Production and characterization of recrystallized linear α-glucans at different temperatures for controllable thermostability and digestibility

Molecular structure of linear α-glucans (LAGs) and crystallization temperature have great effects on the thermostability and digestibility of recrystallized LAGs, but the recrystallization behaviors of LAGs in response to temperature remain unclear. Here LAGs with different lengths were prepared from amylopectin via chain elongation and debranching. Recrystallization of LAGs at 4 °C yielded B-type crystalline structure with relative crystallinity ranged from 23.7% to 46.1%. With a chain length of 40.2, an A-type allomorph was observed for a slow recrystallization at 50 °C. Differential scanning calorimetry suggested that A-type crystal had a higher thermostability than the B-type crystal, and increasing LAGs' chain length improved the dimension of double helices, whose assembly produced starch crystallites that enhanced the thermostability and decreased the in vitro digestibility of recrystallized LAGs. An improved thermostability of recrystallized LAGs preserved their ordered structures and kept the resistance to digestive enzymes, with a RS content up to 75.4%.

Changes in the structure and enzyme binding of starches during in vitro enzymatic hydrolysis using mammalian mucosal enzyme mixtures

Starches are hydrolyzed into monosaccharides by mucosal α-glucosidases in the human small intestine. However, there are few studies assessing the direct digestion of starch by these enzymes. The objective of this study was to investigate the changes in the structure and enzyme binding of starches during in vitro hydrolysis by mammalian mucosal enzymes. Waxy maize (WMS), normal maize (NMS), high-amylose maize (HAMS), waxy potato (WPS), and normal potato (NPS) starches were examined. The order of the digestion rate was different compared with other studies using a mixture of pancreatic α-amylase and amyloglucosidase. NPS was digested more than other starches. WPS was more digestible than WMS. Hydrolyzed starch from NPS, NMS, WPS, WMS, and HAMS after 24 h was 66.4, 64.2, 61.7, 58.7, and 46.2 %, respectively. Notably, a significant change in the morphology, reduced crystallinity, and a decrease in the melting enthalpy of the three starches (NPS, NMS, and WPS) after 24 h of hydrolysis were confirmed by microscopy, X-ray diffraction, and differential scanning calorimetry, respectively. The bound enzyme fraction of NPS, NMS, and WPS increased as hydrolysis progressed. In contrast, HAMS was most resistant to hydrolysis by mucosal α-glucosidases in terms of digestibility, changes in morphology, crystallinity, and thermal properties.

The effect of naringenin-phospholipid complex on thermal oxidative stability of soybean oil under heating condition

Naringenin (NGE), a typical flavanone abundant in citrus fruits, exhibits remarkable antioxidant activities. However, its low solubility in oil restricts its widespread use in inhibiting lipid oxidation. In this study, we present a novel and effective approach to address this limitation by developing a naringenin-phospholipid complex (NGE-PC COM). Comprehensive analytical techniques including Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) were employed to confirm the formation of the NGE-PC COM and elucidate the interaction mechanism between NGE and phospholipids molecules. Notably, the oil-solubility of NGE was significantly enhanced by approximately 2700-fold when formulated as a phospholipid complex in soybean oil. The improved oil-solubility of NGE-PC COM enabled effective inhibition of oil thermal oxidation under high temperature conditions. Generally, this investigation proposed a novel and promising strategy for employing flavanones with strong antioxidant activities to enhance the thermal oxidative stability of edible oil during heating processes.

Thermal characterization and separation of whey proteins by differential scanning calorimetry

Most commercially available whey products contain a mixture of 6-7 whey proteins; however, there is an increased focus on using the individual whey proteins for their unique biological activities. Before extracting individual whey proteins for use, it is important to quantify how much of a particular protein is present in whey mixtures as well as if the protein is still structurally folded. We first characterized the denaturation temperature and enthalpy values for the six purified whey proteins at six pHs (3-9) and under ion chelation using a nano-differential scanning calorimeter (DSC). From the individual protein scans, we determined the optimal condition for detecting all 6 proteins on a single DSC scan was whey in an EDTA MOPs pH 6.7 buffer.

Differential scanning calorimetry in drug-membrane interactions

Differential Scanning Calorimetry (DSC) is a central technique in investigating drug - membrane interactions, a critical component of pharmaceutical research. DSC measures the heat difference between a sample of interest and a reference as a function of temperature or time, contributing essential knowledge on the thermally induced phase changes in lipid membranes and how these changes are affected by incorporating pharmacological substances. The manuscript discusses the use of phospholipid bilayers, which can form structures like unilamellar and multilamellar vesicles, providing a simplified yet representative membrane model to investigate the complex dynamics of how drugs interact with and penetrate cellular barriers. The manuscript consolidates data from various studies, providing a comprehensive understanding of the mechanisms underlying drug - membrane interactions, the determinants that influence these interactions, and the crucial role of DSC in elucidating these components. It further explores the interactions of specific classes of drugs with phospholipid membranes, including non-steroidal anti-inflammatory drugs, anticancer agents, natural products with antioxidant properties, and Alzheimer's disease therapeutics. The manuscript underscores the critical importance of DSC in this field and the need for continued research to improve our understanding of these interactions, acting as a valuable resource for researchers.

Identification and quantification techniques of polymorphic forms - A review

In the pharmaceutical industry, the unexpected appearance of crystalline forms could impact the therapeutic efficacy of an Active Pharmaceutical Ingredient (API). For quality control, a thorough qualitative and quantitative monitoring of pharmaceutical solid forms is essential to ensure the detection and the quantification of crystalline forms, wither different or with the same chemical composition (polymorphs) at a low detection level. The purpose of this paper was to review and highlight the importance of choosing adequate solid-state techniques for detection and quantification APIs that present polymorphism - based on limits of detection (LOD) and quantification (LOQ), pharmacopeias specifications, international guidelines and studies reported in the literature. To this study, the powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), Infrared and Raman spectroscopies and solid-state nuclear magnetic resonance (NMR) were the solid-state techniques analyzed. Additionally, the Argentine, Brazilian, British, European, International, Japanese, Mexican and the United States of America pharmacopeias were reviewed. Based on the analysis performed, the advantages and disadvantages of these techniques, as well as the LOD and LOQ values of APIs were reported. In comparison to these solid-state techniques, reference material used for identification analyses should be previously identified with the corresponding polymorph. Without this previous procedure, the patterns, the spectra, and DSC curves of the reference material can only be used to confirm the mixture of solid forms, not being able to specify which polymorphs are contained in the sample. A major advantage of PXRD is the use of the calculated diffraction patterns obtained from the Crystallographic Information Frameworks (CIFs) files which could be used as a reference pattern without any other information, assistance technique, or physical standards. Regarding the quantification aspect, different pharmacopeias suggest various methods such as the PXRD combining with Rietveld method, which can be used to obtain lower LOD values for minority phases in the mixture of different substances without the need for a calibration curve. Raman spectroscopy can detect polymorphs in small particles and solid-state NMR spectroscopy is a powerful technique for quantification not only crystalline but also crystalline-amorphous mixtures. Finally, this review intends to be a useful tool to control, with efficiency and accuracy, the polymorphism of APIs in pharmaceutical compounds.

A novel Posaconazole oral formulation using spray dried solid dispersion technology: in-vitro and in-vivo study

SD (solid dispersion) technology is one of the well-recognized solubility enhancement methods; but the use of versatile carriers in ASD (amorphous SD) to achieve the added advantage of modified release along with solubility improvement is an emerging area of exploration. Spray drying is a widely used technology with excellent scalability and product attributes. The SD carriers explored were Soluplus®, possessing excellent solubilization properties that may enhance bioavailability and is suitable for innovative processing, and Gelucire 43/01, a lipid polymer utilized in a non-effervescent-based floating gastro-retentive DDS for the modified release of API. The CPPs of spray drying were screened during preliminary trials, and the formulation variables were optimized using a 32 Full Factorial Design. All nine batches were evaluated for % yield, % drug content, flow properties, floating behavior, saturation solubility, and in-vitro drug release in 0.1 N HCl. The optimized batch characterized based on DSC (differential scanning calorimetry) and PXRD (powder X-ray diffraction) confirmed the amorphous nature of entrapped drug in SDD (spray-dried dispersion). Particle size analysis and SEM (scanning electron microscopy) demonstrated micron size irregular shaped particles. Residual solvent analysis by GCMS-HS confirmed the elimination of organic solvents from SDD. The optimized batch was found stable after 6 months stability study as per ICH guidelines. In-vivo roentgenography study in New Zealand white rabbit showed the residence of SDD in gastric environment for sufficient time. The pharmacokinetic study was performed in male Sprague-Dawley rats to determine the bioavailability of developed SDD based product in fasting and fed conditions, and to compare the data with marketed Noxafil formulation. The current research is focused on the development of a novel ternary SDD (spray-dried dispersion)-based gastro-retentive formulation for an anti-fungal drug Posaconazole.

Incorporation of Loratadine-Cyclodextrin Complexes in Oral Thin Films for Rapid Drug Delivery

Rapidly dissolving polymer thin films, or oral thin films (OTFs), have recently emerged as an improved oral drug delivery vehicle with its ability to bypass liver first pass metabolism, longer shelf-life, and simpler transport and distribution requirements, compared to traditional tablets and liquid formulations. Loratadine (LOR), an antihistamine commonly used to treat allergic rhinitis, undergoes liver first pass metabolism and is a prime candidate for incorporation within an OTF. However, loratadine is a BCS II drug with low aqueous solubility. Herein, the solubility of loratadine was improved by complexation with methyl β-cyclodextrin (MBCD) by co-evaporation of 2:1, 1:1, and 1:2 LOR:MBCD ratios and incorporation into a pullulan-based OTF at 4 wt% by solvent casting at 50 °C for 30 - 35 min. A therapeutically relevant 10 mg LOR dose could be prepared in a 3 cm by 3 cm OTF. The feasibility of complexation was observed with a Bs-type phase solubility diagram, and complexation itself was confirmed via differential scanning calorimetry (DSC) by disappearance of the LOR melting peak, Fourier-transform infrared spectroscopy (FTIR) by shifting of the C=O peak, via 1H NMR spectroscopy by downfield shifting and change in peak multiplicity of the LOR aromatic protons, and via diffusion-ordered spectroscopy by a decrease in the diffusion coefficient of LOR:MBCD complex. LOR:MBCD could be incorporated homogeneously throughout an OTF, and LOR:MBCD OTFs exhibited reasonable mechanical strength and endured 12 ± 3 folds before breaking. LOR:MBCD OTFs disintegrated within 38 ± 10 s. The cumulative in vitro release of LOR:MBCD OTFs peaked at 80 % within 3-4 min of dissolution, and LOR in LOR:MBCD OTFs exhibited permeability across a 0.22 μm nitrocellulose membrane, demonstrating its applicability as a rapid drug delivery vehicle.

Stability of Rapidly Crystallizing Sulfonamides Glasses by Fast Scanning Calorimetry: Crystallization Kinetics and Glass-Forming Ability

Production and evaluation of the kinetic stability of the amorphous forms of active pharmaceutical ingredients are among the current challenges of modern pharmaceutical science. In the present work, amorphous forms of several sulfonamides were produced for the first time using Fast Scanning calorimetry. The parameters, characterizing the glass-forming ability of the compounds, i.e. the critical cooling rate of the melt and the kinetic fragility, were determined. The cold crystallization kinetics was studied using both isothermal and non-isothermal approaches. The results of the present study will contribute to the development of approaches for producing amorphous forms of rapidly crystallizing active pharmaceutical ingredients.

Fabrication and In-Vivo Evaluation of Polyvinyl pyrrolidone/Poloxamer 188 Hybrid Nanofibers of Deflazacort

The superior flexibility, efficient drug loading, high surface-to-volume ratio, ease of formulation, and cost-controlled production are considered exceptional advantages of nanofibers (NFs) as a smart delivery system. Deflazacort (DEF) is an anti-inflammatory and immunosuppressant agent. It is categorized as a poorly soluble class II drug. In this study, DEF-loaded polymeric nanofibrous using the electrospinning technique mats, Polyvinyl pyrrolidone (PVP) with or without Poloxamer 188 (PX) were used as mat-forming polymers. Microscopical imaging, drug content (%), and in vitro dissolution studies were conducted for all NFs formulae (F1-F7). All NFs improved the DEF dissolution compared to the unprocessed form, with the superiority of the PVP/PX hybrid. The optimized formula (F7) exhibited an average diameter of 655.46 ± 90.4 nm and % drug content of 84.33 ± 5.58. The dissolution parameters of DEF loaded in PVP/PX NFs (F7) reflected a release of 95.3 % ± 3.1 and 102.6 % ± 1.7 after 5 and 60 min, respectively. NFs (F7) was investigated for drug-polymer compatibility using Fourier-Transform Infrared Spectroscopy (FTIR), Powder X-ray diffraction analysis (PXRD), and Differential Scanning Calorimetry (DSC). In vivo anti-inflammatory study employing male Sprague-Dawley rats showed a significant reduction of rat paw edema for F7 (p < 0.05) compared with unprocessed DEF with a normal epidermal and dermal skin structure comparable to the healthy negative control. Immunohistochemical and morphometric data displayed similarities between the immune reaction of F7 and the negative healthy control. The finding of this work emphasized that DEF loaded in PVP/PX NFs could be considered a useful strategy for enhancing the therapeutic performance of DEF.

PCL/Yam Polysaccharide nanofibrous membranes loaded with self-assembled HP-β-CD/ECG inclusion complexes for food packaging

In this study, Polycaprolactone (PCL)/Yam Polysaccharide (YP) fiber membranes loaded the ultrasound-mediated assembly of 2-Hydroxypropyl-β-cyclodextrin (HP-β-CD)/Epicatechin gallate (ECG) inclusion complexes were prepared by electrospinning technology for food packaging. Morphology, infrared spectroscopy and X-ray diffraction results showed that the inclusion complexes were successfully assembled. With the addition of inclusion complexes, the average diameter of the fibers increased from 2480.96 to 10179.12 nm, the crystallinity decreased, the thermal stability improved, the hydrophilicity enhanced, and the water vapor permeability enhanced. Meanwhile, thermogravimetry and differential scanning calorimetry results showed that the inclusion complexes formed hydrogen bonds between the fibers, which improved the thermal stability, but the mechanical behavior suffered a certain loss. In addition, the fiber membrane could continuously release ECG within 240 h, which showed excellent antibacterial effects both in vitro and in vivo. These results indicated that the fiber film developed based on electrospinning had a broad application prospect in food packaging.

Structure, Self-Assembly, and Phase Behavior of Neuroactive N-Acyl GABAs: Doxorubicin Encapsulation in NPGABA/DPPC Liposomes and Release Studies

N-Acylated amino acids and neurotransmitters in mammals exert significant biological effects on the nervous system, immune responses, and vasculature. N-Acyl derivatives of γ-aminobutyric acid (N-acyl GABA), which belong to both classes mentioned above, are prominent among them. In this work, a homologous series of N-acyl GABAs bearing saturated N-acyl chains (C8-C18) have been synthesized and characterized with respect to self-assembly, thermotropic phase behavior, and supramolecular organization. Differential scanning calorimetric studies revealed that the transition enthalpies and entropies of N-acyl GABAs are linearly dependent on the acyl chain length. The crystal structure of N-tridecanoyl GABA showed that the molecules are packed in bilayers with the acyl chains aligned parallel to the bilayer normal and that the carboxyl groups from opposite layers associate to form dimeric structures involving strong O-H···O hydrogen bonds. In addition, N-H···O and C-H···O hydrogen bonds between amide moieties of adjacent molecules within each layer stabilize the molecular packing. Powder X-ray diffraction studies showed odd-even alternation in the d spacings, suggesting that the odd chain and even chain compounds pack differently. Equimolar mixtures of N-palmitoyl GABA and dipalmitoylphosphatidylcholine (DPPC) were found to form stable unilamellar vesicles with diameters of ∼300-340 nm, which could encapsulate doxorubicin, an anticancer drug, with higher efficiency and better release characteristics than DPPC liposomes at physiologically relevant pH. These liposomes exhibit faster release of doxorubicin at acidic pH (<7.0), indicating their potential utility as drug carriers in cancer chemotherapy.

Influence of Nucleation on Relaxation, Molecular Cooperativity, and Physical Stability of Celecoxib Glass

Although nucleation is considered the first step in the crystallization of glass materials, the structure and properties of the nuclei are not understood well. Influence of nucleation on the structure and dynamics of celecoxib glass was evaluated in this study. The nuclei for Form III were induced by annealing the glass at freezing temperature, and their impact on the relaxation behavior was investigated using thermal analysis and broadband dielectric spectroscopy to find accelerated α relaxation and suppressed β relaxation. In addition, observed after nucleation was a decrease in cooperativity of the molecular motion, presumably because of the appearance of void spaces in the glass structure. During long-term isothermal crystallization studies, crystal growth to Form III was accelerated in the presence of the nuclei, whereas this effect was less remarkable when a different crystal form dominated the crystallization behavior. These observations should provide more detailed insights into the nucleation mechanism and impact of nucleation on molecular dynamics including physical stability of pharmaceutical glasses. In addition, discussed is the remarkable acceleration of the crystallization rate of the celecoxib glass just below its Tg, which could be understood by diffusionless crystal growth.

Differential scanning calorimetry (DSC): An important tool for polymer identification and characterization of plastic marine debris

Differential scanning calorimetry (DSC), a routine thermoanalytical method in material science, is gaining utility in plastic pollution research to improve polymer identification. We optimized a DSC method, experimentally testing pan types, temperature ramps, number of melts, and minimum sample masses. Using the optimized method, we created an in-house thermogram library from 201 polymer reference standards. We determined peak melting temperature cutoffs for differentiating variants of PE and nylon. PE cutoffs remained stable after experimentally weathering standards outdoors or for severely weathered HDPE debris found on Hawaii's beaches. Marine debris samples, across a range of weathering severity and previously identified as either low-density or high-density polyethylene (LDPE or HDPE) based on the 1377 cm-1 peak indicating methyl groups by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), were analyzed by DSC to confirm or challenge the ATR-FTIR PE differentiation. ATR-FTIR was correct for >80% of the HDPE samples, but <40% of those initially identified as LDPE by ATR-FTIR. Accuracy did not relate to weathering extent. Most samples mis-identified as LDPE were HDPE that had formed methyl groups likely from chain scission during photooxidation. ATR-FTIR alone is unreliable for differentiating weathered PE, DSC is required. We provide a multiple-method workflow for complete and accurate polymer identification, even for microplastics ≥0.03 mg. Applying these methods can better identify the polymer composition of marine debris, essential for sourcing and recycling efforts.

Water-mediated phase transformations of posaconazole: An intricate jungle of crystal forms

Posaconazole is a broad-spectrum antifungal agent exhibiting rich polymorphism. Up to now, a total of fourteen different crystal forms have been reported, sometimes with an ambiguous nomenclature, but less is known about their properties and stability relationships. Investigating the solid-state of a drug compound is essential to identify the most stable form under working conditions and to prevent the risk of undesired solid-phase transformations under processing and storage. In this paper, we study posaconazole polymorphism by providing a description of its polymorphs, hydrates, and solvates. Powder X-ray diffraction (PXRD), dynamic vapor sorption (DVS), spectroscopic and thermal techniques were employed to characterize the different forms. In addition, the solid-phase transformations of posaconazole in aqueous suspensions were studied by means of Raman microscopy. Surprisingly, we found that Form S, the crystal form contained in the marketed oral suspension, is not the most stable form in water. Form S readily converts to a more stable hydrate, i.e. Form A, after storage in water for two weeks. In the commercial oral formulation the conversion between the two forms is prevented by the presence of polysorbate 80. Such insights into the stabilizing excipient effects beyond particle dispersion are critical to formulators.

Eutectic Resolves Lysolipid Paradox in Thermoresponsive Liposomes

A better molecular understanding of the temperature-triggered drug release from lysolipid-based thermosensitive liposomes (LTSLs) is needed to overcome the recent setbacks in developing this important drug delivery system. Enhanced drug release was previously rationalized in terms of detergent-like effects of the lysolipid monostearyl lysophosphatidylcholine (MSPC), stabilizing local membrane defects upon LTSL lipid melting. This is highly surprising and here referred to as the 'lysolipid paradox,' because detergents usually induce the opposite effect─they cause leakage upon freezing, not melting. Here, we aim at better answers to (i) why lysolipid does not compromise drug retention upon storage of LTSLs in the gel phase, (ii) how lysolipids can enhance drug release from LTSLs upon lipid melting, and (iii) why LTSLs typically anneal after some time so that not all drug gets released. To this end, we studied the phase transitions of mixtures of dipalmitoylphosphatidylcholine (DPPC) and MSPC by a combination of differential scanning and pressure perturbation calorimetry and identified the phase structures with small- and wide-angle X-ray scattering (SAXS and WAXS). The key result is that LTSLs, which contain the standard amount of 10 mol % MSPC, are at a eutectic point when they release their cargo upon melting at about 41 °C. The eutectic present below 41 °C consists of a MSPC-depleted gel phase as well as small domains of a hydrocarbon chain interdigitated gel phase containing some 30 mol % MSPC. In these interdigitated domains, the lysolipid is stored safely without compromising membrane integrity. At the eutectic temperature, both the MSPC-depleted bilayer and interdigitated MSPC-rich domains melt at once to fluid bilayers, respectively. Intact, fluid membranes tolerate much less MSPC than interdigitated domains─where the latter have melted, the high local MSPC content causes transient pores. These pores allow for fast drug release. However, these pores disappear, and the membrane seals again as the MSPC distributes more evenly over the membrane so that its local concentration decreases below the pore-stabilizing threshold. We provide a pseudobinary phase diagram of the DPPC-MSPC system and structural and volumetric data for the interdigitated phase.

Enhanced dissolution rates of glibenclamide through solid dispersions on microcrystalline cellulose and mannitol, combined with phosphatidylcholine

OBJECTIVE

This study aimed to investigate the impact of physical solid dispersions of spray-dried glibenclamide (SG) on the surface of microcrystalline cellulose (MC) and mannitol (M) surfaces, as well as their combination with phosphatidylcholine (P), on enhancing the dissolution rate of glibenclamide (G).

METHODS

Solid dispersions were prepared using varying proportions of 1:1, 1:4, and 1:10 for SG on the surface of MC (SGA) and M (SGM), and then combined with P, in a proportion of 1:4:0.02 using spray drying. The particle size, specific surface area, scanning electron microscopy (SEM), X-ray diffraction (XRD), and dissolution rate of SGA and SGM were characterized.

RESULTS

SEM analysis revealed successful adhesion of SG onto the surface of the carrier surfaces. XRD showed reduced crystalline characteristic peaks for SGA, while SGM exhibited a sharp peaks pattern. Both SGA and SGM demonstrated higher dissolution rates compared to SG and G alone. Furthermore, the dissolution rates of the solid dispersions of SG, MC and P (SGAP), and SG, M, and P (SGMP) were sequentially higher than that of SGA and SGM.

CONCLUSIONS

The study suggests that physical solid dispersions of SG on MC and M, along with their combination with P, can effectively enhance the dissolution rate of G. These findings may be valuable in developing of oral solid drug dosage forms utilizing SGA, SGM, SGAP, and SGMP.

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.

The inhibition mechanism of bound polyphenols extracted from mung bean coat dietary fiber on porcine pancreatic α-amylase: kinetic, spectroscopic, differential scanning calorimetric and molecular docking

The inhibitory mechanisms of purified bound polyphenols extracted from mung bean coat dietary fiber (pMBDF-BP) on porcine pancreatic α-amylase (PPA) were investigated through inhibition kinetics, fluorescence spectroscopy, circular dichroism, differential scanning calorimetry and molecular docking. It was shown that pMBDF-BP exerted significant reversible inhibition on PPA in a mixed-type inhibition manner (IC50 = 18.57 ± 0.30 μg/mL), and the combination of the three major components exhibited a synergistic inhibitory effect on PPA. Further, pMBDF-BP bound to the active site or form a polyphenol-enzyme complex at the inactive site through hydrogen bonding and hydrophobic forces, via enhancing the hydrophobicity of the microenvironment surrounding tryptophan and tyrosine residues and promoting the secondary structure of PPA towards a more stable conformation, eventually reducing the enzyme activity. This study provided theoretical evidences for the utilization of bound polyphenols extracted from mung bean coat dietary fiber as a functional component in natural inhibitors of α-amylase.

A novel cationic β-cyclodextrin decorated with a choline-like pendant exhibits Iodophor, Mucoadhesive and bactericidal properties

Iodine is a vital microelement and a powerful antiseptic with a rapid and broad spectrum of action. The development of iodophor compounds to improve the solubility and stability of iodine is still challenging. Here, we report the synthesis of a novel cationic β-cyclodextrin bearing a choline-like pendant (β-CD-Chol) designed to complex and deliver iodine to bacterial cells. The characterization of β-CD-Chol and the investigation of the inclusion complex with iodine were performed by NMR spectroscopy, mass spectrometry, UV-vis spectrophotometry, isothermal titration calorimetry, and dynamic light scattering. The functionalization with the positively charged unit conferred improved water-solubility, mucoadhesivity, and iodine complexation efficiency to the β-CD scaffold. The water-soluble β-CD-Chol/iodine complex efficiently formed both in solution and by solid-vapor reaction. The solid complex exhibited a significant stability for months. Iodine release from the inclusion complex was satisfactory and the bactericidal activity was proved against a Staphylococcus epidermidis strain. The absence of cytotoxicity tested on human keratinocytes and the improved mucoadhesivity make β-CD-Chol a promising drug delivery system and an appealing iodophor candidate for iodine-based antisepsis including mucosa disinfection.

Preparation and characterization of new salts of tioconazole. Comparison of their dissolution performance

Tioconazole is an effective antifungal agent with very low solubility in aqueous media, which limits its bioavailability and efficacy. Aiming to overcome the drug limitations by improving the solubility of this active pharmaceutical ingredient, solution precipitation techniques were employed to prepare four new crystalline salts, namely the mesylate, tosylate, maleate (1:1), and fumarate (1:1) hemihydrate. The thermal stabilities, dissolution properties, and structural characteristics of the solids were determined, and the study was extended to compare their properties with the already-known oxalate salt. The structural characterization of the new phases was carried out using a multi-method approach, which included thermal (differential scanning calorimetry and thermogravimetry), diffractometric (powder X-ray diffraction), and spectroscopic (near-infrared and mid-infrared) methodologies. The determination of the melting point of the salts confirmed the findings made by thermal methods. Functional characteristics of the salts, involving their intrinsic dissolution rates were also determined. It was found that the salts exhibited improved thermal stability and that the nature of the counterion modulated their dissolution characteristics. The salts displayed better intrinsic dissolution rates than the free base, to the point of being "highly soluble" according to the Biopharmaceutical Classification System. At pH 4.3, the sulfonic acid derivatives exhibited better dissolution rates than their carboxylic acid-derived counterparts, greatly improved regarding bare tioconazole. The results suggest that the salts have great potential to be used as replacements for the free base; in principle, careful salt selection may help to fulfill each solubility need for the different scenarios where the drug may be used.

Preparation and Characterization of a Rifampicin Coamorphous Material with Tromethamine Coformer: An Experimental-Theoretical Study

Rifampicin (RIF) is an antibiotic used to treat tuberculosis and leprosy. Even though RIF is a market-available drug, it has a low aqueous solubility, hindering its bioavailability. Among the strategies for bioavailability improvement of poorly soluble drugs, coamorphous systems have been revealed as an alternative in the increase of the aqueous solubility of drug systems and at the same time also increasing the amorphous state stability and dissolution rate when compared with the neat drug. In this work, a new coamorphous form from RIF and tromethamine (TRIS) was synthesized by slow evaporation. Structural, electronic, and thermodynamic properties and solvation effects, as well as drug-coformer intermolecular interactions, were studied through density functional theory (DFT) calculations. Powder X-ray diffraction (PXRD) data allowed us to verify the formation of a new coamorphous. In addition, the DFT study indicates a possible intermolecular interaction by hydrogen bonds between the available amino and carbonyl groups of RIF and the hydroxyl and amino groups of TRIS. The theoretical spectra obtained are in good agreement with the experimental data, suggesting the main interactions occurring in the formation of the coamorphous system. PXRD was used to study the physical stability of the coamorphous system under accelerated ICH conditions (40 °C and 75% RH), indicating that the material remained in an amorphous state up to 180 days. The thermogravimetry result of this material showed a good thermal stability up to 153 °C, and differential scanning calorimetry showed that the glass temperature (Tg) was at 70.0 °C. Solubility studies demonstrated an increase in the solubility of RIF by 5.5-fold when compared with its crystalline counterpart. Therefore, this new material presents critical parameters that can be considered in the development of new coamorphous formulations.

Development and optimization of kaempferol loaded ethosomes using Box-Behnken statistical design: In vitro and ex-vivo assessments

Kaempferol (KMP) belong to flavonoid class have developed in ethosomal formulation and were evaluated for their potential to treat diabetic foot ulcers. Even though ethosomes are highly deformable, they can pass through human skin intact. KMP ethosomes were formulated using the cold method and optimized by Box-Behnken design (BBD) (three-factor, three-level (33 )). The formulation variables used for optimization are drug concentration of KMP, soylecithin content, and ethanol percentage. The optimized formulation was examined using transmission electronic microscopy (TEM), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, in-vitro release, ex-vivo permeation studies, and storage stability. The optimized KMP ethosomes was found to have vesicle size (VS) of 283 ± 0.3 nm and zeta potential (ZP) of -29.67 ± 0.3 mV, polydispersity index (PDI) of 0.36, % entrapment efficiency (%EE) of 91.02 ± 0.21%, drug loading (%) of 46.23 ± 2.5% followed by good storage stability at 4°C/60 ± 5% RH. In vitro drug release of optimized KMP ethosomes was 88.2 ± 2.75%, which was approximately double when compared with pure KMP release, that is 49.9 ± 1.89%. The release kinetics for optimized KMP ethosomes follows the Korsmeyer-Peppas model. An apparent permeation coefficient of 356.25 ± 0.5 μg/cm2 was determined and compared with pure KMP (118.46 ± 0.3 μg/cm2 ) for 24 h. According to the study, ethosomes can be a cutting-edge strategy that offers a new delivery method for prolonged and targeted distribution of KMP in a variety of dosage forms including oral, topical, transdermal, and so forth.

Rubusoside As a Multifunctional Stabilizer for Novel Nanocrystal-Based Solid Dispersions with a High Drug Loading: A Case Study

The oral bioavailability of poorly soluble drugs has always been the focus of pharmaceutical researchers. We innovatively combined nanocrystal technology and solid dispersion technology to prepare novel nanocrystalline solid dispersions (NCSDs), which enable both the solidification and redispersion of nanocrystals, offering a promising new pathway for oral delivery of insoluble Chinese medicine ingredients. The rubusoside (Rub) was first used as the multifunctional stabilizer of novel apigenin nanocrystal-based solid dispersions (AP-NSD), improving the in vitro solubilization rate of the insoluble drug apigenin(AP). AP-NSD has been produced using a combination of homogenisation and spray-drying technology. The effects of stabilizer type and concentration on AP nanosuspensions (AP-NS) particles, span, and zeta potential were studied. And the effects of different types of protective agents on the yield and redispersibility of AP-NSD were also studied. Furthermore, AP-NSD was characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD). Solubility was used to assess the in vitro dissolution of AP-NSD relative to APIs and amorphous solid dispersions (AP-ASD), and AP-ASD was prepared by the solvent method. The results showed that 20% Rub stabilized AP-NSD exhibited high drug-loading and good redispersibility and stability, and higher in vitro dissolution rate, which may be related to the presence of Rub on surface of drug. Therefore provides a natural and safe option for the development of formulations for insoluble drugs.

Novel rivaroxaban-loaded microsphere systems with different surface microstructure for enhanced oral bioavailability

This study compares rivaroxaban-loaded polymeric microsphere systems with three types of surface microstructure. Three types of polymeric microspheres loaded with rivaroxaban were fabricated using a spray-drying technique: solvent-evaporated, surface-attached, and solvent-wet microspheres, depending on whether the drug and additives used are soluble in the solvent. The solvent-evaporated and surface-attached microspheres had a rivaroxaban/polyvinylpyrrolidone/sodium lauryl sulfate (SLS) weight ratio of 1/0.25/2.2, and the solvent-wetted microspheres contained rivaroxaban/polyvinyl alcohol/SLS in equal weight ratio (1/0.25/2). The physicochemical properties of the microspheres were evaluated using scanning electron microscopy, powder X-ray diffraction, differential scanning calorimetry, and particle size distribution analysis. The aqueous solubility and dissolution rate of rivaroxaban in the three types of microspheres were compared to those of the drug powder. The solvent-evaporated, surface-attached, and solvent-wetted microspheres were approximately 208, 140, and 172 times as soluble as the drug powder, and the final dissolution rate (120 min) was approximately 5, 2, and 4 times that of the drug powder, respectively. In addition, the oral bioavailability increased by approximately 2, 1.3, and 1.6 times compared to that of the drug powder (area under drug concentration-time curve: 2101.3 ± 314.8, 1325.2 ± 333.3, and 1664.0 ± 102.6 h·ng/mL, respectively). Finally, the solvent-evaporated microspheres showed the greatest improvement (solvent evaporating microspheres > solvent wetted microspheres > surface-attached microspheres ≥ drug powder). Therefore, the solvent-evaporated microspheres may represent a novel oral dosage form that improves the oral bioavailability of rivaroxaban, a poorly soluble drug.

Preparation and formulation of progesterone para-aminobenzoic acid co-crystals with improved dissolution and stability

The crystal structure of a new Progesterone (PROG) co-crystal with para-aminobenzoic acid (PABA) showing enhanced solution properties is reported. PROG-PABA co-crystal was first identified though an in silico coformer screening process using the CSD Co-crystal deign function, then confirmed through a solution evaporation crystallisation experiment. The resulting co-crystal was characterized using single crystal X-ray diffraction, differential scanning calorimetry and Fourier-transform infrared spectroscopy. Liquid assisted grinding was selected as a suitable scale up method compared to spray drying and antisolvent methods due to minimal starting material phases in the final product. Following scale up, aqueous solubility, stability and dissolution measurements were carried out. PROG-PABA showed increased distinct aqueous solubility and dissolution compared to PROG starting material and was shown to be stable at 75 % relative humidity for 3 months. Tablets containing co-crystal were produced then compared to the Utrogestan® soft gel capsule formulation through a dissolution experiment. PROG-PABA tablets showed a substantial increase in dissolution over the course of the experiment with over 30× the amount of PROG dissolved at the 3-hour time point. This co-crystal shows positive implications for developing an improved oral PROG formulation.

Preparation, Characterization, in-vitro and in-vivo Pharmacokinetic Evaluation of Thermostable Dimethyl Fumarate Cocrystals

Dimethyl fumarate (DMF) is an FDA-approved drug for treating relapsing-remitting multiple sclerosis; but it is susceptible to sublimation leading to its loss during processing. Cocrystals can protect against thermal energy via the interaction of DMF with a coformer via weak forces of interaction. With this hypothesis, we have, for the first time, prepared DMF cocrystals using the solvent evaporation method using coformers like citric acid and succinic acid screened by in-silico predictions and hydrogen bonding properties. Analysis using infra-red (IR), powder x-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and sublimation evaluation characterized cocrystals and their thermostability. Comparative analysis of the release profile has been done by dissolution and pharmacokinetic study of DMF and its cocrystals. The cocrystals have improved thermal stability and better pharmacological activities than DMF. In the safety and efficacy evaluation of the formulated cocrystals, they were found to be non-cytotoxic, antioxidant, and inhibiting IL-6 and TNF-α in PBMC induced by lipopolysaccharide (LPS). We have obtained cocrystals of DMF with improved thermal stability and better pharmacological activities than DMF.

Enhancement of the solubility and oral bioavailability of altrenogest through complexation with hydroxypropyl-β-cyclodextrin

Altrenogest (ALT), a synthetic progestogen, serves a critical role in estrus synchronization among animals like gilts and mares. However, its practical application in animal husbandry is hampered due to its poor solubility and limited oral bioavailability. To address this challenge, a solvent evaporation method was employed to create an inclusion complex of ALT with hydroxypropyl-β-cyclodextrin (ALT/HP-β-CD). The formation of this inclusion complex was confirmed by scanning electron microscopy, power X-ray diffraction, differential scanning calorimetry, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and docking calculations. In addition, we further conducted pharmacokinetic investigation involving gilts, comparing ALT/HP-β-CD inclusion complex to an ALT oral solution. The physicochemical characterization results unveiled a transformation of ALT's crystal morphology into an amorphous state, with ALT effectively entering the cavity of HP-β-CD. Compared with ALT, the solubility of ALT/HP-β-CD inclusion complex increased by 1026.51-fold, and its dissolution rate demonstrated significant improvement. Pharmacokinetic assessments further revealed that the oral bioavailability of ALT/HP-β-CD inclusion complex surpassed that of the ALT oral solution, with a relative bioavailability of 114.08 %. In conclusion, complexation with HP-β-CD represents a highly effective approach to improve both the solubility and oral bioavailability of ALT.

DNA-based assay for calorimetric determination of protein concentrations in pure or mixed solutions

It was recently reported that values of the transition heat capacities, as measured by differential scanning calorimetry, for two globular proteins and a short DNA hairpin in NaCl buffer are essentially equivalent, at equal concentrations (mg/mL). To validate the broad applicability of this phenomenon, additional evidence for this equivalence is presented that reveals it does not depend on DNA sequence, buffer salt, or transition temperature (Tm). Based on the equivalence of transition heat capacities, a calorimetric method was devised to determine protein concentrations in pure and complex solutions. The scheme uses direct comparisons between the thermodynamic stability of a short DNA hairpin standard of known concentration, and thermodynamic stability of protein solutions of unknown concentrations. Sequences of two DNA hairpins were designed to confer a near 20°C difference in their Tm values. In all cases, evaluated protein concentrations determined from the DNA standard curves agreed with the UV-Vis concentration for monomeric proteins. For multimeric proteins evaluated concentrations were greater than determined by UV-Vis suggesting the calorimetric approach can also be an indicator of molecular stoichiometry.

Closer look at the calorimetric lower transition in lipid bilayers

The thermal behavior of unilamellar vesicles has been revisited with differential scanning calorimetry to address the issue of whether it is essential to include interactions between neighboring bilayers in theories and simulations of the ripple phase. The issue focuses on the lower, aka pretransition, and the ripple phase that clearly exists between the lower and main transitions in multilamellar vesicles (MLV). We find anomalous thermal behavior in unilamellar vesicles (ULV) beginning at the same temperature as the lower transition in MLVs, but this feature is considerably broadened and somewhat weaker compared to the lower transition in MLVs. We ascribe this to the difficulty of packing a regular ripple pattern on small spheres. In agreement with a few reports of a ripple phase in direct images of single bilayers, we conclude that interactions between neighboring bilayers are not essential for the ripple phase in lipid bilayers.

Formulation and characterization of glipizide solid dosage form with enhanced solubility

Glipizide, a poor water-soluble drug belongs to BCS class II. The proposed work aimed to enhance the solubility of glipizide by preparing solid dispersions, using polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG). Solvent evaporation method was used for the preparation of glipizide solid dispersions. Solid dispersions were prepared in four different drug-to-polymer ratios i.e. 1:1, 1:2, 1:3 and 1:4. Mainly effect of three polymers (PVP K30, PVP K90 and PEG 6000) was evaluated on the solubility and dissolution of glipizide. The in-vitro dissolution of all prepared formulations was performed under pH 6.8 at 37°C using USP type II apparatus. In-vitro dissolution results revealed that the formulations having high concentrations of the polymer showed enhanced solubility. Enhancements in the solubility and rate of dissolution of the drug were noted in solid dispersion formulations compared to the physical blends and pure drug. Solid dispersions containing polyvinyl pyrrolidone exhibited a more favorable pattern of drug release compared to the corresponding solid dispersions with PEG. An increase in the maximum solubility of the drug within the solid dispersion systems was observed in all instances. Two solid dispersion formulations were optimized and formulated into immediate-release tablets, which passed all the pharmacopoeial and non-pharmacopoeial tests. Fourier transformed Infrared (FTIR) spectroscopy X-ray diffraction (XRD) and Differential scanning calorimetry (DSC) were used to indicate drug: polymer interactions in solid state. Analysis of the solid dispersion samples through characterization tests indicated the compatibility between the drug and the polymer.

Molecular interactions of hydrated co-amorphous systems of prilocaine and lidocaine

It is generally accepted that water as a plasticizer can decrease the glass transition temperatures (Tgs) of amorphous drugs and drug excipient systems. However, previous studies suggest that water, as an anti-plasticizer, can increase the Tgs of co-amorphous systems of prilocaine (PRL) and lidocaine (LID). In order to investigate the intermolecular interactions between water and co-amorphous PRL-LID systems, Fourier transform infrared spectroscopy (FTIR) and principal component analysis (PCA) were conducted. Water was found to bind with the carbonyl groups of PRL and LID molecularly evenly in the hydrated co-amorphous PRL-LID systems. Quantum chemical simulations visually confirmed the interactions between water and co-amorphous PRL-LID systems. Furthermore, the physical stability of hydrated co-amorphous PRL-LID systems was improved due to the anti-plasticizing effect of water, compared with the anhydrous samples. The preference of water to interact with the carbonyl groups of PRL and LID as binding sites could be associated with the anti-plasticizing effect of water on the co-amorphous PRL-LID systems.

Sustained release polymer and surfactant based solid dispersion of andrographolide exhibited improved solubility, dissolution, pharmacokinetics, and pharmacological activity

Andrographolide (AD) is a potent natural product with a wide range of pharmacological activities. However, it has low oral bioavailability due to poor solubility and dissolution rate. Solid dispersion (SD) is a promising technique to improve the solubility and dissolution rate of such molecules. In this study, SD formulation of AD was prepared using Kollidon-SR (KSR) and Poloxamer-407 (P-407) as carriers. SD was prepared using the solvent evaporation method and evaluated for the modulation of solubility of AD. The developed SD formulation was characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR). Further, dissolution rate, yield, drug content, stability, flowability, and pharmacokinetic profile of SD were evaluated. The compatibility of SD with the Caco-2 cells and its impact on the P-glycoprotein (P-gp) mediated efflux was also investigated. Furthermore, carrageenan-induced paw edema, and adjuvant-induced arthritic model were used to evaluate the efficacy of SD. The results showed that SD3 (AD + KSR + P-407, 1:6:8) exhibited the highest solubility and dissolution rate, and significantly improved pharmacokinetic profile compared to native AD. SD3 was found to be stable during storage and displayed excellent yield, drug content, and flowability. This formulation was found to be compatible with the Caco-2 cells and retarded the efflux of P-gp substrate. SD3 also demonstrated substantially better efficacy than native AD in terms of paw edema inhibition (carrageenan-induced paw edema, Wistar rats), and overall improvement of disease condition (in terms of paw edema, arthritic score, AST, ALT, cytokines, radiological changes, and histopathology) in arthritic Wistar rats. In conclusion, SD3 exhibited improved solubility, dissolution rate, pharmacokinetic profile, and pharmacological activity than native AD.

Self-Assembly of Unusually Stable Thermotropic Network Phases by Cellobiose-Based Guerbet Glycolipids

Bicontinuous thermotropic liquid crystal (LC) materials, e.g., double gyroid (DG) phases, have garnered significant attention due to the potential utility of their 3D network structures in wide-ranging applications. However, the utility of these materials is significantly constrained by the lack of robust molecular design rules for shape-filling amphiphiles that spontaneously adopt the saddle curvatures required to access these useful supramolecular assemblies. Toward this aim, we synthesized anomerically pure Guerbet-type glycolipids bearing cellobiose head groups and branched alkyl tails and studied their thermotropic LC self-assembly. Using a combination of differential scanning calorimetry, polarized optical microscopy, and small-angle X-ray scattering, our studies demonstrate that Guerbet cellobiosides exhibit a strong propensity to self-assemble into DG morphologies over wide thermotropic phase windows. The stabilities of these assemblies sensitively depend on the branched alkyl tail structure and the anomeric configuration of the glycolipid in a previously unrecognized manner. Complementary molecular simulations furnish detailed insights into the observed self-assembly characteristics, thus unveiling molecular motifs that foster network phase self-assembly that will enable future designs and applications of network LC materials.

Obtaining two polymorphic forms of paracetamol within the phase diagram with PEG 1500

Studies of the interactions between paracetamol, chosen as model active ingredient, and PEG 1500, a pharmaceutical carrier, are conducted in the solid state. Solid dispersions of PEG 1500 and paracetamol were prepared in different mass ratios. Two temperature cycles are then applied and the characterization is carried out by DSC and X-ray powder diffraction. Following this, a phase diagram is established for each cycle. On second heating, the metastable Form II of paracetamol is obtained within the PEG-based matrix. However, on the second heating, for paracetamol contents higher than 65%, Form I or form II is obtained randomly.

Factors Affecting Stability of RNA - Temperature, Length, Concentration, pH, and Buffering Species

RNA is prone to both chemical degradation and/or physical instability. Some of the factors affecting stability of RNA in solution are its length, 3' poly A tail and 5' cap integrity, excipients, buffering species, pH of the solution, nucleases, and divalent cations. In this work, we showed the effect of temperature, messenger RNA (mRNA) length, buffering species, pH of the solution, and the concentration of mRNA on its chemical and physical stability. Our thermodynamic analysis of a 4000 nucleotide-long mRNA measured an activation energy of 31.5 kcal/mol normalized per phosphodiester backbone. We found mRNA length to be negatively correlated to its stability. Buffering species and pH of the solution affected mRNA integrity along with affecting the onset temperature of melting obtained by Differential Scanning Calorimetry (DSC) thermograms. It was also found that increasing the concentration of mRNA in solution increased its stability.

Solid-State Phase Transformation of Monohydrate and Anhydrous Form II of Sitagliptin Phosphate into a Novel Anhydrous Form IV - Solvent-Driven, Temperature-Induced and Stress Testings

The solid form landscape of sitagliptin phosphate was systematically evaluated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray powder diffraction (XRPD), supported by a plethora of auxiliary analytical techniques. The preformulation experiments resulted in the transition of sitagliptin phosphate monohydrate into a new anhydrous form (designated as form IV), obtained after recrystallization from absolute ethanol. The anhydrous form IV remained stable under stressed conditions (1 month at 25 °C/60 %RH and 40 °C/75 %RH). On the other hand, thermal heating (dehydration) of sitagliptin phosphate monohydrate resulted in conversion into another anhydrous form II. Form II was found to be metastable, because after melting, under exposure at 40 °C/75 %RH for 1 month, or when dissolved in absolute ethanol converted to the stable anhydrous form IV of sitagliptin phosphate. A monotropic relationship was found between both studied anhydrous forms. Intrinsic dissolution tests revealed differences in the dissolution rates between the monohydrate and the anhydrous forms of sitagliptin phosphate. This research corrects the record with an accurate chemical composition of the anhydrous form IV of sitagliptin phosphate that was previously regarded as a hemiethanolate. In addition, the crystal structure of anhydrous form II of sitagliptin phosphate has been solved and reported for the first time.

Effect of stoichiometry upon the characteristics of quercetin-arginine cocrystals formulated through solution crystallization

OBJECTIVE

The aim of this study is to demonstrate the effect of stoichiometry upon characteristics of quercetin-arginine (QCT-Arg) cocrystals.

SIGNIFICANCE

Quercetin (QCT) is a most abundant flavonoid in vegetables and fruits and has been widely used as an antioxidant. However, its oral bioavailability remains low due to poor aqueous solubility. We illustrate that QCT-Arg cocrystals formulated through an optimized stoichiometry can be a useful approach for its solubilization.

METHOD

Cocrystals were prepared using solvent evaporation method. Characterizations were performed through microscopic, spectroscopic, and thermal techniques. The stoichiometry was confirmed from the binary phase diagram which was prepared using thermograms derived from differential scanning calorimetric experiments.

RESULT

Cocrystal formation was accompanied by the conversion of isotropic phase into anisotropic one. Thread-like cocrystals were formed, regardless of QCT-Arg stoichiometry and solvent's polarity. Spectral analyses suggested that cocrystal structure was held together by hydrogen bonding between QCT and Arg. We ruled out the existence of eutectic mixture based on the observation of two eutectic points in the binary phase diagram.

CONCLUSION

Morphology of cocrystals remained unaffected by the solvent type, stoichiometry and the presence of surfactant. We noticed that the cocrystals could improve the aqueous solubility of QCT.

Neurofilament Light Protein Rod Domain Exhibits Structural Heterogeneity

Neurofilaments are neuron-specific proteins that belong to the intermediate filament (IFs) protein family, with the neurofilament light chain protein (NFL) being the most abundant. The IFs structure typically includes a central coiled-coil rod domain comprised of coils 1A, 1B, and 2, separated by linker regions. The thermal stability of the IF molecule plays a crucial role in its ability for self-association. In the current study, we investigated the thermal stability of NFL coiled-coil domains by analyzing a set of recombinant domains and their fusions (NFL1B, NFL1A+1B, NFL2, NFL1B+2, and NFLROD) via circular dichroism spectroscopy and differential scanning calorimetry. The thermal stability of coiled-coil domains is evident in a wide range of temperatures, and thermal transition values (Tm) correspond well between isolated coiled-coil domains and full-length NFL. NFL1B has a Tm of 39.4 °C, and its' fusions, NFL1A+1B and NFL1B+2, have a Tm of 41.9 °C and 41.5 °C, respectively. However, in the case of NFL2, thermal denaturation includes at least two thermal transitions at 37.2 °C and 62.7 °C. These data indicate that the continuous α-helical structure of the coil 2 domain has parts with varied thermal stability. Among all the NFL fragments, only NFL2 underwent irreversible heat-induced denaturation. Together, these results unveil the origin of full-length NFL's thermal transitions, and reveal its domains structure and properties.

Supercritical fluid technology as a strategy for nifedipine solid dispersions formulation: In vitro and in vivo evaluation

Supercritical fluid technology (SFT) is an insufficiently investigated approach for the production of solid dispersions, it is environmentally acceptable and has a high potential for application in the pharmaceutical industry. The aim of this work was to formulate and characterize nifedipine solid dispersions (SDs) produced by the SFT and compare the results with ones obtained by the classical solvent based kneading method. The following in vitro tests were conducted: assay and yield, solvent residues, solid state characterization (FTIR, DSC, XRD), flowability, hygroscopicity, solubility, dissolution and stability. Additionally, bioavailability was examined on an animal model (Wistar rats). The formulation selection for in vivo study was performed using the multilevel categoric experimental design and the health risk assessment. Solid state characterization revealed that formulation obtained by the SFT method and higher ratio of polymer (1:5) have had nifedipine in completely amorphous form. Polymer ratio and method of SDs preparation do influence the investigation characteristics. Dissolution rate was fastest in SDs prepared by the SFT and higher polymer ration (1:5). In vivo data of selected SDs prepared by the kneading (ratio 1:1) and the SFT (ratio 1:5) showed alteration in pharmacokinetic profile after i.v. and p.o. application.

DSC, TGA-FTIR and FTIR Assisted by Chemometric Factor Analysis and PXRD in Assessing the Incompatibility of the Antiviral Drug Arbidol Hydrochloride with Pharmaceutical Excipients

Arbidol hydrochloride is an antiviral product widely used in Russia and China for the treatment of, among other diseases, influenza. In recent years, it has turned out to be highly effective against COVID-19. However, there is little knowledge about its physicochemical properties and its behavior in the presence of various pharmaceutical excipients, which could be useful in the development of new preparations by increasing its solubility and bioavailability. For this reason, binary mixtures composed of arbidol hydrochloride and selected pharmaceutical excipients such as chitosan, polyvinylpyrrolione K-30 and magnesium stearate were prepared and subjected to differential scanning calorimetry (DSC), thermogravimetry combined with Fourier transform infrared spectrometry (TGA-FTIR) and Fourier transform infrared spectrometry (FTIR) analyses. In order to obtain clarity in the interpretation of the outcomes, chemometric calculations with factor analysis (FA) were used. Additionally, a powder X-ray diffraction (PXRD) and an intrinsic dissolution rate study were performed for arbidol hydrochloride itself and in the presence of excipients. As a result of the study, it was revealed that arbidol hydrochloride may undergo polymorphic transformations and be incompatible with chitosan and magnesium stearate. However, mixing arbidol hydrochloride with polyvinylpyrrolidone K-30 guarantees the obtaining of durable and safe pharmaceutical preparations.

Microscopic Cracks Modulate Nucleation and Solid-State Crystallization Tendency of Amorphous Celecoxib

Drugs have been classified as fast, moderate, and poor crystallizers based on their inherent solid-state crystallization tendency. Differential scanning calorimetry-based heat-cool-heat protocol serves as a valuable tool to define the solid-state crystallization tendency. This classification helps in the development of strategies for stabilizing amorphous drugs. However, microscopic characteristics of the samples were generally overlooked during these experiments. In the present study, we evaluated the influence of microscopic cracks on the crystallization tendency of a poorly water-soluble model drug, celecoxib. Cracks developed in the temperature range of 0-10 °C during the cooling cycle triggered the subsequent crystallization of the amorphous phase. Nanoindentation study suggested minimal differences in mechanical properties between samples, although the cracked sample showed relatively inhomogeneous mechanical properties. Nuclei nourishment experiments suggested crack-assisted nucleation, which was supported by Raman data that revealed subtle changes in intermolecular interactions between cracked and uncracked samples. Celecoxib has been generally classified as class II, i.e., a drug with moderate crystallization tendency. Interestingly, classification of amorphous celecoxib may change depending on the presence or absence of cracks in the amorphous sample. Hence, subtle events such as microscopic cracks should be given due consideration while defining the solid-state crystallization tendency of drugs.

Influence of water and trehalose on α- and β-relaxation of freeze-dried lysozyme formulations

Molecular mobility in form of alpha and beta relaxations is considered crucial for characterization of amorphous lyophilizates and reflected in the transition temperatures Tgα and Tgβ. Based on an overview of applied methods to study beta relaxations, Dynamic Mechanical analysis was used to measure Tgα and Tgβ in amorphous freeze-dried samples. Lysozyme and trehalose as well as their mixtures in varying ratios were investigated. Three different residual moisture levels, ranging from roughly 0.5-7 % (w/w), were prepared via equilibration of the freeze-dried samples. Known plasticising effects of water on Tgα were confirmed, also via differential scanning calorimetry. In addition and contrary to expectations, an influence of water on the Tgβ also was observed. On the other hand, an increasing amount of trehalose lowered Tgα but increased Tgβ showing that Tgα and Tgβ are not paired. The findings were interpreted with regard to their underlying molecular mechanisms and a correlation with the known influences of water and trehalose on stability. The results provide encouraging hints for future stability studies of freeze-dried protein formulations, which are urgently needed, not least for reasons of sustainability.

Synergistic effect of CaCO3 addition and in-process cold atmospheric plasma treatment on the surface evolution, mechanical properties, and in-vitro degradation behavior of FDM-printed PLA scaffolds

The ease of processing and biocompatibility of polylactic acid (PLA) have made it a widely used material for fused deposition modeling (FDM)-based 3D printing. In spite of this, PLA suffers from some limitations for its extensive use in tissue engineering applications, including poor wettability, low degradation rate, and insufficient mechanical properties. To address the previously mentioned limitations, this study examined how combining in-process cold atmospheric plasma treatment with the inclusion of CaCO3 influences the properties of FDM-printed PLA scaffolds. Differential scanning calorimetry results showed that by incorporating CaCO3 micro-particles into the PLA matrix, heterogeneous nucleation promoted the matrix's crystalline content. Scanning electron microscopy analysis revealed that the surface of the PLA-CaCO3 scaffold exhibited increased roughness and improved interlayer bonding after undergoing plasma treatment. Atomic force microscopy revealed a significant (up to 80-fold) increase in the roughness value of PLA scaffolds after the incorporation of CaCO3 and subsequent cold plasma treatment. Furthermore, X-ray photoelectron spectroscopy analysis indicated that atmospheric plasma treatment substantially increased the presence of oxygen-containing bonds, leading to a significant reduction in the water contact angle, which decreased from 89° to 37°. According to the tensile test, the tensile modulus (634.1 MPa) and ultimate tensile strength (25.4 MPa) of PLA were markedly increased and reached 914.3 and 37.2 MPa, respectively, for the plasma-treated PLA-CaCO3 (PT-PLA-CaCO3). Additionally, the in-vitro degradation test showed that PT-PLA-CaCO3 scaffold exhibited higher degradation rate compared to the PLA-CaCO3 sample. Based on the obtained results, it appears that in-process cold atmospheric plasma treatment could serve as an efficient and straightforward method to enhance the properties of 3D-printed composite parts, particularly for tissue engineering applications.

Improved Dissolution Properties of Co-amorphous Probucol with Atorvastatin Calcium Trihydrate Prepared by Spray-Drying

A co-amorphous model drug was prepared by the spray-drying (SD) of probucol (PC) and atorvastatin calcium trihydrate salt (ATO) as low water solubility and co-former components, respectively. The physicochemical properties of the prepared samples were characterized by powder X-ray diffraction (PXRD) analysis, thermal analysis, Fourier transform infrared spectroscopy (FTIR), and dissolution tests. Stability tests were also conducted under a stress environment of 40 °C and 75% relative humidity. The results of PXRD measurements and thermal analysis suggested that PC and ATO form a co-amorphous system by SD. Thermal analysis also indicated an endothermic peak that followed an exotherm in amorphous PC and a physical mixture (PM) of amorphous PC and ATO; however, no endothermic peak was detected in the co-amorphous system. The dissolution profiles for PC in the co-amorphous sample composed of PC and ATO were improved compared to those for raw PC crystals or the PM. Stability tests indicated that the co-amorphous material formed by PC and ATO can be stored for 35 d without crystallization, whereas amorphous PC became crystallized within a day. Therefore, co-amorphization of PC and ATO prepared by SD is considered to be a useful method to improve the solubility of PC in water.

Effects of different sources of proteins on the formation of starch-lipid-protein complexes

In the present study, the influence of different sources of proteins on the formation of complexes with starch and lipid were investigated. A model system containing wheat starch (WS), palmitic acid (PA) and four proteins (whey protein isolate, egg white protein, soy protein isolate and pea protein isolate) was used to prepare the complexes by Rapid Visco Analyzer. The addition of PA in the pasted WS-protein systems resulted in higher cooling viscosity compared to the pasted WS-PA systems, which was interpreted as being due to the formation of WS-PA-protein complexes. Analyses from differential scanning calorimetry, X-ray diffraction and Raman spectroscopy showed that more complexes were formed in WS-PA-protein systems than in WS-PA systems, especially in the WS-PA-whey protein isolate. The better emulsifying action of whey protein isolate was proposed to be accountable for the greater amounts of complexes formed compared to other three proteins. This study provides important information about the formation of starch-lipid-protein complexes in regard to the selection of proteins for food processing.

Bioderived cellulose fibre-guar gum grafted poly (N, N'-dimethylacrylamide) polymer network for controlled release of metformin hydrochloride

An interpenetrating polymer network (IPN) of areca cellulose and guar gum grafted with poly (N, N'-dimethylacrylamide) was made by microwave irradiation technique. N, N-methylenebisacrylamide (MBA) was used as the crosslinking agent. The network polymer was characterised using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Powder X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). The chemical interaction between the drug and the polymer was studied using Differential Scanning Calorimetry (DSC). The swelling of the gel was measured under different pH conditions and the swelling parameters were evaluated. The gel was loaded with an anti-diabetic drug, Metformin Hydrochloride, and the in vitro drug release was studied in gastric and intestinal conditions. The results indicated complete release of the drug in 6 h under pH 1.2 and in 10 h under pH 7.4. The kinetic analysis of release data indicated the drug release to follow Higuchi's model. The release exponent "n" of Korsmeyer-Peppas model was found to be >0.45 indicating the drug diffusion to be a non-Fickian process.

Influence of Crystal Disorder on the Forced Oxidative Degradation of Vortioxetine HBr

The present study investigates the impact of the solid-state disorder of vortioxetine hydrobromide (HBr) on oxidative degradation under accelerated conditions. A range of solid-state disorders was generated via cryogenic ball milling. The solid-state properties were evaluated by calorimetry, infrared-, and Raman spectroscopies. While salt disproportionation occurred upon milling, no chemical degradation occurred by milling. The amorphous fraction remained physically intact under ambient storage conditions. Subsequently, samples with representative disordered fractions were mixed with a solid oxidative stressor (PVP-H2O2 complex) and were compressed to compacts. The compacts were exposed to 40°C/75% RH for up to 6 h. The sample was periodically withdrawn and analyzed for the physical transformations and degradation. Two oxidative degradation products (DPs) were found to be formed, for which dissimilar relations to the degree of disorder and kinetics of formation were observed. The degradation rate of the major DP formation obtained by fitting the exponential model to the experimental data was found to increase up to a certain degree of disorder and decrease with a further increase in the disordered fraction. In contrast, the minor DP formation kinetics was found to increase monotonically with the increase in the disorder content. For the similar crystallinity level, the degradation trend (rate and extent) differed between the single-phase disorder generated by milling and physically mixed two-phase systems. Overall, the study demonstrates the importance of evaluating the physical and chemical (in)stabilities of the disordered solid state of a salt form of a drug substance, generated through mechano-activation.

Glucans with Different Degrees of Polymerization from Leuconostoc mesenteroides CICC6055: Analysis of Physicochemical Properties and Intestinal Prebiotic Function

This study explored the physicochemical properties and prebiotic activities of glucans and oligoglucans. Oligoglucans were obtained through the fermentation of Leuconostoc mesenteroides CICC6055 and the glucansucrase of strain CICC6055, while glucans were obtained only through fermentation. Thin-layer chromatography and high-performance liquid chromatography identified enzymatically synthesized oligoglucans with a higher yield. Differential scanning calorimetry and derivative thermogravimetry analyses revealed the heat resistance of the glucans and oligoglucans at 280-300 °C. Fourier transform-infrared spectroscopy and nuclear magnetic resonance analyses demonstrated that their main chains were linked with α-1,6-glycosidic bonds accompanied by glucose residue branching. In vitro fermentation experiments demonstrated that they not only improved the contents of short-chain fatty acids but also raised the abundance of predominant flora, such as Bacteroides, Firmicutes, Verrucomicrobia, and Proteobacteria. These results implicate glucansucrase as an efficacious tool for the enzyme synthesis of oligoglucans. Furthermore, both polysaccharides with different degrees of polymerization may be beneficial in maintaining a healthy human gut.

Amorphization of different furosemide polymorphic forms during ball milling: Tracking solid-to-solid phase transformations

Ball milling is used, not only to reduce the particle size of pharmaceutical powders, but also to induce changes in the physical properties of drugs. In this work we prepared three crystal forms of furosemide (forms Ⅰ, Ⅱ, and Ⅲ) and studied their solid phase transformations during ball milling. Powder X-ray diffraction and modulated differential scanning calorimetry were used to characterize the samples after each milling time on their path to amorphization. Our results show that forms Ⅰ and III directly converted into an amorphous phase, while form Ⅱ first undergoes a polymorphic transition to form Ⅰ, and then gradually loses its crystallinity, finally reaching full amorphousness. During ball milling of forms Ⅰ and Ⅱ, the glass transition temperature (Tg) of the amorphous fraction of the milled material remains almost unchanged at 75 °C and 74 °C, respectively (whilst the amorphous content increases). In contrast, the Tg values of the amorphous fraction of milled form III increase with increasing milling times, from 63 °C to 71 °C, indicating an unexpected phenomenon of amorphous-to-amorphous transformation. The amorphous fraction of milled forms I and II samples presented a longer structural relaxation (i.e., lower molecular mobility) than the amorphous fraction of milled form III samples. Moreover, the structural relaxation time remained the same for the increasing amorphous fraction during milling of forms I and II. In contrast, the structural relaxation times were always shorter for the amorphous fraction of form III, but increased with increasing amorphous content during milling, confirming amorphous-to-amorphous transformation.