Formation of itraconazole/L-malic acid cocrystals by gas antisolvent cocrystallization

Explaining dissolution properties of rivaroxaban cocrystals

The aim of this study was to improve rivaroxaban water-solubility by cocrystal preparation and to understand this process. The screening with water-soluble coformers was performed via both mechanochemical and solution-mediated techniques. Two cocrystals of rivaroxaban with malonic acid and oxalic acid were prepared, and the structure of the cocrystal with oxalic acid was solved. Both cocrystals exhibit improved dissolution properties. The mechanism of the supersaturation maintenance was studied by in-situ Raman spectroscopy. The transformation into rivaroxaban dihydrate was identified as the critical step in the improved dissolution properties of both cocrystals. Moreover, the transformation kinetics and solubilization effects of the coformers were identified as responsible for the differences in the dissolution behavior of the cocrystals. In-vivo experiments proved that the use of cocrystal instead of form I of free API helped to increase the bioavailability ofrivaroxaban.

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.

Applications of Supercritical Anti-Solvent Process in Preparation of Solid Multicomponent Systems

Solid multicomponent systems (SMS) are gaining an increasingly important role in the pharmaceutical industry, to improve the physicochemical properties of active pharmaceutical ingredients (APIs). In recent years, various processes have been employed for SMS manufacturing. Control of the particle solid-state properties, such as size, morphology, and crystal form is required to optimize the SMS formulation. By utilizing the unique and tunable properties of supercritical fluids, supercritical anti-solvent (SAS) process holds great promise for the manipulation of the solid-state properties of APIs. The SAS techniques have been developed from batch to continuous mode. Their applications in SMS preparation are summarized in this review. Many pharmaceutical co-crystals and solid dispersions have been successfully produced via the SAS process, where the solid-state properties of APIs can be well designed by controlling the operating parameters. The underlying mechanisms on the manipulation of solid-state properties are discussed, with the help of on-line monitoring and computational techniques. With continuous researching, SAS process will give a large contribution to the scalable and continuous manufacturing of desired SMS in the near future.

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.

Improved Solubility and Dissolution Rates in Novel Multicomponent Crystals of Piperine with Succinic Acid

The objectives of this study were to prepare and characterize a novel piperine–succinic acid multicomponent crystal phase and to evaluate the improvement in the solubility and dissolution rate of piperine when prepared in the multicomponent crystal formation. The solid-state characterization of the novel multicomponent crystal was performed by powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform-infrared (FT-IR) spectroscopy. Solubility and dissolution rate profiles were evaluated in distilled water. The physical stability was evaluated under high relative humidity (75% and 100% RH). The determination of the single crystal X-ray diffraction structure revealed that this novel multicomponent crystal was a cocrystalline phase of piperine–succinic acid (2:1 molar ratio). The differential scanning calorimetry thermogram of the cocrystal showed a single and sharp endothermic peak at 110.49 °C. The cocrystal resulted in greater solubility and a faster dissolution rate of piperine than intact piperine. This improvement was a result of the formation of a channel structure in the cocrystal. In addition, the cocrystal was stable under a humid condition.

Synthesis of 5-hydroxy-2-methyl-naphthalene-1,4-dione cocrystals with pyridine-3-carboxamide using electrospray technology: physicochemical characterization and in vitro non-everted rat intestinal absorption study

Plumbagin with nicotinamide cocrystals synthesised by electrospray technology demonstrated two-, three- and nine-fold enhancements in solubility, dissolution and permeability coefficient.

Synthesis of fisetin co-crystals with caffeine and nicotinamide using the cooling crystallization technique: biopharmaceutical studies

A fisetin-caffeine co-crystal prepared by using cooling crystallization technology showed a two- and three-fold improvement in the solubility and oral bioavailability of fisetin.

Engineering Cocrystals of PoorlyWater-Soluble Drugs to Enhance Dissolution in Aqueous Medium

Biopharmaceutics Classification System (BCS) Class II and IV drugs suffer from poor aqueous solubility and hence low bioavailability. Most of these drugs are hydrophobic and cannot be developed into a pharmaceutical formulation due to their poor aqueous solubility. One of the ways to enhance the aqueous solubility of poorlywater-soluble drugs is to use the principles of crystal engineering to formulate cocrystals of these molecules with water-soluble molecules (which are generally called coformers). Many researchers have shown that the cocrystals significantly enhance the aqueous solubility of poorly water-soluble drugs. In this review, we present a consolidated account of reports available in the literature related to the cocrystallization of poorly water-soluble drugs. The current practice to formulate new drug cocrystals with enhanced solubility involves a lot of empiricism. Therefore, in this work, attempts have been made to understand a general framework involved in successful (and unsuccessful) cocrystallization events which can yield different solid forms such as cocrystals, cocrystal polymorphs, cocrystal hydrates/solvates, salts, coamorphous solids, eutectics and solid solutions. The rationale behind screening suitable coformers for cocrystallization has been explained based on the rules of five i.e., hydrogen bonding, halogen bonding (and in general non-covalent bonding), length of carbon chain, molecular recognition points and coformer aqueous solubility. Different techniques to screen coformers for effective cocrystallization and methods to synthesize cocrystals have been discussed. Recent advances in technologies for continuous and solvent-free production of cocrystals have also been discussed. Furthermore, mechanisms involved in solubilization of these solid forms and the parameters influencing dissolution and stability of specific solid forms have been discussed. Overall, this review provides a consolidated account of the rationale for design of cocrystals, past efforts, recent developments and future perspectives for cocrystallization research which will be extremely useful for researchers working in pharmaceutical formulation development.

Supercritical carbon dioxide-based technologies for the production of drug nanoparticles/nanocrystals - A comprehensive review

Low drug bioavailability, which is mostly a result of poor aqueous drug solubilities and of inadequate drug dissolution rates, is one of the most significant challenges that pharmaceutical companies are currently facing, since this may limit the therapeutic efficacy of marketed drugs, or even result in the discard of potential highly effective drug candidates during developmental stages. Two of the main approaches that have been implemented in recent years to overcome poor drug solubility/dissolution issues have frequently involved drug particle size reduction (i.e., micronization/nanonization) and/or the modification of some of the physicochemical and structural properties of poorly water soluble drugs. A large number of particle engineering methodologies have been developed, tested, and applied in the synthesis and control of particle size/particle-size distributions, crystallinities, and polymorphic purities of drug micro- and nano-particles/crystals. In recent years pharmaceutical processing using supercritical fluids (SCF), in general, and supercritical carbon dioxide (scCO₂), in particular, have attracted a great attention from the pharmaceutical industry. This is mostly due to the several well-known advantageous technical features of these processes, as well as to other increasingly important subjects for the pharmaceutical industry, namely their "green", sustainable, safe and "environmentally-friendly" intrinsic characteristics. In this work, it is presented a comprehensive state-of-the-art review on scCO₂-based processes focused on the formation and on the control of the physicochemical, structural and morphological properties of amorphous/crystalline pure drug nanoparticles. It is presented and discussed the most relevant scCO₂, scCO₂-based fluids and drug physicochemical properties that are pertinent for the development of successful pharmaceutical products, namely those that are critical in the selection of an adequate scCO₂-based method to produce pure drug nanoparticles/nanocrystals. scCO₂-based nanoparticle formation methodologies are classified in three main families, and in terms of the most important role played by scCO₂ in particle formation processes: as a solvent; as an antisolvent or a co-antisolvent; and as a "high mobility" additive (a solute, a co-solute, or a co-solvent). Specific particle formation methods belonging to each one of these families are presented, discussed and compared. Some selected amorphous/crystalline drug nanoparticles that were prepared by these methods are compiled and presented, namely those studied in the last 10-15 years. A special emphasis is given to the formation of drug cocrystals. It is also discussed the fundamental knowledge and the main mechanisms in which the scCO₂-based particle formation methods rely on, as well as the current status and urgent needs in terms of reliable experimental data and of robust modeling approaches. Other addressed and discussed topics include the currently available and the most adequate physicochemical, morphological and biological characterization methods required for pure drug nanoparticles/nanocrystals, some of the current nanometrology and regulatory issues associated to the use of these methods, as well as some scale-up, post-processing and pharmaceutical regulatory subjects related to the industrial implementation of these scCO₂-based processes. Finally, it is also discussed the current status of these techniques, as well as their future major perspectives and opportunities for industrial implementation in the upcoming years.

Advanced methodologies for cocrystal synthesis

Pharmaceutical cocrystals are multicomponent systems composed of two or more molecules and held together by H-bonding. Currently, cocrystals provide exciting opportunities in the pharmaceutical industry for the development and manufacturing of new medicines by improving poor physical properties of Active Pharmaceutical Ingredients (APIs) such as processability, solubility, stability and bioavailability. According to the recent reclassification, cocrystals are considered as drug polymorph rather a new API which has a significant impact on drug development, regulatory submissions and intellectual property protection. This review summarizes recent trends and advances in synthesis, manufacturing and scale - up of cocrystals. The operational principles of several cocrystals manufacturing technologies are discussed including their advantages and disadvantages in terms of crystal quality, purity stability, throughput and limitations in large scale production.

Preparation and characterization of adefovir dipivoxil-stearic acid cocrystal with enhanced physicochemical properties

The objectives of this study were to prepare cocrystal composed of adefovir dipivoxil (AD) and stearic acid (SA) and to investigate the enhanced properties of the cocrystal. The cocrystal was prepared by antisolvent precipitation and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRPD), and differential scanning calorimetry (DSC). The enhanced properties were evaluated by dissolution testing, permeability studies, and powder rheology analysis. The AD raw material has a cuboid-like crystal and the cocrystal has a needle shape. In the FT-IR study, there were bathochromic shifts caused by the hydrogen bonding. The melting point of the cocrystal was 52.9 °C, which was lower than that of AD. The XRPD pattern also had distinct differences, supporting the formation of a new crystalline form. The cocrystal showed changes in the lattice energy and the solvation strength, which caused an enhanced dissolution. The permeability was increased due to the SA, which acts as a P-gp inhibitor. The tabletability was enhanced due to the altered crystal habit. In conclusion, cocrystal containing AD and SA was successfully prepared, presenting advantages such as enhanced solubility, tabletability, and permeability. The use of the cocrystal is a desirable approach for the improved physicochemical properties.

Enhanced pulmonary absorption of poorly soluble itraconazole by micronized cocrystal dry powder formulations

Micronized cocrystal powders and amorphous spray-dried formulations were prepared and evaluated in vivo and in vitro as pulmonary absorption enhancement formulations of poorly soluble itraconazole (ITZ). ITZ cocrystals with succinic acid (SA) or l-tartaric acid (TA) with a particle size diameter of <2μm were successfully micronized using the jet-milling system. The cocrystal crystalline morphologies observed using scanning electron microscopy (SEM) suggested particle shapes that differed from those of the crystalline or spray-dried amorphous ITZ. The micronized ITZ cocrystal powders showed better intrinsic dissolution rate (IDR) and pulmonary absorption profile in rats than that of the amorphous spray-dried formulation and crystalline ITZ with comparable particle sizes. Specifically, in rat pharmacokinetic studies following pulmonary administration, micronized ITZ-SA and ITZ-TA cocrystals showed area under the curve from 0 to 8h (AUC_0-8h) values approximately 24- and 19-fold higher than those of the crystalline ITZ and 2.0- and 1.6-fold higher than the spray-dried ITZ amorphous values, respectively. The amorphous formulation appeared physically instable during the studies due to rapid crystallization of ITZ, which was its disadvantage compared to the crystalline formulations. Therefore, this study demonstrated that micronized cocrystals are promising formulations for enhancing the pulmonary absorption of poorly soluble compounds.

Preparation of pharmaceutical co-crystals through sustainable processes using supercritical carbon dioxide: a review

The preparation of pharmaceutical co-crystals using supercritical CO₂ (scCO₂) is reviewed.

Solubility and dissolution enhancement strategies: current understanding and recent trends

Identification of lead compounds with higher molecular weight and lower aqueous solubility has become increasingly prevalent with the advent of high throughput screening. Poor aqueous solubility of these lipophilic compounds can drastically affect the dissolution rate and subsequently the drug absorbed in the systemic circulation, imposing a significant burden of time and money during drug development process. Various pre-formulation and formulation strategies have been applied in the past that can improve the aqueous solubility of lipophilic compounds by manipulating either the crystal lattice properties or the activity coefficient of a solute in solution or both, if possible. However, despite various strategies available in the armor of formulation scientist, solubility issue still remains an overriding problem in the drug development process. It is perhaps due to the insufficient conceptual understanding of solubility and dissolution phenomenon that hinders the judgment in selecting suitable strategy for improving aqueous solubility and/or dissolution rate. This article, therefore, focuses on (i) revisiting the theoretical and mathematical concepts associated with solubility and dissolution, (ii) their application in making rationale decision for selecting suitable pre-formulation and formulation strategies and (iii) the relevant research performed in this field in past decade.

Formation of itraconazole-succinic acid cocrystals by gas antisolvent cocrystallization

Cocrystals of itraconazole, an antifungal drug with poor bioavailability, and succinic acid, a water-soluble dicarboxylic acid, were formed by gas antisolvent (GAS) cocrystallization using pressurized CO(2) to improve itraconazole dissolution. In this study, itraconazole and succinic acid were simultaneously dissolved in a liquid solvent, tetrahydrofuran, at ambient conditions. The solution was then pressurized with CO(2), which decreased the solvating power of tetrahydrofuran and caused crystallization of itraconazole-succinic acid cocrystals. The cocrystals prepared by GAS cocrystallization were compared to those produced using a traditional liquid antisolvent, n-heptane, for crystallinity, chemical structure, thermal behavior, size and surface morphology, potential clinical relevance, and stability. Powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy analyses showed that itraconazole-succinic acid cocrystals with physical and chemical properties similar to cocrystals produced using a traditional liquid antisolvent technique can be prepared by CO(2) antisolvent cocrystallization. The dissolution profile of itraconazole was significantly enhanced through GAS cocrystallization with succinic acid, achieving over 90% dissolution in less than 2 h. The cocrystals appeared stable against thermal stress for up to 4 weeks under accelerated stability conditions, showing only moderate decreases in their degree of crystallinity but no change in their crystalline structure. This study shows the utility of an itraconazole-succinic acid cocrystal for improving itraconazole bioavailability while also demonstrating the potential for CO(2) to replace traditional liquid antisolvents in cocrystal preparation, thus making cocrystal production more environmentally benign and scale-up more feasible.