Combination of co-crystal and nanocrystal techniques to improve the solubility and dissolution rate of poorly soluble drugs

Enhancing the solubility and bioavailability of itraconazole through pharmaceutical cocrystallization: A promising strategy for drug formulation

Itraconazole, a potent antifungal agent, is classified as a Biopharmaceutics Classification System (BCS) Class II drug, exhibiting high permeability but poor aqueous solubility, which significantly limits its bioavailability and therapeutic efficacy. Conventional solubility enhancement techniques such as salt formation, particle size reduction, and encapsulation have shown limited success due to the drug's non-ionizable nature and pH-dependent solubility. Cocrystallization has emerged as a promising pharmaceutical strategy to address these limitations by modifying the crystal lattice structure through non-covalent interactions with pharmaceutically acceptable co-formers. This study explores the formulation of Itraconazole cocrystals with various co-formers to enhance its solubility, dissolution rate, and micromeritic properties, thereby improving its processability in solid dosage forms. The optimized cocrystal formulation (B16) demonstrated a 2.4-fold increase in solubility in 0.1 N HCl (60.47 ± 2.7 µg/mL) and a 25.77-fold increase in phosphate buffer (pH 6.8, 60.57 ± 5.64 µg/mL) compared to pure Itraconazole. The dissolution rate was also significantly improved, with 40.12% drug release in 120 minutes in acidic medium, compared to 32.65% for pure Itraconazole. Furthermore, pharmacokinetic studies in rats revealed a 2.8-fold increase in AUC (3717.58 ng·h/mL) and a Cmax of 206.86 ng/mL, compared to 88.06 ng/mL for the pure drug. The study further examines the industrial feasibility of cocrystallization as an innovative approach for optimizing poorly soluble drugs in commercial formulations. The results highlight the potential of cocrystal technology in overcoming formulation challenges and advancing the development of more effective and patient-friendly antifungal therapies.

Development and Evaluation of Fluconazole Co-Crystal for Improved Solubility and Mechanical Properties

Background: Fluconazole (FLZ) is a broad-spectrum anti-fungal drug presenting poor flowability, mechanical properties, and limited aqueous solubility. These issues pose challenges for the handling and manufacturing of dosage forms of FLZ. The current research aimed to develop fluconazole co-crystal (CC) for improving its aqueous solubility, flowability, and mechanical properties. (2) Methods: The fluconazole benzoic acid (FLZ-BA) co-crystal was prepared using the solvent evaporation technique. The prepared co-crystal was characterized for drug content, solubility, anti-fungal activity, dissolution, and stability. DSC (Differential Scanning Calorimetry), PXRD (Powder X-Ray Diffraction), SEM (Scanning Electron Microscopy), and FTIR (Fourier Transmission Infrared) spectroscopy were carried out to confirm the co-crystal formation. The co-crystal was further evaluated for their flow characteristics and mechanical properties via CTC (compressibility, tabletability, and compactibility), Heckel, and Kawakita analysis. (3) Results: The CC showed 69.51% drug content and 13-fold greater aqueous solubility than pure FLZ. The DSC thermogram showed a sharp endothermic peak between the parent components, a distinct PXRD pattern was observed, and the SEM analysis revealed a different morphology, confirming the formation of co-crystal (new crystalline form). The CC showed immediate drug release and was found to more stable, and less hygroscopic than FLZ alone. The CC revealed better flowability, tabletability (tensile strength), compressibility, and compactibility. Moreover, Heckel and Kawakita analysis indicated the co-crystal to deform plastically, favoring improved compression. (4) Conclusions: The immediate drug release capabilities, improved hygroscopic stability, solubility, better antifungal activity, and flowability make FLZ-BA co-crystal a suitable candidate for the preparation of an immediate drug release dosage form. The study also revealed the application of co-crystal for improving the flowability and mechanical properties.

Preparation and characterization of andrographolide nano-cocrystals using hummer acoustic resonance technology

Andrographolide (AG) is a diterpene lactone with significant anti-inflammatory and antitumor activities. However, the poor water solubility limits its clinical application. An andrographolide-salicylic acid (AG-SLA) nano-cocrystal delivery system was rapidly developed using hummer acoustic resonance (HAR) technology in this research. The formulation of the AG-SLA nano-cocrystal suspension and the process parameters for HAR technology were optimized in a high-throughput manner, with SDS-Tween 80 as the optimal composite stabilizer. Nano-cocrystal suspension of AG-SLA with an average particle size of 190 nm were successfully prepared, and then the optimal formulation were tenfold scaled up. Freeze-drying was adopted to solidify the nano-cocrystal and improve its stability. Various analytical techniques were used to characterize the particle size and solid state of the nano-cocrystals. The high-energy input from the HAR instrument induced partial amorphization of the nano-cocrystals, as confirmed by PXRD and DSC analyses. Saturation solubility experiments demonstrated that the solubility in pH 1.2 hydrochloric acid buffer and pH 6.8 phosphate buffer increased by 5.74 times and 6.82 times, respectively, compared to raw AG. In vitro dissolution tests indicated that the cumulative release over 120 min in pH 1.2 hydrochloric acid buffer and pH 6.8 phosphate buffer increased by 1.60 times and 1.88 times, respectively, compared to raw AG.

Optimization of Glyburide-loaded Nanosuspensions via Ball Milling and Homogenization Techniques: A Central Composite Design Approach for Enhanced Solubility

INTRODUCTION

Glyburide is a drug for the treatment of diabetes mellitus and has a potential effect on Alzheimer's disease. It is also a BCS Class II drug with low solubility and low permeability. Developing a nanosuspension formulation and increasing the solubility and dissolution rate of glyburide is required to overcome this challenge.

METHODS

Thus, the goal of this work was to create glyburide nanosuspensions by ball milling and homogenizing glyburide to increase its solubility and rate of dissolution. To achieve this, the nanosuspension formulation was optimized using a central composite design. Zeta potential, particle size distribution and solubility were selected by way of dependent variables, and ball milling time, homogenization cycles, and Pluronic F-127/glyburide ratio were chosen as independent variables. Glyburide nanosuspensions were obtained with a particle size of 244.6 ± 2.685 nm. In vitro release and solubility studies were conducted following optimization.

RESULTS

The saturation solubility of glyburide was nearly doubled as a result of the nanocrystal formation. X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and fourier-transform infrared spectroscopy (FT-IR) were used to assess the nanosuspension. SEM images confirmed that the nanocrystal formation process was successful. Glyburide and the excipients have no incompatibilities, their physical states have not changed, and the preparation method has not affected the stability of glyburide, according to DCS, XRD, and FT-IR analyses.

CONCLUSION

These studies indicated that a combination of ball milling and homogenization techniques significantly enhanced the solubility of glyburide and its release from the formulation. Consequently, this approach can be applied to formulations characterized by low absorption and limited bioavailability.

Cocrystallization Enables Ensitrelvir to Overcome Anomalous Low Solubility Caused by Strong Intermolecular Interactions between Triazine-Triazole Groups in Stable Crystal Form

Ensitrelvir is a nonpeptide 3CL protease inhibitor used for coronavirus disease 2019 treatment. Four crystalline forms of ensitrelvir, metastable (Form I), acetonate (Form II), stable (Form III), and hydrate (Form IV), have been analyzed as pharmaceutical crystals. Their rank order of solubility is Form I > IV > III. Form III is the stable crystal with a significantly lower solubility than that predicted from its log P value of 2.7. Here, single-crystal structural analysis revealed strong intermolecular interactions between the triazine (acidic) and triazole (basic) groups of Form III not Forms I and IV. Multicomponent crystals were also designed to improve the solubility by altering the intermolecular interactions in Form III. Slurry conversion with equal molar ratios of ensitrelvir and fumaric acid successfully induced the formation of a novel cocrystal (Form V). Fumaric acid inhibited the triazine-triazole interactions, and dissolution of Form V was approximately 8- and 13-fold higher than that of Form III in pH 1.2 and 6.8 media, respectively. Furthermore, Form V exhibited an approximately 16-fold higher flux value than that of Form III. Therefore, alterations in intermolecular interactions via cocrystallization significantly enhance the dissolution and permeation of ensitrelvir.

Rebamipide nanocrystal with improved physicomechanical properties and its assessment through bio-mimicking 3D intestinal permeability model

This study investigated the formulation and characterization of rebamipide nanocrystals (REB-NCs) to enhance the solubility and permeability of rebamipide, an anti-ulcer medication known for its low aqueous solubility and permeability, classified as BCS class IV. Employing high-pressure homogenization and wet milling techniques, we successfully achieved nanonization of rebamipide, resulting in stable nanosuspensions that were subsequently freeze-dried to produce REB-NCs with an average particle size of 223 nm. Comprehensive characterization techniques, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) confirmed the crystalline nature of the nanocrystals and their compatibility with the selected excipients. The saturation solubility study revealed a remarkable three-fold enhancement in PBS pH 7.4 compared to rebamipide API, indicating the effectiveness of the nanocrystal formulation in improving drug solubility. Furthermore, 3D in-vitro permeability assessments conducted on Caco-2 cell monolayers demonstrated an noticeable increase in the permeability of REB-NCs relative to the pure active pharmaceutical ingredient (API), highlighting the promise of this formulation to enhance drug absorption. The dissolution profile of the nanocrystal tablets exhibited immediate release characteristics, significantly outperforming conventional formulations in terms of the dissolution rate. This research underscores the potential of nanomilling as a scalable, environment-friendly, and less toxic approach to significantly enhance the bioavailability of rebamipide. By addressing the challenges associated with the solubility and permeability of poorly water-soluble drugs, our outcome offers insightful information into developing efficient nanomedicine strategies for enhancing therapeutic outcomes.

Two Novel Hydrate Salts of Norfloxacin with Phenolic Acids and Their Physicochemical Properties

Norfloxacin (NORF) is a broad-spectrum quinolone that is widely utilized for the treatment of various bacterial infections and is considered one of the most commonly used fluoroquinolone antibiotics. However, NORF's clinical utility is limited by its poor water solubility and relatively low oral bioavailability. This study presents an optimization and synergistic enhancement approach through salt/co-crystal, aiming to maximize the biopharmaceutical properties of NORF with the use of phenolic acid. Following this strategy, two new hydrate salts of NORF with phenolic acid, namely, NORF-3,5-DBA hydrate (salt 1) and NORF-VA hydrate (salt 2), were prepared and systematically confirmed. Two hydrate salts were produced by means of the slow evaporation crystallization method, and the structures were determined through single-crystal X-ray diffraction (SCXRD). Additionally, powder X-ray diffraction (PXRD), Fourier-transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and high-performance liquid chromatography (HPLC) were applied to analyze the features of the two salts. The experimental results indicated that the formation of the two salts could enhance the solubility and improve the release behavior of NORF. Interestingly, the physicochemical properties of NORF were significantly improved as a result, leading to an enhancement in its antibacterial activity. This was demonstrated by the enhanced inhibition of bacterial strains and the lower minimum inhibitory concentration values.

Recent developments in the use of nanocrystals to improve bioavailability of APIs

Nanocrystals refer to materials with at least one dimension smaller than 100 nm, composing of atoms arranged in single crystals or polycrystals. Nanocrystals have significant research value as they offer unique advantages over conventional pharmaceutical formulations, such as high bioavailability, enhanced targeting selectivity and controlled release ability and are therefore suitable for the delivery of a wide range of drugs such as insoluble drugs, antitumor drugs and genetic drugs with broad application prospects. In recent years, research on nanocrystals has been progressively refined and new products have been launched or entered the clinical phase of studies. However, issues such as safety and stability still stand that need to be addressed for further development of nanocrystal formulations, and significant gaps do exist in research in various fields in this pharmaceutical arena. This paper presents a systematic overview of the advanced development of nanocrystals, ranging from the preparation approaches of nanocrystals with which the bioavailability of poorly water-soluble drugs is improved, critical properties of nanocrystals and associated characterization techniques, the recent development of nanocrystals with different administration routes, the advantages and associated limitations of nanocrystal formulations, the mechanisms of physical instability, and the enhanced dissolution performance, to the future perspectives, with a final view to shed more light on the future development of nanocrystals as a means of optimizing the bioavailability of drug candidates. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Nanocrystal-chitosan particles for intra-articular delivery of disease-modifying osteoarthritis drugs

Osteoarthritis is the most common chronic joint disease and a major health care concern due to the lack of efficient treatments. This is mainly related to the local and degenerative nature of this disease. Kartogenin was recently reported as a disease-modifying osteoarthritis drug that promotes cartilage repair, but its therapeutic effect is impeded by its very low solubility. Therefore, we designed a unique nanocrystal-chitosan particle intra-articular delivery system for osteoarthritis treatment that merges the following formulation techniques: nanosize reduction of a drug by wet milling and spray drying. The intermediate formulation (kartogenin nanocrystals) increased the solubility and dissolution rates of kartogenin. The final drug delivery system consisted of an easily resuspendable and ready-to-use microsphere powder for intra-articular injection. Positively charged chitosan microspheres with a median size of approximately 10 µm acted as a mothership drug delivery system for kartogenin nanocrystals in a simulated intra-articular injection. The microspheres showed suitable stability and a controlled release profile in synovial fluid and were nontoxic in human synoviocytes. The cartilage retention skills of the microspheres were also explored ex vivo using cartilage. This drug delivery system shows promise for advancement to preclinical stages in osteoarthritis therapy and scale-up production.

Herpetetrone nanosuspensions enhance drug solubility and bioavailability to improve anti-hepatic fibrosis effects

The aim of this study was to enhance the dissolution rate and oral bioavailability of herpetetrone (HPT) by preparing nanosuspensions (NSs) and evaluate the changes in its anti-hepatic fibrosis effect. Herpetetrone nanosuspension (HPT-NS) was prepared using the ultrasound-precipitation technique, and characterised on the basis of mean diameter, zeta potential (ZP), encapsulation efficiency percent (EE%), scanning electron microscopy (SEM), and X-ray powder diffraction (XRPD). In addition, the pharmacokinetics and anti-hepatic fibrosis activity were evaluated. HPT-NS prepared with the optimised formulation was found to be spherical with mean diameter of 177.48 ± 6.13 nm, polydispersity index (PDI) of 0.108 ± 0.002 and ZP of -17.28 ± 2.02 mV. The EE (m/m, %) was 83.25 ± 0.27. XRPD analyses confirmed that the amorphous state of HPT in HPT-NS remained unchanged. The dissolution rate of HPT-NS was significantly higher than that of HPT coarse suspensions (HPT-CSs). Following oral administration, Cmax and AUC0-t of HPT-NS showed a significant increase (p < 0.05). In vitro, HPT inhibited the proliferation of HSC-T6 cells and induced apoptosis by up-regulating the expression of Bax proteins and down-regulating the expression of Bcl-2 and TGF-β1 proteins. Compared with HPT-CS, HPT-NS exhibited a more pronounced anti-fibrotic effect. HPT-NS, as a new drug formulation designed to improve the solubility and bioavailability of the drug, shows promising potential in enhancing the anti-liver fibrosis effect.

Preparation of Nanosized Pharmaceutical Formulations by Dual Centrifugation

Dual centrifugation (DC) is an innovative in-vial homogenization and in-vial nanomilling technique that has been in use for the preparation of liposomes for more than one decade. Since then, DC has continuously been developed for preparing various liposomes and other lipid nanoparticles including emulsions and solid lipid nanoparticles (SLNs) as well as polymersomes and nanocrystals. Improvements in equipment technology have been achieved over the past decade, so that DC is now on its way to becoming the quasi-standard for the simple, fast, and aseptic production of lipid nanoparticles and nanocrystals in small and medium batch sizes, including the possibility of simple and fast formulation screening or bedside preparations of therapeutic nanoparticles. More than 68 publications in which DC was used to produce nanoparticles have appeared since then, justifying an initial review of the use of DC for pharmaceutical nanotechnology.

Nanosuspensions technology as a master key for nature products drug delivery and In vivo fate

The drug nanosuspensions is a universal formulation approach for improved drug delivery of hydrophobic drugs and one the most promising approaches for increasing the biopharmaceutical performance of poorly water-soluble drug substances, especially for nature products. This review aimed to summarize the nanosuspensions preparation approaches and the main technological difficulties encountered in nanosuspensions development, such as guidelines for stabilizers screening, in vivo fate of the intravenously administrated nanosuspensions, and how to realize the intravenously target delivery was reviewed. Furthermore, challenges of nanosuspensions for the nature products delivery also was discussed and commented. Therefore, it hoped to provide reference and assistance for the nanosuspensions production, stabilizers usage, and predictability of in vivo fate and controllability of targeting delivery of the nature products nanosuspensions.

A SWOT analysis of nano co-crystals in drug delivery: present outlook and future perspectives

The formulation of poorly soluble drugs is an intractable challenge in the field of drug design, development and delivery. This is particularly problematic for molecules that exhibit poor solubility in both organic and aqueous media. Usually, this is difficult to resolve using conventional formulation strategies and has resulted in many potential drug candidates not progressing beyond early stage development. Furthermore, some drug candidates are abandoned due to toxicity or have an undesirable biopharmaceutical profile. In many instances drug candidates do not exhibit desirable processing characteristics to be manufactured at scale. Nanocrystals and co-crystals, are progressive approaches in crystal engineering that can solve some of these limitations. While these techniques are relatively facile, they also require optimisation. Combining crystallography with nanoscience can yield nano co-crystals that feature the benefits of both fields, resulting in additive or synergistic effects to drug discovery and development. Nano co-crystals as drug delivery systems can potentially improve drug bioavailability and reduce the side-effects and pill burden of many drug candidates that require chronic dosing as part of treatment regimens. In addition, nano co-crystals are carrier-free colloidal drug delivery systems with particle sizes ranging between 100 and 1000 nm comprising a drug molecule, a co-former and a viable drug delivery strategy for poorly soluble drugs. They are simple to prepare and have broad applicability. In this article, the strengths, weaknesses, opportunities and threats to the use of nano co-crystals are reviewed and a concise incursion into the salient aspects of nano co-crystals is undertaken.

The antisolvent coprecipitation method for enhanced bioavailability of poorly water-soluble drugs

In recent years, poorly water-soluble drug candidates in the drug development pipeline have been a challenging issue for the pharmaceutical industry. Many delivery systems such as nanocrystals, cocrystals, nanoparticles, and amorphous solid dispersions (ASDs) have been developed to overcome these problems. A large number of methods are utilized to realize the above delivery systems. Among all the preparation methods, the antisolvent coprecipitation method is a relatively simple, cost-effective method, offering many advantages over conventional methods. An overview of recent developments for each solubility enhancement approach using the antisolvent coprecipitation method is presented. This current review details a comprehensive overview of the antisolvent coprecipitation process and its properties, as well as the fundamentals for enhancing the solubility and bioavailability of poorly water-soluble drugs by nanotization, polymorph control with polymers and/or surfactants. Furthermore, this review also presents insights into the factors affecting the antisolvent coprecipitation process.