction as hydrogen bonding, the basis of cocrystal formation. Therefore, its application in the analysis of cocrystal screening methods, together with multivariate analysis, should be studied in detail. For this end, a HTS procedure of hydrochlorothiazide (HTZ) cocrystals is performed using a 96-well plate and ultrasound-assisted cocrystallization. Six coformers were tested considering ratios of HTZ:coformer of 1:1 and 1:2. The cocrystallization products were analyzed by mid infrared spectroscopy and Raman microspectroscopy. Nicotinamide and p-aminobenzoic acid formed cocrystals with HTZ. The systems with arginine showed that the coformer suffered amorphization; however, no proof of the solid state of HTZ was obtained. The results were not conclusive for the system with citric acid. Additionally, in the nicotinamide and citric acid systems, the physical mixture of the plate also reacted without the present of solvent. Overall, the use of mid infrared spectroscopy and multivariate data analysis provided important information on cocrystal formation, purity, and correct ratio assessment.

Microwave assisted slurry conversion crystallization for manufacturing of new co-crystals of sulfamethazine and sulfamerazine

Formation of co-crystals is faster using microwaves than simple conductive/convective heating to the same temperature.

A New Ferulic Acid-Nicotinamide Cocrystal With Improved Solubility and Dissolution Performance

Among the various strategies for increasing aqueous solubility of pharmaceutical substances, cocrystals have been emerging as a promising alternative. The ferulic acid (FEA) is a molecule with limited aqueous solubility, but with an interesting pharmacological activity, highlighting its antitumor potential. This study presents the characterization and physicochemical properties of a new cocrystal based on FEA and nicotinamide (NIC). The FEA-NIC cocrystal was obtained by solvent evaporation technique and physicochemically characterized by differential scanning calorimetry, powder X-ray diffraction, Fourier transform infrared spectroscopy, solid-state nuclear magnetic resonance and scanning electron microscopy. The content determination and dissolution profile in different media were analyzed by high-performance liquid chromatography. The results obtained with the characterization techniques indicated the obtainment of an anhydrous cocrystal of FEA and NIC at a 1:1 molar ratio. The method was reproducible and obtained a high yield, of approximately 99%. In addition, a 70% increase in the FEA solubility in the cocrystal and a better dissolution performance than the physical mixture in pH 6.8 were achieved.