Effect of milling on DSC thermogram of excipient adipic acid

Quality by design approach for fabrication of extended-release buccal films for xerostomia employing hot-melt extrusion technology

The study endeavors the fabrication of extended-release adipic acid (APA) buccal films employing a quality by design (QbD) approach. The films intended for the treatment of xerostomia were developed utilizing hot-melt extrusion technology. The patient-centered quality target product profile was created, and the critical quality attributes were identified accordingly. Three early-stage formulation development trials, complemented by risk assessment aligned the formulation and process parameters with the product quality standards. Employing a D-optimal mixture design, the formulations were systematically optimized by evaluating three formulation variables: amount of the release-controlling polymer Eudragit® (E RSPO), bioadhesive agent Carbopol® (CBP 971P), and pore forming agent polyethylene glycol (PEG 1500) as independent variables, and % APA release in 1, 4 and 8 h as responses. Using design of experiment software (Design-Expert®), a total of 16 experimental runs were computed and extruded using a Thermofisher ScientificTM twin screw extruder. All films exhibited acceptable content uniformity and extended-release profiles with the potential for releasing APA for at least 8 h. Films containing 30% E RSPO, 10% CBP 971P, and 20% PEG 1500 released 88.6% APA in 8 h. Increasing the CBP concentration enhanced adhesiveness and swelling capacities while decreasing E RSPO concentration yielded films with higher mechanical strength. The release kinetics fitted well into Higuchi and Krosmeyer-Peppas models indicating a Fickian diffusion release mechanism.

A New Family of Renewable Thermosets: Kraft Lignin Poly-adipates

Thermosetting polymeric materials have advantageous properties and are therefore used in numerous applications. In this study, it was hypothesized and ultimately shown that thermosets could be derived from comparably sustainable sub-components. A two-step procedure to produce a thermoset comprising of Kraft lignin (KL) and the cross-linker adipic acid (AdA) was developed. The cross-linking was activated by means of an acetylating agent comprising isopropenyl acetate (IPA) to form a cross-linking mixture (CLM). The cross-linking was confirmed by FTIR and solid-state NMR spectroscopy, and the esterification reactions were further studied using model compounds. When the KL lignin was mixed with the CLM, partial esterification occurred to yield a homogeneous viscous liquid that could easily be poured into a mold, as the first step in the procedure. Without any additions, the mold was heated and the material transformed into a thermoset by reaction of the two carboxylic acid-derivatives of AdA and KL in the second step.

Polymorphic transition due to grinding: the case of 3-[1-(tert-butoxycarbonyl)azetidin-3-yl]-1,2-oxazole-4-carboxylic acid

A polymorphic transition as a result of grinding was found for 3-[1-(tert-butoxycarbonyl)azetidin-3-yl]-1,2-oxazole-4-carboxylic acid. The thorough study of polymorphic structures before and after crystal structure transformation has revealed some pre-conditions for a polymorphic transition and regularities of changes in molecular and crystal structure. In metastable polymorph 1a, the conformationally flexible molecule adopts a conformation with the higher energy and forms a less preferable linear supramolecular synthon. Additional energy imparted to a crystal structure during the grinding process proved to be enough to overcome low energy barriers for the nitrogen inversion and rotation of the oxazole ring around the sp³-sp² single bond. As a result, polymorph 1b with a molecule adopting conformation with lower energy and forming a more preferable centrosymmetric supramolecular synthon was obtained. The study of pairwise interaction energies in the two polymorphs has shown that metastable polymorph 1a is organized by molecular building units and has a columnar-layered structure. A centrosymmetric dimer should be recognized as a complex building unit in more stable polymorph 1b, which has a layered structure.

Co-Crystals of Etravirine by Mechanochemical Activation

The co-crystals formation of etravirine with three carboxylic acids was investigated. New co-crystals of etravirine with adipic acid, benzoic acid, and 4-hydroxybenzoic acid have been synthesized by wet milling of ingredients for 120 min. The novelty of these solid forms was first evidenced by powder X-ray diffraction. Their different morphology was evidenced by SEM microscopy. Spectroscopic analyses (FT-IR, MAS-NMR, and XPS) highlighted the hydrogen bonds between etravirine and co-formers, as a result of the solid-state reaction of the ingredients by wet milling. Thermal analyses pointed out that the milling process caused in co-crystals a reduction in the fusion enthalpy and the melting temperature, compared to the values obtained for etravirine. These co-crystals are stable up to four months on storage under extreme conditions, excepting the co-crystal with benzoic acid which begins to transform into a polymorph of etravirine after 30 days. The UV absorption spectra of the samples tested in three simulated physiological media with pH values of 6, 6.3, and 7 have evidenced the conformation change of etravirine due to hydrogen bonds between etravirine and carboxylic acids.

Characterizing and Exploring the Differences in Dissolution and Stability Between Crystalline Solid Dispersion and Amorphous Solid Dispersion

Solid dispersion is one of the most effective ways to improve the dissolution of insoluble drugs. When the carrier can highly disperse the drug, it will increase the wettability of the drug and reduce the surface tension, thus improving the solubility, dissolution, and bioavailability. However, amorphous solid dispersions usually have low drug loading and poor stability. Therefore, the goal of this work is to study the increased dissolution and high stability of high drug-loading crystalline solid dispersion (CSD), and the difference in dissolution and stability of high-loading and low-loading amorphous solid dispersion (ASD). A CSD of nimodipine with a drug loading of 90% was prepared by wet milling, with hydroxypropyl cellulose (model: HPC-SL) and sodium dodecyl sulfate as stabilizers and spray drying. At the same time, the gradient drug-loaded ASD was prepared by hot melt extrusion with HPC-SL as the carrier. Each preparation was characterized by DSC, PXRD, FT-IR, SEM, and in vitro dissolution testing. The results indicated that the drug in CSD existed in a crystalline state. The amorphous drug molecules in the low drug-loading ASD were uniformly dispersed in the carrier, while the drug state in the high drug-loading ASD was aggregates of the amorphous drug. At the end of the dissolution assay, the 90% drug-loading CSD increased cumulative dissolution to 60%, and the 10% drug-loading ASD achieved a cumulative dissolution rate of 90%.

Preparation and characterization of carnauba wax/adipic acid oleogel: A new reinforced oleogel for application in cake and beef burger

In this study, the reinforced carnauba wax (CW)-based oleogel with adipic acid (AA) was prepared and its potential for application in the cake and the beef burger was evaluated. As a result, the addition of AA in CW-based oleogels caused to form new intramolecular or intermolecular hydrogen bonding, and improve the thermal behavior and crystallinity of oleogels. Additionally, the increase of AA concentration higher than 3% of oleogel formulation significantly increased the strength of oleogels. The formulated food models (cake and beef burger) with partial substitution CW2%/AA4% oleogel as the optimized sample showed an acceptable texture profile, color, and organoleptic characteristics. Consequently, reinforced oleogel with carnauba wax/adipic acid in bakery and meat products can provide considerable promise to develop food products with lower saturated and trans-fatty acid.

An overview of microplastics characterization by thermal analysis

Microplastics may be present in the environment as primary microplastics (manufactured) or secondary microplastics (result of the continuous degradation of larger plastic pieces into smaller fragments due to environmental, physicochemical and biotic factors). To fully understand the dynamics of microplastic particles and their environmental effects, harmonized, automated, cheap, rapid and reliable methodologies for sampling, extraction and characterization of microplastic need to be developed. This review focuses on the potential of thermal analytical techniques for microplastics characterization and highlights some of the new trends in this area.

Comments on "What if Cocrystallization Fails for Neutral Molecules? Screening Offered Eutectics as Alternate Pharmaceutical Materials: Leflunomide-A Case Study"

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Pharmacokinetic Evaluation of 99mTc-radiolabeled Solid Lipid Nanoparticles and Chitosan Coated Solid Lipid Nanoparticles

BACKGROUND

Solid Lipid Nanoparticles (SLNs) possess unique in vivo features such as high resistivity, bioavailability, and habitation at the target site. Coating nanoparticles with polymers such as chitosan greatly affects their pharmacokinetic behavior, stability, tissue uptake, and controlled drug delivery. The aim of this study was to prepare and evaluate the biodistribution of 99mTc-labeled SLNs and chitosan modified SLNs in mice.

METHODS

99mTc-oxine was prepared and utilized to radiolabel pre-papered SLNs or chitosan coated SLNs. After purification of radiolabeled SLNs (99mTc-SLNs) and radiolabeled chitosan-coated SLNs (99mTc-Chi-SLNs) using Amicon filter, they were injected into BALB/c mice to evaluate their biodistribution patterns. In addition, nanoparticles were characterized using Transmission Electron Microscopy (TEM), Fourier-transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-ray Powder Diffraction (XRD) and Dynamic Light Scattering (DLS).

RESULTS

99mTc-oxine with high radiochemical purity (RCP~100%) and stability (RCP > 97% at 24 h) was used to provide 99mTc-SLNs and 99mTc-Chi-SLNs with high initial RCP (100%). TEM image and DLS data suggest 99mTc- SLNs susceptibility to aggregation. To that end, the main portion of 99mTc-SLNs radioactivity accumulates in the liver and intestines, while 99mTc-Chi-SLNs sequesters in the liver, intestines and kidneys. The blood radioactivity of 99mTc-Chi-SLNs was higher than that of 99mTc-SLNs by 7.5, 3.17 and 3.5 folds at 1, 4 and 8 h post-injection. 99mTc- Chi-SLNs uptake in the kidneys in comparison with 99mTc-SLNs was higher by 37.48, 5.84 and 11 folds at 1, 4 and 8h.

CONCLUSION

The chitosan layer on the surface of 99mTc-Chi-SLNs reduces lipophilicity in comparison with 99mTc- SLNs. Therefore, 99mTc-Chi-SLNs are less susceptible to aggregation, which leads to their lower liver uptake and higher kidney uptake and blood concentration.

Identification of Polymorphic Forms of Active Pharmaceutical Ingredient in Low-Concentration Dry Powder Formulations by Synchrotron X-Ray Powder Diffraction

Background

The identification of different (pseudo) polymorphs of an active pharmaceutical ingredient in dry powder formulations is of importance during development and entire product lifecycle, e.g., quality control. Whereas determination of polymorphic differences of pure substances is rather easy, in dry powder formulations, it is generally difficult and the difficulties increase particularly, if the substance of interest is present only in low concentrations in the formulation. Such a formulation is Spiriva^® inhalation powder (Boehringer Ingelheim), which contains only 0.4 w/w% of the active pharmaceutical ingredient tiotropium bromide monohydrate in a matrix of α-lactose monohydrate as excipient.

Methods

In this study, identification of 0.4 w/w% tiotropium bromide in the dry powder formulation was examined by X-ray powder diffraction (XRPD) using a synchrotron radiation source and the results were compared with the conventional laboratory XRPD measurements.

Results

The detection limit of tiotropium bromide by the laboratory XRPD was around 2–5 w/w%, and hence, detection of 0.4 w/w% tiotropium bromide was impossible. The synchrotron XRPD was capable to detect significantly lower level of tiotropium bromide by at least an order of magnitude.

Conclusion

Four different polymorphic forms of tiotropium bromide present at 0.4 w/w% concentration in lactose powder blends were unambiguously identified by the synchrotron XRPD method.

Design and Evaluation of Novel Solid Self-Nanodispersion Delivery System for Andrographolide

Poorly water-soluble drugs offer challenges in developing a formulation product with adequate bioavailability. This study took advantage of the features of nanocrystals and direct compression technologies to develop a novel solid self-nanodispersion delivery system for andrographolide (Andro) in order to increase its dissolution rate for enhancing bioavailability. Andro nanosuspensions (Andro-NS) with a particle size of about 500 nm were prepared by homogenization technology and further converted into dried nanocrystal particles (Andro-NP) via spray-drying. The solid self-nanodispersion delivery system (Andro-SNDS)-loaded Andro-NP was prepared via direct compression technology. The DSC and PXRD results demonstrated that the Andro nanocrystals retained its original crystallinity. The dissolution of the Andro-SNDS formulation was 85.87% in pure water over 30 min, better than those of the coarse Andro and physical mixture of Andro and stabilizer. And the C _max (299.32 ± 78.54 ng/mL) and AUC_0-∞ (4440.55 ± 764.13 mg/L · h) of the Andro-SNDS formulation were significantly higher (p < 0.05) than those of the crude Andro (77.52 ± 31.73 ng/mL and 1437.79 ± 354.25 mg/L · h). The AUC of the Andro-SNDS was 3.09 times as high as that of the crude Andro. This study illustrated a novel approach to combine the features of nanocrystals and composite particles used to improve oral bioavailability of poorly soluble drug.

The role of particle size of glyburide crystals in improving its oral absorption

Currently, nanosizing is becoming increasingly prevalent as an efficient way for the improvement of oral drug absorption. This study mainly focuses on two points, namely the crystal properties, and the in vitro and in vivo characterizations of drug crystals during the nanosizing process. We used glyburide, an oral type 2 diabetes (T2D) medication, as our model drug. We sought to reduce the crystalline size of this drug and evaluate its absorption properties by comparing it with the original coarse drug because of previous reports about its gastrointestinal absorption insufficiency. Glyburide crystals, ranging from 237.6 to 4473 nm were prepared successfully by jet milling and media milling. The particle sizes and the crystal morphology were analyzed by characterization of the solid states, equilibrium solubility, and dissolution behavior. Additionally, pharmacokinetic study was performed in SD rats. The solid state results indicated a loss in crystallinity, amide-imidic acid interconversion, and partial amorphization during nanosizing. Further, in in vitro tests, nanocrystal formulations remarkably increased the solubility and dissolution of the drug (compared to microcrystals). In the in vivo test, reducing the particle size from 601.3 to 312.5 nm showed no improvement on the C _max and AUC _(0-36 h) values, while a profound slowing of the drug elimination occurred with reduction of particle size. Further reduction from 312.5 to 237.6 nm lead to a significant increase (p < 0.001) of the AUC _(0-36 h) from 6857.8 ± 369.3 ng mL^-1 h to 12,928.3 ± 1591.4 ng mL^-1 h, respectively, in rats. Our present study confirmed that nanosizing has a tremendous impact on promoting the oral absorption of glyburide.

Thermo-mechanically responsive crystalline organic cantilever

Dynamic molecular crystals lift weights up to ∼100× heavier than themselves powered by a thermally induced single-crystal to single-crystal phase transition.

Hydroxypropylcellulose as matrix carrier for novel cage-like microparticles prepared by spray-freeze-drying technology

The objective of this study is to design novel dissolution-enhanced microparticles loaded poorly soluble drug nanocrystals used a low viscosity of hydroxypropylcellulose (HPC) as matrix carrier. An interesting approach combined homogenization and the spray-freeze-drying technique was developed. The results demonstrated that the ratio of HPC to drug played an important role in size-reduction efficiency of drug during homogenization. And the formation of cage-like structure of the composite particles depended on ratio of HPC to drug. The spray-freeze-dried composite particles with HPC ratio of 1:2, 1:1 and 2:1 possessed excellent redispersibility, which attributed to its porous matrix and large surface area (3000m²/g). The dissolution of spray-freeze-dried composite particles with higher ratios of HPC (1:2 and 1:1) was significantly enhanced, which attributed to the particle size reduction of drug. The HPC could immobilize drug nanocrystals in its cage-like structure and prevent it from the subsequent agglomeration during storage. In conclusion, the prepared cage-like microparticles is a promising basis for further formulation development.

Comparison of cefpodoxime proxetil release and antimicrobial activity from tablet formulations: complexation with hydroxypropyl-β-cyclodextrin in the presence of water soluble polymer

This study aims to prove the complexation of cefpodoxime proxetil (CP) by hydroxypropyl-β-cyclodextrin (HP-β-CD) in the presence of sodium carboxymethyl cellulose (Na CMC), and makes a comparison of commercial tablets by dissolution and antimicrobial activity studies. The CP--HP-β-CD complex was prepared by kneading method and characterized by SEM, FTIR and DSC. The solubility method was used to investigate the effect of HP-β-CD and Na CMC on the solubility of CP. The complex tablets were prepared using direct compression method. Dissolution studies were performed with complex tablets and commercial tablets in pH 1.2, 4.5, 6.8 and 7.4 buffer solutions. It was observed that complexation occurred in all formulations, and HP-β-CD is able to increase CP solubility and dissolution rate of CP was improved from complex tablets, when compared with commercial tablets. Furthermore, the antimicrobial activity studies revealed that the CP--HP-β-CD complex and complex tablets were shown to have more effective antimicrobial activity than commercial tablets. It is evident from the results that complexation with HP-β-CD in the presence of Na CMC is feasible way to prepare a more efficient tablet formulation with improved dissolution and antimicrobial activity.