Crystal engineering of active pharmaceutical ingredients to improve solubility and dissolution rates

Drug Crystal Precipitation in Biorelevant Bicarbonate Buffer: A Well-Controlled Comparative Study with Phosphate Buffer

The purpose of the present study was to clarify whether the precipitation profile of a drug in bicarbonate buffer (BCB) may differ from that in phosphate buffer (PPB) by a well-controlled comparative study. The precipitation profiles of structurally diverse poorly soluble drugs in BCB and PPB were evaluated by a pH-shift precipitation test or a solvent-shift precipitation test (seven weak acid drugs (pKa: 4.2 to 7.5), six weak base drugs (pKa: 4.8 to 8.4), one unionizable drug, and one zwitterionic drug). To focus on crystal precipitation processes, each ionizable drug was first completely dissolved in an HCl (pH 3.0) or NaOH (pH 11.0) aqueous solution (450 mL, 50 rpm, 37 °C). A 10-fold concentrated buffer solution (50 mL) was then added to shift the pH value to 6.5 to initiate precipitation (final volume: 500 mL, buffer capacity (β): 4.4 mM/ΔpH (BCB: 10 mM or PPB: 8 mM), ionic strength (I): 0.14 M (adjusted by NaCl)). The pH, β, and I values were set to be relevant to the physiology of the small intestine. For an unionizable drug, a solvent-shift method was used (1/100 dilution). To maintain the pH value of BCB, a floating lid was used to avoid the loss of CO2. The floating lid was applied also to PPB to precisely align the experimental conditions between BCB and PPB. The solid form of the precipitants was identified by powder X-ray diffraction and differential scanning microscopy. The precipitation of weak acids (pKa ≤ 5.1) and weak bases (pKa ≥ 7.3) was found to be slower in BCB than in PPB. In contrast, the precipitation profiles in BCB and PPB were similar for less ionizable or nonionizable drugs at pH 6.5. The final pH values of the bulk phase were pH 6.5 ± 0.1 after the precipitation tests in all cases. All precipitates were in their respective free forms. The precipitation of ionizable weak acids and bases was slower in BCB than in PPB. The surface pH of precipitating particles may have differed between BCB and PPB due to the slow hydration process of CO2 specific to BCB. Since BCB is a physiological buffer in the small intestine, it should be considered as an option for precipitation studies of ionizable weak acids and bases.

Spherical Crystallization Based on Liquid-Liquid Phase Separation in a Reverse Antisolvent Crystallization Process

Vanillin crystals undergo needle-like morphology that results in poor flowability, crystal breakage, and low packing density. The spherical crystallization technology can produce particles with improved flowability and stability. A reverse antisolvent crystallization based on liquid-liquid phase separation is proposed in this work to produce vanillin spherical agglomerates. Hansen Solubility Parameters are applied to explain the liquid-liquid phase separation (LLPS) phenomenon. The Pixact Crystallization Monitoring system is applied to in-situ monitor the whole process. A six-step spherical crystallization mechanism is revealed based on the recorded photos, including the generation of oil droplets, nucleation inside oil droplets, the coalescence and split of oil droplets, crystal growth and agglomeration, breakage of oil droplets, and attrition of agglomerates. Different working conditions are tested to explore the best operation parameters and a frequency-conversion stirring strategy is proposed to improve the production of spherical crystals.

Analysis of the Dissolution Behavior of Theophylline and Its Cocrystal Using ATR-FTIR Spectroscopic Imaging

Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic imaging is a powerful tool to visualize the distribution of components, and it has been used to analyze drug release from tablets. In this work, ATR-FTIR spectroscopic imaging was applied for observing the dissolution of molecular crystals from tablet compacts. The IR spectra provided chemically specific information about the transformation of crystal structures during the dissolution experiments. Theophylline (TPL) anhydrate and its cocrystals were used as model systems of molecular crystals. The IR spectra during the dissolution of TPL revealed information about the crystal structure of TPL, which transformed from anhydrate to monohydrate in water. During a dissolution test of a model cocrystal system, it was suggested that an active pharmaceutical ingredient (API) and a coformer were dissolved in water simultaneously. The IR spectra that were acquired during the dissolution of a cocrystal tablet showed new spectral bands attributed to the API after 5 min. This suggested that the precipitation of API was observed during the dissolution experiment. Measurements from ATR-FTIR spectroscopic imaging can visualize the drug release from the tablet and determine the transformation of molecular crystals during their dissolution. These results will have an impact on clarifying the dissolution mechanism of molecular crystals.

Efficient Screening of Pharmaceutical Cocrystals by Microspacing In-Air Sublimation

Cocrystal screening and single-crystal growth remain the primary obstacles in the development of pharmaceutical cocrystals. Here, we present a new approach for cocrystal screening, microspacing in-air sublimation (MAS), to obtain new cocrystals and grow high-quality single crystals of cocrystals within tens of minutes. The method possesses the advantages of strong designable ability of devices, user-friendly control, and compatibility with materials, especially for the thermolabile molecules. A novel drug-drug cocrystal of favipiravir (FPV) with salicylamide (SAA) was first discovered by this method, which shows improved physiochemical properties. Furthermore, this method proved effective in cultivating single crystals of FPV-isonicotinamide (FPV-INIA), FPV-urea, FPV-nicotinamide (FPV-NIA), and FPV-tromethamine (FPV-Tro) cocrystals, and the structures of these cocrystals were determined for the first time. By adjusting the growth temperature and growth distance precisely, we also achieved single crystals of 10 different paracetamol (PCA) cocrystals and piracetam (PIR) cocrystals, which underscores the versatility and efficiency of this method in pharmaceutical cocrystal screening.

Co-Processed Crystalline Solids of Ivermectin with Span® 60 as Solubility Enhancers of Ivermectin in Natural Oils

Despite being discovered over five decades ago, little is still known about ivermectin. Ivermectin has several physico-chemical properties that can result in it having poor bioavailability. In this study, polymorphic and co-crystal screening was used to see if such solid-state modifications can improve the oil solubility of ivermectin. Span® 60, a lipophilic non-ionic surfactant, was chosen as co-former. The rationale behind attempting to improve oil solubility was to use ivermectin in future topical and transdermal preparations to treat a range of skin conditions like scabies and head lice. Physical mixtures were also prepared in the same molar ratios as the co-crystal candidates, to serve as controls. Solid-state characterization was performed using X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The FTIR spectra of the co-crystal candidates showed the presence of Span® 60's alkyl chain peaks, which were absent in the spectra of the physical mixtures. Due to the absence of single-crystal X-ray data, co-crystal formation could not be confirmed, and therefore these co-crystal candidates were referred to as co-processed crystalline solids. Following characterization, the solid-state forms, physical mixtures and ivermectin raw material were dissolved in natural penetration enhancers, i.e., avocado oil (AVO) and evening primrose oil (EPO). The co-processed solids showed increased oil solubility by up to 169% compared to ivermectin raw material. The results suggest that co-processing of ivermectin with Span® 60 can be used to increase its oil solubility and can be useful in the development of oil-based drug formulations.

Comprehensive Application of XFEL Microcrystallography for Challenging Targets in Various Organic Compounds

There is a growing demand for structure determination from small crystals, and the three-dimensional electron diffraction (3D ED) technique can be employed for this purpose. However, 3D ED has certain limitations related to the crystal thickness and data quality. We here present the application of serial X-ray crystallography (SX) with X-ray free electron lasers (XFELs) to small (a few μm or less) and thin (a few hundred nm or less) crystals of novel compounds dispersed on a substrate. For XFEL exposures, two-dimensional (2D) scanning of the substrate coupled with rotation enables highly efficient data collection. The recorded patterns can be successfully indexed using lattice parameters obtained through 3D ED. This approach is especially effective for challenging targets, including pharmaceuticals and organic materials that form preferentially oriented flat crystals in low-symmetry space groups. Some of these crystals have been difficult to solve or have yielded incomplete solutions using 3D ED. Our extensive analyses confirmed the superior quality of the SX data regardless of crystal orientations. Additionally, 2D scanning with XFEL pulses gives an overall distribution of the samples on the substrate, which can be useful for evaluating the properties of crystal grains and the quality of layered crystals. Therefore, this study demonstrates that XFEL crystallography has become a powerful tool for conducting structure studies of small crystals of organic compounds.

Mechanoresponsive Flexible Crystals

Flexible crystals have gained significant attention owing to their remarkable pliability, plasticity, and adaptability, making them highly popular in various research and application fields. The main challenges in developing flexible crystals lie in the rational design, preparation, and performance optimization of such crystals. Therefore, a comprehensive understanding of the fundamental origins of crystal flexibility is crucial for establishing evaluation criteria and design principles. This Perspective offers a retrospective analysis of the development of flexible crystals over the past two decades. It summarizes the elastic standards and possible plastic bending mechanisms tailored to diverse flexible crystals and analyzes the assessment of their theoretical basis and applicability. Meanwhile, the compatibility between crystal elasticity and plasticity has been discussed, unveiling the immense prospects of elastic/plastic crystals for applications in biomedicine, flexible electronic devices, and flexible optics. Furthermore, this Perspective presents state-of-the-art experimental avenues and analysis methods for investigating molecular interactions in molecular crystals, which is vital for the future exploration of the mechanisms of crystal flexibility.

Advancing Drug Delivery Paradigms: Polyvinyl Pyrolidone (PVP)-Based Amorphous Solid Dispersion for Enhanced Physicochemical Properties and Therapeutic Efficacy

BACKGROUND

The current challenge in drug development lies in addressing the physicochemical issues that lead to low drug effectiveness. Solubility, a crucial physicochemical parameter, greatly influences various biopharmaceutical aspects of a drug, including dissolution rate, absorption, and bioavailability. Amorphous solid dispersion (ASD) has emerged as a widely explored approach to enhance drug solubility.

OBJECTIVE

The objective of this review is to discuss and summarize the development of polyvinylpyrrolidone (PVP)-based amorphous solid dispersion in improving the physicochemical properties of drugs, with a focus on the use of PVP as a novel approach.

METHODOLOGY

This review was conducted by examining relevant journals obtained from databases such as Scopus, PubMed, and Google Scholar, since 2018. The inclusion and exclusion criteria were applied to select suitable articles.

RESULTS

This study demonstrated the versatility and efficacy of PVP in enhancing the solubility and bioavailability of poorly soluble drugs. Diverse preparation methods, including solvent evaporation, melt quenching, electrospinning, coprecipitation, and ball milling are discussed for the production of ASDs with tailored characteristics.

CONCLUSION

PVP-based ASDs could offer significant advantages in the formulation strategies, stability, and performance of poorly soluble drugs to enhance their overall bioavailability. The diverse methodologies and findings presented in this review will pave the way for further advancements in the development of effective and tailored amorphous solid dispersions.

Investigation into polymorphism within ethenzamide-ethylmalonic acid cocrystal using Raman and terahertz vibrational spectroscopy

Two cocrystal polymorphs of ethenzamide (ETZ) and ethylmalonic acid (EMA) were synthesized by solvent evaporation. Crystal structure analysis revealed that the main amide - carboxyl heterosynthon in ETZ-EMA cocrystal Form I and Form II are the same, but the crystal structure of these two polymorphs are different. Terahertz (THz) and Raman vibrational spectroscopy were used to characterize ETZ, EMA, ETZ-EMA cocrystal polymorph Form I and Form II respectively. The experimental results showed that ETZ, EMA, ETZ-EMA cocrystal Form I and ETZ-EMA cocrystal Form II exhibited completely different characteristic peaks. Both THz and Raman vibrational spectroscopy can be used to distinguish ETZ-EMA cocrystal Form I from Form II. Furthermore, the investigation of phase transition induced by temperature and solid-state grinding was also performed. In the temperature phase transition experiments, when the powder sample was heated to a temperature range of 80-82 °C, the metastable ETZ-EMA cocrystal Form I transformed into the more stable ETZ-EMA cocrystal Form II. Solid-state grinding analysis revealed that the results of the ETZ-EMA cocrystal polymorph synthesis in grinding experiments depended on the polarity of the solvents used. Grinding without solvent or with high polarity solvents tended to result in the stable ETZ-EMA cocrystal Form II. Moreover, the metastable ETZ-EMA cocrystal Form I would transform into Form II after further grinding process. These results demonstrate that THz and Raman vibrational spectroscopy have high sensitivity and accuracy in the detection of both cocrystal synthesis and cocrystal polymorph phase transitions.

Overview and thermodynamic modelling of deep eutectic solvents as co-solvents to enhance drug solubilities in water

The poor water solubility of active pharmaceutical ingredients (APIs) is a major challenge in the pharmaceutical industry. Co-solvents are sometimes added to enhance drug dissolution. A novel group of co-solvents, the Deep Eutectic Solvents (DES), have gained interest in the pharmaceutical field due to their good solvent power, biodegradability, sustainability, non-toxicity, and low cost. In this study, we first provide an overview of all the literature solubility studies involving a drug or API + water + DES, which can be a valuable list to some researchers. Then, we analyze these systems with focus on each individual drug/API and provide statistical information on each. A similar analysis is carried out with focus on the individual DESs. An investigation of the numeric values of the water-solubility enhancement by the different DESs for various drugs indicates that DESs are indeed effective co-solvents, with varying degrees of solubility enhancement, even up to 15-fold. This is strongly encouraging, indicating the need for further studies to find the most promising DESs for solubility enhancement. However, time-consuming and costly trial and error should be prevented by first screening, using theoretical-based or thermodynamic-based models. Based on this conclusion, the second part of the study is concerned with investigating and suggesting accurate thermodynamic approaches to tackle the phase equilibrium modeling of such systems. For this purpose, a large data bank was collected, consisting of 2009 solubility data of 25 different drugs/APIs mixed with water and 31 different DESs as co-solvents at various DES concentrations, over wide ranges of temperatures at atmospheric pressure. This data bank includes 107 DES + water + drug/API systems in total. The solubility data were then modeled according to the solid-liquid equilibrium framework, using the local composition activity coefficient models of NRTL, and UNIQUAC. The results showed acceptable behavior with respect to the experimental values and trends for all of the investigated systems, with AARD% values of 9.65 % and 14.08 % for the NRTL and UNIQUAC models, respectively. In general, the lower errors of NRTL, as well as its simpler calculation process and the requirement of fewer component parameters, suggest the priority of NRTL over UNIQUAC for use in this field.

ADMET and Solubility Analysis of New 5-Nitroisatine-Based Inhibitors of CDK2 Enzymes

The development of new substances with the ability to interact with a biological target is only the first stage in the process of the creation of new drugs. The 5-nitroisatin derivatives considered in this study are new inhibitors of cyclin-dependent kinase 2 (CDK2) intended for anticancer therapy. The research, carried out based on the ADMET (absorption, distribution, metabolism, excretion, toxicity) methods, allowed a basic assessment of the physicochemical parameters of the tested drugs to be made. The collected data clearly showed the good oral absorption, membrane permeability, and bioavailability of the tested substances. The analysis of the metabolite activity and toxicity of the tested drugs did not show any critical hazards in terms of the toxicity of the tested substances. The substances' low solubility in water meant that extended studies tested compounds were required, which helped to select solvents with a high dissolving capacity of the examined substances, such as DMSO or NMP. The use of aqueous binary mixtures based on these two solvents allowed a relatively high solubility with significantly reduced toxicity and environmental index compared to pure solvents to be maintained, which is important in the context of the search for green solvents for pharmaceutical use.

Saquinavir-Piperine Eutectic Mixture: Preparation, Characterization, and Dissolution Profile

The dissolution rate of the anti-HIV drug saquinavir base (SQV), a poorly water-soluble and extremely low absolute bioavailability drug, was improved through a eutectic mixture formation approach. A screening based on a liquid-assisted grinding technique was performed using a 1:1 molar ratio of the drug and the coformers sodium saccharinate, theobromine, nicotinic acid, nicotinamide, vanillin, vanillic acid, and piperine (PIP), followed by differential scanning calorimetry (DSC). Given that SQV-PIP was the only resulting eutectic system from the screening, both the binary phase and the Tammann diagrams were adapted to this system using DSC data of mixtures prepared from 0.1 to 1.0 molar ratios in order to determine the exact eutectic composition. The SQV-PIP system formed a eutectic at a composition of 0.6 and 0.40, respectively. Then, a solid-state characterization through DSC, powder X-ray diffraction (PXRD), including small-angle X-ray scattering (SAXS) measurements to explore the small-angle region in detail, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and a powder dissolution test were performed. The conventional PXRD analyses suggested that the eutectic mixture did not exhibit structural changes; however, the small-angle region explored through the SAXS instrument revealed a change in the crystal structure of one of their components. FT-IR spectra showed no molecular interaction in the solid state. Finally, the dissolution profile of SQV in the eutectic mixture was different from the dissolution of pure SQV. After 45 min, approximately 55% of the drug in the eutectic mixture was dissolved, while, for pure SQV, 42% dissolved within this time. Hence, this study concludes that the dissolution rate of SQV can be effectively improved through the approach of using PIP as a coformer.

Cocrystals Enhance Biopharmaceutical and Antimicrobial Properties of Norfloxacin

A solvate cocrystal of the antimicrobial norfloxacin (NFX) was formed by using isonicotinamide (INA) as a coformer with the solvent evaporation technique. The cocrystal formation was confirmed by performing solid-state characterization techniques. We evaluated the dissolution under supersaturated conditions and also the solubility at the vertex of triphasic domain of cocrystal and NFX in both water and Fasted-State Simulated Intestinal Fluid (FaSSIF). The antimicrobial activity was evaluated using the microdilution technique. The cocrystal showed 1.8 times higher dissolution than NFX in water at 60 min and 1.3 times higher in FaSSIF at 180 min in the kinetic study. The cocrystal also had an increase in solubility of 8.38 times in water and 6.41 times in FaSSIF. The biopharmaceutical properties of NFX with cocrystallization improved antimicrobial action, as shown in the results of minimum inhibitory concentration (MIC) and inhibitory concentrations of 50% (IC50%) and 90% (IC90%). This paper presents, for the first time, a more in-depth analysis of the cocrystal of NFX-INA concerning its dissolution, solubility, and antimicrobial activity. In all these criteria, the cocrystal obtained better results compared to the pure drug.

Recent Advances in Co-Former Screening and Formation Prediction of Multicomponent Solid Forms of Low Molecular Weight Drugs

Multicomponent solid forms of low molecular weight drugs, such as co-crystals, salts, and co-amorphous systems, are a result of the combination of an active pharmaceutical ingredient (API) with a pharmaceutically acceptable co-former. These solid forms can enhance the physicochemical and pharmacokinetic properties of APIs, making them increasingly interesting and important in recent decades. Nevertheless, predicting the formation of API multicomponent solid forms in the early stages of formulation development can be challenging, as it often requires significant time and resources. To address this, empirical and computational methods have been developed to help screen for potential co-formers more efficiently and accurately, thus reducing the number of laboratory experiments needed. This review provides a comprehensive overview of current screening and prediction methods for the formation of API multicomponent solid forms, covering both crystalline states (co-crystals and salts) and amorphous forms (co-amorphous). Furthermore, it discusses recent advances and emerging trends in prediction methods, with a particular focus on artificial intelligence.

Amorphous Solid Dispersion as Drug Delivery Vehicles in Cancer

Cancer treatment has improved over the past decades, but a major challenge lies in drug formulation, specifically for oral administration. Most anticancer drugs have poor water solubility which can affect their bioavailability. This causes suboptimal pharmacokinetic performance, resulting in limited efficacy and safety when administered orally. As a result, it is essential to develop a strategy to modify the solubility of anticancer drugs in oral formulations to improve their efficacy and safety. A promising approach that can be implemented is amorphous solid dispersion (ASD) which can enhance the aqueous solubility and bioavailability of poorly water-soluble drugs. The addition of a polymer can cause stability in the formulations and maintain a high supersaturation in bulk medium. Therefore, this study aimed to summarize and elucidate the mechanisms and impact of an amorphous solid dispersion system on cancer therapy. To gather relevant information, a comprehensive search was conducted using keywords such as "anticancer drug" and "amorphous solid dispersion" in the PubMed, Scopus, and Google Scholar databases. The review provides an overview and discussion of the issues related to the ASD system used to improve the bioavailability of anticancer drugs based on molecular pharmaceutics. A thorough understanding of anticancer drugs in this system at a molecular level is imperative for the rational design of the products.

Ternary Solid Dispersions: A Review of the Preparation, Characterization, Mechanism of Drug Release, and Physical Stability

The prevalence of active pharmaceutical ingredients (APIs) with low water solubility has experienced a significant increase in recent years. These APIs present challenges in formulation, particularly for oral dosage forms, despite their considerable therapeutic potential. Therefore, the improvement of solubility has become a major concern for pharmaceutical enterprises to increase the bioavailability of APIs. A promising formulation approach that can effectively improve the dissolution profile and the bioavailability of poorly water-soluble drugs is the utilization of amorphous systems. Numerous formulation methods have been developed to enhance poorly water-soluble drugs through amorphization systems, including co-amorphous formulations, amorphous solid dispersions (ASDs), and the use of mesoporous silica as a carrier. Furthermore, the successful enhancement of certain drugs with poor aqueous solubility through amorphization has led to their incorporation into various commercially available preparations, such as ASDs, where the crystalline structure of APIs is transformed into an amorphous state within a hydrophilic matrix. A novel approach, known as ternary solid dispersions (TSDs), has emerged to address the solubility and bioavailability challenges associated with amorphous drugs. Meanwhile, the introduction of a third component in the ASD and co-amorphous systems has demonstrated the potential to improve performance in terms of solubility, physical stability, and processability. This comprehensive review discusses the preparation and characterization of poorly water-soluble drugs in ternary solid dispersions and their mechanisms of drug release and physical stability.

Finding the Right Solvent: A Novel Screening Protocol for Identifying Environmentally Friendly and Cost-Effective Options for Benzenesulfonamide

This study investigated the solubility of benzenesulfonamide (BSA) as a model compound using experimental and computational methods. New experimental solubility data were collected in the solvents DMSO, DMF, 4FM, and their binary mixtures with water. The predictive model was constructed based on the best-performing regression models trained on available experimental data, and their hyperparameters were optimized using a newly developed Python code. To evaluate the models, a novel scoring function was formulated, considering not only the accuracy but also the bias-variance tradeoff through a learning curve analysis. An ensemble approach was adopted by selecting the top-performing regression models for test and validation subsets. The obtained model accurately back-calculated the experimental data and was used to predict the solubility of BSA in 2067 potential solvents. The analysis of the entire solvent space focused on the identification of solvents with high solubility, a low environmental impact, and affordability, leading to a refined list of potential candidates that meet all three requirements. The proposed procedure has general applicability and can significantly improve the quality and speed of experimental solvent screening.

Exploring the Solubility and Bioavailability of Sodium Salt and Its Free Acid Solid Dispersions of Dolutegravir

Amorphous salt solid dispersion (ASSD) of Dolutegravir amorphous salt (DSSD) was generated using quench cooling and compared to its Dolutegravir free acid solid dispersion (DFSD) to improve the solubility and bioavailability. Soluplus (SLP) was used as a polymeric carrier in both solid dispersions. The prepared DSSD and DFSD, physical mixtures, and individual compounds were characterized by employing DSC, XRPD, and FTIR to assess the formation of the single homogenous amorphous phase and the existence of intermolecular interactions. Partial crystallinity was observed for DSSD, unlike DFSD, which is completely amorphous. No intermolecular interactions were observed between the Dolutegravir sodium (DS)/Dolutegravir free acid (DF) and SLP from the FTIR spectra of DSSD and DFSD. Both DSSD and DFSD improved the solubility of Dolutegravir (DTG) to 5.7 and 4.54 folds compared to the pure forms. Similarly, drug release from DSSD and DFSD was 2 and 1.5 folds higher than that in the pure form, owing to the rapid dissolution of the drug from the formulations. The permeability of DSSD and DFSD was estimated using the dialysis membrane, which enhanced the DTG permeability. The improvement in in vitro studies was translated into in vivo pharmacokinetic profiles of DSSD and DFSD, where 4.0 and 5.6 folds, respectively, improved the C_max of DTG.

Synthesis and characterization of innovative resveratrol nanobelt-like particles and assessment of their bioactivity, antioxidative and antibacterial properties

Recently, many studies have shown various beneficial effects of polyphenol resveratrol (Res) on human health. The most important of these effects include cardioprotective, neuroprotective, anti-cancer, anti-inflammatory, osteoinductive, and anti-microbial effects. Resveratrol has cis and trans isoforms, with the trans isoform being more stable and biologically active. Despite the results of in vitro experiments, resveratrol has limited potential for application in vivo due to its poor water solubility, sensitivity to oxygen, light, and heat, rapid metabolism, and therefore low bioavailability. The possible solution to overcome these limitations could be the synthesis of resveratrol in nanoparticle form. Accordingly, in this study, we have developed a simple, green solvent/non-solvent physicochemical method to synthesize stable, uniform, carrier-free resveratrol nanobelt-like particles (ResNPs) for applications in tissue engineering. UV-visible spectroscopy (UV-Vis) was used to identify the trans isoform of ResNPs which remained stable for at least 63 days. The additional qualitative analysis was performed by Fourier transform infrared spectroscopy (FTIR), while X-ray diffraction (XRD) determined the monoclinic structure of resveratrol with a significant difference in the intensity of diffraction peaks between commercial and nano-belt form. The morphology of ResNPs was evaluated by optical microscopy and field-emission scanning electron microscope (FE-SEM) that revealed a uniform nanobelt-like structure with an individual thickness of less than 1 μm. Bioactivity was confirmed using Artemia salina in vivo toxicity assay, while 2,2-diphenyl-1-picrylhydrazylhydrate (DPPH) reduction assay showed the good antioxidative potential of concentrations of 100 μg/ml and lower. Microdilution assay on several reference strains and clinical isolates showed promising antibacterial potential on Staphylococci, with minimal inhibitory concentration (MIC) being 800 μg/ml. Bioactive glass-based scaffolds were coated with ResNPs and characterized to confirm coating potential. All of the above make these particles a promising bioactive, easy-to-handle component in various biomaterial formulations.

Phosphate buffer interferes dissolution of prazosin hydrochloride in compendial dissolution testing

The purpose of this study was to elucidate the lack of supersaturation behavior in the dissolution profile of prazosin hydrochloride (PRZ-HCl) in the compendial dissolution test. The equilibrium solubility was measured by a shake-flask method. Dissolution tests were performed by a compendial paddle method with a phosphate buffer solution (pH 6.8, 50 mM phosphate). The solid form of the residual particles was identified by Raman spectroscopy. In the pH range below 6.5, the equilibrium solubility in phosphate buffer was lower than that in the unbuffered solutions (pH adjusted by HCl and NaOH). Raman spectra showed that the residual solid was a phosphate salt of PRZ. In the pH range above 6.5, the pH-solubility profiles in the phosphate buffer solutions and the unbuffered solutions were the same. The residual solid was a PRZ freebase (PRZ-FB). In the dissolution test, PRZ-HCl particles first changed to a phosphate salt within 5 min, then gradually changed to PRZ-FB after several hours. Since the intestinal fluid is buffered by the bicarbonate system in vivo, the dissolution behavior in vivo may not be properly evaluated using a phosphate buffer solution. For drugs with a low phosphate solubility product, it is necessary to consider this aspect.

Cocrystal Synthesis through Crystal Structure Prediction

Crystal structure prediction (CSP) is an invaluable tool in the pharmaceutical industry because it allows to predict all the possible crystalline solid forms of small-molecule active pharmaceutical ingredients. We have used a CSP-based cocrystal prediction method to rank ten potential cocrystal coformers by the energy of the cocrystallization reaction with an antiviral drug candidate, MK-8876, and a triol process intermediate, 2-ethynylglyclerol. For MK-8876, the CSP-based cocrystal prediction was performed retrospectively and successfully predicted the maleic acid cocrystal as the most likely cocrystal to be observed. The triol is known to form two different cocrystals with 1,4-diazabicyclo[2.2.2]octane (DABCO), but a larger solid form landscape was desired. CSP-based cocrystal screening predicted the triol-DABCO cocrystal as rank one, while a triol-l-proline cocrystal was predicted as rank two. Computational finite-temperature corrections enabled determination of relative crystallization propensities of the triol-DABCO cocrystals with different stoichiometries and prediction of the triol-l-proline polymorphs in the free-energy landscape. The triol-l-proline cocrystal was obtained during subsequent targeted cocrystallization experiments and was found to exhibit an improved melting point and deliquescence behavior over the triol-free acid, which could be considered as an alternative solid form in the synthesis of islatravir.

Levocetirizine-Loaded Electrospun Fibers from Water-Soluble Polymers: Encapsulation and Drug Release

Electrospun fibers containing levocetirizine, a BCS III drug, were prepared from three water-soluble polymers, hydroxypropyl methylcellulose (HPMC), polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA). Fiber-spinning technology was optimized for each polymer separately. The polymers contained 10 wt% of the active component. An amorphous drug was homogeneously distributed within the fibers. The solubility of the drug in the polymers used was limited, with a maximum of 2.0 wt%, but it was very large in most of the solvents used for fiber spinning and in the dissolution media. The thickness of the fibers was uniform and the presence of the drug basically did not influence it at all. The fiber diameters were in the same range, although somewhat thinner fibers could be prepared from PVA than from the other two polymers. The results showed that the drug was amorphous in the fibers. Most of the drug was located within the fibers, probably as a separate phase; the encapsulation efficiency proved to be 80-90%. The kinetics of the drug release were evaluated quantitatively by the Noyes-Whitney model. The released drug was approximately the same for all the polymers under all conditions (pH), and it changed somewhere between 80 and 100%. The release rate depended both on the type of polymer and pH and varied between 0.1 and 0.9 min^-1. Consequently, the selection of the carrier polymer allowed for the adjustment of the release rate according to the requirements, thus justifying the use of electrospun fibers as carrier materials for levocetirizine.

Antisolvent Crystallization of Telmisartan Using Stainless-Steel Micromixing Membrane Contactors

Controlled continuous crystallization of the active pharmaceutical ingredient (API) telmisartan (TEL) has been conducted from TEL/DMSO solutions by antisolvent crystallization in deionized water using membrane micromixing contactors. The purpose of this work was to test stainless-steel membranes with ordered 10 μm pores spaced at 200 μm in a stirred-cell (batch, LDC-1) and crossflow (continuous, AXF-1) system for TEL formation. By controlling the feed flow rate of the API and solvent, through the membrane pores as well as the antisolvent flow, it was possible to tightly control the micromixing and with that to control the crystal nucleation and growth. Batch crystallization without the membrane resulted in an inhomogeneous crystallization process, giving a mixture of crystalline and amorphous TEL materials. The rate of crystallization was controlled with a higher DMSO content (4:1 DMSO/DI water), resulting in slower crystallization of the TEL material. Both membrane setups, stirred batch and the crossflow, yielded the amorphous TEL particles when deionized water was used, while a crystalline material was produced when a mixture of DI water and DMSO was used.

Preparation and characterization of naproxen solid dispersion using different hydrophilic carriers and in-vivo evaluation of its analgesic activity in mice

Background

Solid dispersion (SD) has been used conventionally as a successful technique for improving the dissolution profile and bioavailability of poorly water-soluble drugs. The aim of this study was to progress the dissolution rate and bioavailability of naproxen (BCS class II) by SD technique.

Materials & methods

In this study, hydrophilic carriers are used for preparing solid dispersion of naproxen by evaporation method. The prepared optimized SDNs were evaluated by in-vitro drug dissolution test, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The in-vivo analgesic effects tests of the optimized SDNs (SDN-2 and SDN-5) were performed by tail immersion method and writhing method.

Results

All the prepared SDNs exhibited a significant increase in the dissolution of naproxen compared to that of the pure drug. Among them, SDN-2 (the dispersion with sodium starch glycolate at 1:2 ratio of naproxen and sodium starch glycolate) and SDN-5 (using the combination of PEG-8000 and sodium starch glycolate with naproxen at 1:1:1 ratio) showed faster dissolution rate as compared to other solid dispersions (SDNs) and pure naproxen. SDN-2 showed 5.4 times better dissolution rate and SDN-5 depicted 6.5-fold increment of dissolution rate compared to pure naproxen drug. DSC, PXRD and SEM microscopy showed that the drugs crystallinity was decreased during the preparation process. FTIR study revealed that naproxen was stable in polymeric dispersions and there was no interaction among the drug and polymers. In writhing method, the percentage inhibition of the number of writhes showed significantly greater (p < 0.01), (p < 0.0001) analgesic activity for the higher dose treatment groups SDN-2(H), and SDN-5(H), respectively, when contrasted to the pure drug naproxen. For tail immersion test, there is increase in latency time at 90 min which is significantly greater (P < 0.01), (P < 0.05), (P < 0.01) for treatment groups SDN-2(H), SDN-5(L), and SDN-5(H), respectively that ultimately authenticates that the optimized SDNs (SDN-2, SDN-5) showed better analgesic activity in mice in comparison with the pure drug.

Conclusion

It can be concluded that dissolution of the naproxen could be improved by the making solid dispersion using sodium starch glycolate and/or combination of sodium starch glycolate and PEG 8000 due to the complete transformation of drug into amorphous form with the entire loss of crystallinity, as evidenced by DSC, PXRD, and SEM and also consequences the enhanced analgesic activity in mice.

Advancement in Solubilization Approaches: A Step towards Bioavailability Enhancement of Poorly Soluble Drugs

A drug's aqueous solubility is defined as the ability to dissolve in a particular solvent, and it is currently a major hurdle in bringing new drug molecules to the market. According to some estimates, up to 40% of commercialized products and 70-90% of drug candidates in the development stage are poorly soluble, which results in low bioavailability, diminished therapeutic effects, and dosage escalation. Because of this, solubility must be taken into consideration when developing and fabricating pharmaceutical products. To date, a number of approaches have been investigated to address the problem of poor solubility. This review article attempts to summarize several conventional methods utilized to increase the solubility of poorly soluble drugs. These methods include the principles of physical and chemical approaches such as particle size reduction, solid dispersion, supercritical fluid technology, cryogenic technology, inclusion complex formation techniques, and floating granules. It includes structural modification (i.e., prodrug, salt formation, co-crystallization, use of co-solvents, hydrotrophy, polymorphs, amorphous solid dispersions, and pH variation). Various nanotechnological approaches such as liposomes, nanoparticles, dendrimers, micelles, metal organic frameworks, nanogels, nanoemulsions, nanosuspension, carbon nanotubes, and so forth have also been widely investigated for solubility enhancement. All these approaches have brought forward the enhancement of the bioavailability of orally administered drugs by improving the solubility of poorly water-soluble drugs. However, the solubility issues have not been completely resolved, owing to several challenges associated with current approaches, such as reproducibility in large scale production. Considering that there is no universal approach for solving solubility issues, more research is needed to simplify the existing technologies, which could increase the number of commercially available products employing these techniques.

Exploring the Conformational Equilibrium of Mefenamic Acid Released from Silica Aerogels via NMR Analysis

This study examines the influence of mefenamic acid on the physical and chemical properties of silica aerogels, as well as its effect on the sorption characteristics of the composite material. Solid state magic angle spinning nuclear magnetic resonance (MAS NMR) and high-pressure ¹³C NMR kinetic studies were conducted to identify the presence of mefenamic acid and measure the kinetic rates of CO₂ sorption. Additionally, a high-pressure T₁-T₂ relaxation-relaxation correlation spectroscopy (RRCOSY) study was conducted to estimate the relative amount of mefenamic acid in the aerogel's pores, and a high-pressure nuclear Overhauser effect spectoscopy (NOESY) study was conducted to investigate the conformational preference of mefenamic acid released from the aerogel. The results indicate that mefenamic acid is affected by the chemical environment of the aerogel, altering the ratio of mefenamic acid conformers from 75% to 25% in its absence to 22% to 78% in the presence of aerogel.

Experimental and Theoretical Investigation of Hydrogen-Bonding Interactions in Cocrystals of Sulfaguanidine

Pharmaceutical cocrystals, a type of multicomponent crystalline material incorporating two or more molecular and/or ionic compounds connected by noncovalent interactions (such as hydrogen bonds, π-π interactions, and halogen bonds), are attracting increasing attention in crystal engineering. Sulfaguanidine (SGD), one of the most frequently used sulfonamide compounds, was chosen as a model compound in this work to further investigate the hydrogen bond interactions in cocrystals, since it possesses various hydrogen bond donor and acceptor sites. Five cocrystals of SGD, synthesized successfully by slurry and slow evaporation methods, were fully characterized by thermal analysis, X-ray techniques, and Fourier transform infrared spectroscopy. To gain insight into the nature of hydrogen-bonding interactions, theoretical calculations including the analysis of Hirshfeld surface, MEPS (molecular electrostatic potential surface), and QTAIM (quantum theory of atoms in molecules) were conducted. The results are a part of a systematic study of cocrystals of sulfonamides that aims to establish synthon hierarchies in cocrystals containing molecules with multiple hydrogen-bonding functional groups.

Needles to Spheres: Evaluation of inkjet printing as a particle shape enhancement tool

Active pharmaceutical ingredients (APIs) often reveal shapes challenging to process, e.g. acicular structures, and exhibit reduced bioavailability induced by slow dissolution rate. Leveraging the API particles' surface and bulk properties offers an attractive pathway to circumvent these challenges. Inkjet printing is an attractive processing technique able to tackle these limitations already in initial stages when little material is available, while particle properties are maintained over the entire production scale. Additionally, it is applicable to a wide range of formulations and offers the possibility of co-processing with a variety of excipients to improve the API's bioavailability. This study addresses the optimization of particle shapes for processability enhancement and demonstrates the successful application of inkjet printing to engineer spherical lacosamide particles, which are usually highly acicular. By optimizing the ink formulation, adapting the substrate-liquid interface and tailoring the heat transfer to the particle, spherical particles in the vicinity of 100 µm, with improved flow properties compared to the bulk material, were produced. Furthermore, the particle size was tailored reproducibly by adjusting the deposited ink volume per cycle and the number of printing cycles. Therefore, the present study shows a novel, reliable, scalable and economical strategy to overcome challenging particle morphologies by co-processing an API with suitable excipients.

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.

Rational Coformer Selection in the Development of 6-Propyl-2-thiouracil Pharmaceutical Cocrystals

Pharmaceutical multicomponent solids have proved to efficiently modulate the physicochemical properties of active pharmaceutical ingredients. In this context, polyphenols are interesting coformers for designing pharmaceutical cocrystals due to their wide safety profile and interesting antioxidant properties. The novel 6-propyl-2-thiouracil multicomponent solids have been obtained by mechanochemical synthesis and fully characterized by powder and single-crystal X-ray diffraction methods. The analysis of supramolecular synthons has been further performed with computational methods, with both results revealing a robust supramolecular organization influenced by the different positions of the hydroxyl groups within the polyphenolic coformers. All novel 6-propyl-2-thiouracil cocrystals show an enhanced solubility profile, but unfortunately, their thermodynamic stability in aqueous media is limited to 24 h.

Critical Analysis and Optimization of Stoichiometric Ratio of Drug-Coformer on Cocrystal Design: Molecular Docking, In Vitro and In Vivo Assessment

In this present research, an attempt has been made to address the influence of drug-coformer stoichiometric ratio on cocrystal design and its impact on improvement of solubility and dissolution, as well as bioavailability of poorly soluble telmisartan. The chemistry behind cocrystallization and the optimization of drug-coformer molar ratio were explored by the molecular docking approach, and theoretical were implemented practically to solve the solubility as well as bioavailability related issues of telmisartan. A new multicomponent solid form, i.e., cocrystal, was fabricated using different molar ratios of telmisartan and maleic acid, and characterized by SEM, DSC and XRD studies. The molecular docking study suggested that specific molar ratios of drug-coformer can successfully cluster with each other and form a specific geometry with favourable energy conformation to form cocrystals. Synthesized telmisartan-maleic acid cocrystals showed remarkable improvement in solubility and dissolution of telmisartan by 9.08-fold and 3.11-fold, respectively. A SEM study revealed the formation of cocrystals of telmisartan when treated with maleic acid. DSC and XRD studies also confirmed the conversion of crystalline telmisartan into its cocrystal state upon treating with maleic acid. Preclinical investigation revealed significant improvement in the efficacy of optimized cocrystals in terms of plasma drug concentration, indicating enhanced bioavailability through improved solubility as well as dissolution of telmisartan cocrystals. The present research concluded that molecular docking is an important path in selecting an appropriate stoichiometric ratio of telmisartan: maleic acid to form cocrystals and improve the solubility, dissolution, and bioavailability of poorly soluble telmisartan.

Cocrystals; basic concepts, properties and formation strategies

Cocrystallization is an old technique and remains the focus of several research groups working in the field of Chemistry and Pharmacy. This technique is basically in field for improving physicochemical properties of material which can be active pharmaceutical ingredients (APIs) or other chemicals with poor profile. So this review article has been presented in order to combine various concepts for scientists working in the field of chemistry, pharmacy or crystal engineering, also it was attempt to elaborate concepts belonging to crystal designing, their structures and applications. A handsome efforts have been made to bring scientists together working in different fields and to make chemistry easier for a pharmacist and pharmacy for chemists pertaining to cocrystals. Various aspects of chemicals being used as co-formers have been explored which predict the formation of co-crystals or molecular salts and even inorganic cocrystals.

Current Techniques of Water Solubility Improvement for Antioxidant Compounds and Their Correlation with Its Activity: Molecular Pharmaceutics

The aqueous solubility of a drug is important in the oral formulation because the drug can be absorbed from intestinal sites after being dissolved in the gastrointestinal fluid, leading to its bioavailability. Almost 80% of active pharmaceutical ingredients are poorly water-soluble, including antioxidant compounds. This makes antioxidant activity inefficient in preventing disease, particularly for orally administered formulations. Although several investigations have been carried out to improve the solubility of antioxidant compounds, there is still limited research fully discussing the subject. Therefore, this study aimed to provide an overview and discussion of the issues related to the methods that have been used to improve the solubility and activity of antioxidant compounds. Articles were found using the keywords "antioxidant" and "water solubility improvement" in the Scopus, PubMed, and Google Scholar databases. The selected articles were published within the last five years to ensure all information was up-to-date with the same objectives. The most popular methods of the strategies employed were solid dispersion, co-amorphous, and nanoparticle drug delivery systems, which were used to enhance the solubility of antioxidant compounds. These investigations produced impressive results, with a detailed discussion of the mechanism of improvement in the solubility and antioxidant activity of the compounds developed. This review shows that the strategies used to increase the solubility of antioxidant compounds successfully improved their antioxidant activity with enhanced free radical scavenging abilities.

XDM-corrected hybrid DFT with numerical atomic orbitals predicts molecular crystal lattice energies with unprecedented accuracy

Molecular crystals are important for many applications, including energetic materials, organic semiconductors, and the development and commercialization of pharmaceuticals. The exchange-hole dipole moment (XDM) dispersion model has shown good performance in the calculation of relative and absolute lattice energies of molecular crystals, although it has traditionally been applied in combination with plane-wave/pseudopotential approaches. This has limited XDM to use with semilocal functional approximations, which suffer from delocalization error and poor quality conformational energies, and to systems with a few hundreds of atoms at most due to unfavorable scaling. In this work, we combine XDM with numerical atomic orbitals, which enable the efficient use of XDM-corrected hybrid functionals for molecular crystals. We test the new XDM-corrected functionals for their ability to predict the lattice energies of molecular crystals for the X23 set and 13 ice phases, the latter being a particularly stringent test. A composite approach using a XDM-corrected, 25% hybrid functional based on B86bPBE achieves a mean absolute error of 0.48 kcal mol^-1 per molecule for the X23 set and 0.19 kcal mol^-1 for the total lattice energies of the ice phases, compared to recent diffusion Monte-Carlo data. These results make the new XDM-corrected hybrids not only far more computationally efficient than previous XDM implementations, but also the most accurate density-functional methods for molecular crystal lattice energies to date.

Preparation and Physiochemical Analysis of Novel Ciprofloxacin / Dicarboxylic Acid Salts

The crystal structures of four novel dicarboxylic acid salts of ciprofloxacin (CFX) with modified physicochemical properties, prepared by mechanochemical synthesis and solvent crystallization, are reported. A series of dicarboxylic acids of increasing molecular weight was chosen, predicted to interact via a carboxylic acid:secondary amine synthon. These were succinic (SA), glutaric (GA), adipic (AA) and pimelic (PA) acids (4, 5, 6, 7 carbon atoms respectively). Characterized by single crystal and powder X-ray diffraction, Fourier-Transform Infrared Spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy and aqueous solubility measurements, these salts showed distinct physicochemical properties relative to ciprofloxacin base. Searches of the Cambridge Structural Database (CSD) confirmed CFX-SA, CFX-GA, CFX-AA and CFX-PA to be novel crystal structures. Furthermore, the GA salt has substantially higher solubility than the widely available hydrochloride monohydrate salt (CFX-HCl·H₂O). CFX-SA, CFX-GA and CFX-AA showed minimum inhibitory concentration (MIC) of 0.008 g/L and CFX-PA showed MIC of 0.004 g/L. The prepared CFX salts retained antibacterial activity exhibiting equivalent antimicrobial activity to CFX-HCl·H₂O. These salts have positive implications for increasing the application of CFX beyond conventional oral formulations and highlight mechanochemical activation as suitable production method.

Nanosuspension: A Formulation Technology for Tackling the Poor Aqueous Solubility and Bioavailability of Poorly Soluble Drugs

The poor water solubility of numerous novel drug candidates presents significant challenges, particularly in terms of oral administration. This limitation can result in various undesirable clinical implications, such as inter-patient variability, poor bioavailability, difficulties in achieving a safe therapeutic index, increased costs, and potential risks of toxicity or inefficacy. Biopharmaceutics Classification System (BCS) class II drugs face particular hurdles due to their limited solubility in the aqueous media of the gastrointestinal tract. In such cases, parenteral administration is often employed as an alternative strategy. To address these challenges, nanosuspension techniques offer a promising solution for enhancing drug solubility and overcoming oral delivery obstacles. This technique has the potential to bridge the gap between drug discovery and preclinical use by resolving problematic solubility. This literature review has delved into contemporary nanosuspension preparation technologies and the incorporation of stabilizing ingredients within the formulation. Furthermore, the manuscript explores nanosuspension strategies for both oral and parenteral/other delivery routes, and separate discussions have been presented to establish a suitable flow that addresses the challenges and strategies relevant to each administration method.

[Solubilization of Poorly Water-soluble Drugs with Amphiphilic Phospholipid Polymers]

Most drug candidates developed in recent years are poorly water-soluble, which is a key challenge in pharmaceutical science. Various solubilization methods have been investigated thus far, most of which require solubilizers that provide a local hydrophobic environment wherein a drug can dissolve or induce interactions with drug molecules. We have focused on amphiphilic 2-methacryloyloxyethyl phosphoryl choline (MPC) polymers. In addition to the ease of molecular design of amphiphilic MPC polymers owing to their chemical structures, they have been reported to possess high biocompatibility in various biomaterial applications. Additionally, amphiphilic MPC polymers have been applied in the pharmaceutical field, especially in solubilization. We have qualitatively and quantitatively evaluated the effects of the chemical structure and physical properties of the solubilizer on the MPC polymers. In particular, MPC polymers with different chemical structures were designed and synthesized. The inner polarity and molecular mobility in the polymer aggregates were evaluated, indicating that the intrinsic properties reflect the chemical structure of the polymer. Additionally, amphiphilic MPC polymers were used to improve the solubility of poorly water-soluble drugs and as solid dispersion carriers, and they exhibited superior solubilizing abilities compared to a commonly used polymer. Furthermore, the solubility of biopharmaceuticals, such as peptides, was improved. It is possible to design and synthesize optimal structures based on the polarity of the hydrophobic environment and the intermolecular interaction with a drug. This research provides a unified interpretation of drugs and efficiently summarizes knowledge about drug development, which will facilitate the efficient and rapid development of drug formulations.

Technical and engineering considerations for designing therapeutics and delivery systems

The newly-emerged pathological conditions and increased rates of drug resistance necessitate application of the state-of-the-art technologies for accelerated discovery of the therapeutic candidates and obtaining comprehensive knowledge about their targets, action mechanisms, and interactions within the body including those between the receptors and drugs. Using the physics- and chemistry-based modern techniques for theranostic purposes, preparing smart carriers, local delivery of genes or drugs, and enhancing pharmaceutical bioavailability could be of great value against the hard-to-treat diseases and growing drug resistance. Besides the artificial intelligence- and quantum-based techniques, crystal engineering capable of designing new molecules with appropriate characteristics, improving the stability and bioavailability of poorly soluble drugs, and efficient carrier development could play a crucial role in manufacturing efficient pharmaceuticals and reducing the adverse events. In this context, identifying the structures and behaviors of crystals and predicting their characteristics are of great value. Electron diffraction by accelerated analysis of the chemicals and sensitivity to charge alterations, electromechanical tools for controlled delivery of therapeutics, mechatronics via fabrication of multi-functional smart products including the organ-on-chip devices for healthcare applications, and optomechatronics by overcoming the limitations of conventional biomedical techniques could address the unmet biomedical requirements and facilitate development of more effective theranostics with improved outcomes.

New salts of teriflunomide (TFM) - Single crystal X-ray and solid state NMR investigation

New salts of teriflunomide TFM (drug approved for Multiple Sclerosis treatment) with inorganic counterions: lithium (TFM_Li), sodium (TFM_Na), potassium (TFM_K), rubidium (TFM_Rb), caesium (TFM_Cs) and ammonium (TFM_NH₄) were prepared and investigated employing solid state NMR Spectroscopy, Powder X-ray Diffraction PXRD and Single Crystal X-ray Diffraction (SC XRD). Crystal and molecular structures of three salts: TFM_Na (CCDC: 2173257), TFM_Cs (CCDC: 2165288) and TFM_NH₄ (CCDC: 2165281) were determined and deposited. Compared to the native TFM, for all crystalline salt structures, a conformational change of the teriflunomide molecule involving about 180-degree rotation of the end group, forming an intramolecular hydrogen bond N-H⋯O is observed. By applying a complementary multi-technique approach, employing 1D and 2D solid state MAS NMR techniques, single and powder X-ray diffraction measurements, as well as the DFT-based GIPAW calculations of NMR chemical shifts for TFM_Na and TFM_Cs allowed to propose structural features of TFM_Li for which it was not possible to obtain adequate material for single crystal X-Ray measurement.

Progressive alignment of crystals: reproducible and efficient assessment of crystal structure similarity

During in silico crystal structure prediction of organic molecules, millions of candidate structures are often generated. These candidates must be compared to remove duplicates prior to further analysis (e.g. optimization with electronic structure methods) and ultimately compared with structures determined experimentally. The agreement of predicted and experimental structures forms the basis of evaluating the results from the Cambridge Crystallographic Data Centre (CCDC) blind assessment of crystal structure prediction, which further motivates the pursuit of rigorous alignments. Evaluating crystal structure packings using coordinate root-mean-square deviation (RMSD) for N molecules (or N asymmetric units) in a reproducible manner requires metrics to describe the shape of the compared molecular clusters to account for alternative approaches used to prioritize selection of molecules. Described here is a flexible algorithm called Progressive Alignment of Crystals (PAC) to evaluate crystal packing similarity using coordinate RMSD and introducing the radius of gyration (R _g) as a metric to quantify the shape of the superimposed clusters. It is shown that the absence of metrics to describe cluster shape adds ambiguity to the results of the CCDC blind assessments because it is not possible to determine whether the superposition algorithm has prioritized tightly packed molecular clusters (i.e. to minimize R _g) or prioritized reduced RMSD (i.e. via possibly elongated clusters with relatively larger R _g). For example, it is shown that when the PAC algorithm described here uses single linkage to prioritize molecules for inclusion in the superimposed clusters, the results are nearly identical to those calculated by the widely used program COMPACK. However, the lower R _g values obtained by the use of average linkage are favored for molecule prioritization because the resulting RMSDs more equally reflect the importance of packing along each dimension. It is shown that the PAC algorithm is faster than COMPACK when using a single process and its utility for biomolecular crystals is demonstrated. Finally, parallel scaling up to 64 processes in the open-source code Force Field X is presented.

Improvement of Oral Absorption of Poorly Water-Soluble Drugs by Solid Dispersions with Amphiphilic Phospholipid Polymer

Solid dispersions are one of methods for solubilizing water-insoluble drugs. To enhance the bioavailability, maintenance of the supersaturated state and absorption of the dissolved drug in the gastrointestinal tract are important. We designed and synthesized amphiphilic 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymers as carriers for solid dispersions and evaluated the dissolution behavior in test solutions with different pH and additives. Solid dispersion of troglitazone with amphiphilic MPC copolymers having both aromatic rings and urethane bonds in the side chains showed rapid dissolution and excellent supersaturation maintenance. It was indicated that the balance between the interactions with drug molecules and the water affinity of the polymer should be considered when carriers for solid dispersions are designed. In addition, cell membrane permeability of the solid dispersion with the amphiphilic MPC copolymer was evaluated by the Dissolution / Permeation system, which consists of two liquid chambers and a monolayer of epithelial cells that mimics the intestinal dissolution and permeation process. Further, blood concentration of the drug when solid dispersions were orally administered in mice was also evaluated. The cell membrane permeability and oral absorbability were significantly improved, compared to the solid dispersions with poly(N-vinylpyrrolidone) and suspension or solution of crystalline troglitazone.

Microfluidic Particle Engineering of Hydrophobic Drug with Eudragit E100─Bridging the Amorphous and Crystalline Gap

Co-processing active pharmaceutical ingredients (APIs) with excipients is a promising particle engineering technique to improve the API physical properties, which can lead to more robust downstream drug product manufacturing and improved drug product attributes. Excipients provide control over critical API attributes like particle size and solid-state outcomes. Eudragit E100 is a widely used polymeric excipient to modulate drug release. Being cationic, it is primarily employed as a precipitation inhibitor to stabilize amorphous solid dispersions. In this work, we demonstrate how co-processing of E100 with naproxen (NPX) (a model hydrophobic API) into monodisperse emulsions via droplet microfluidics followed by solidification via solvent evaporation allows the facile fabrication of compact, monodisperse, and spherical particles with an expanded range of solid-state outcomes spanning from amorphous to crystalline forms. Low E100 concentrations (≤26% w/w) yield crystalline microparticles with a stable NPX polymorph distributed uniformly across the matrix at a high drug loading (∼89% w/w). Structurally, E100 incorporation reduces the size of primary particles comprising the co-processed microparticles in comparison to neat API microparticles made using the same technique and the as-received API powder. This reduction in primary particle size translates into an increased internal porosity of the co-processed microparticles, with specific surface area and pore volume ∼9 times higher than the neat API microparticles. These E100-enabled structural modifications result in faster drug release in acidic media compared to neat API microparticles. Additionally, E100-NPX microparticles have a significantly improved flowability compared to neat API microparticles and as-received API powder. Overall, this study demonstrates a facile microfluidics-based co-processing method that broadly expands the range of solid-state outcomes obtainable with E100 as an excipient, with multiscale control over the key attributes and performance of hydrophobic API-laden microparticles.

New Saccharin Salt of Chlordiazepoxide: Structural and Physicochemical Examination

Since the formation of organic salts can improve the solubility, bioavailability, and stability of active pharmaceutical ingredients, the aim of this work was to prepare an organic salt of chlordiazepoxide with saccharin. To achieve this goal, the saccharin salt of chlordiazepoxide was obtained from a physical mixture of both components by grinding them with a small volume of solvent and by crystallizing them with complete evaporation of the solvent. The resulting salt was examined by methods such as Powder X-ray Diffraction (PXRD), Single Crystal X-ray Diffraction (SCXRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Fourier Transform Infrared (FT-IR), and Raman spectroscopy. The results of the studies proved that saccharin salt of chlordiazepoxide crystallizes in the orthorhombic Pbca space group with one chlordiazepoxide cation and one saccharin anion in the asymmetric unit. In the crystal of the title compound, the chlordiazepoxide cation and the saccharin anion interact through strong N–H···O hydrogen bonds and weak C–H···O hydrogen bonds. The disappearance of the N–H band in the FT-IR spectrum of saccharin may indicate a shift of this proton towards chlordiazepoxide, while the disappearance of the aromatic bond band in the chlordiazepoxide ring in the Raman spectrum may suggest the formation of intermolecular hydrogen bonds between chlordiazepoxide molecules. The melting point of the salts differs from that of the starting compounds. Thermal decomposition of the salt begins above 200 °C and shows at least two overlapping stages of mass loss. In summary, the results of the research showed that the crystalline salt of the saccharin and chlordiazepoxide can be obtained by various methods: grinding with the addition of acetonitrile and crystallization from acetonitrile or a mixture of methanol with methylene chloride.