1D and 2D Coordination Polymers of Calcium with Nonsteroidal Anti-Inflammatory Drugs: Synthesis, Crystal Structures, Hirshfeld Surfaces, Antimicrobial and Antioxidant Activities

Four alkaline earth metal complexes of ketoprofen (Hket) and indomethacin (Hind) were synthesized and characterized: [Ca(ket)2(H2O)2]n (1), [Mg(ket)2(H2O)2] (2), [Ca(ind)2(EtOH)2]n (3), and [Mg(ind)2(EtOH)2] (4). All compounds were studied by elemental analysis (EA), flame atomic absorption spectrometry (FAAS), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Crystal structures of 1 and 3 were determined by single crystal X-ray diffraction technique T=100 K. The structure of 1 is dominated by a one-dimensional coordination polymer, while 3 is formed by a two-dimensional layer stabilized by the calcium zig-zag chains and π⋅⋅⋅π stacking interactions. Crystal packing arrangements were characterized by fingerprint plots (FPs) that were derived from the Hirshfeld surfaces (HSs). The antioxidant and antimicrobial activities of complexes were evaluated against Gram-positive and Gram-negative bacteria as well as yeasts.

Variations in the inner core affect the pharmacokinetics of indomethacin-encapsulated polymeric micelles

Hydrophobic ion pairing (HIP) is a drug encapsulation technology that uses electrostatic interactions between a drug and an additive. However, although polymeric micelles can encapsulate hydrophobic drugs in the core, the encapsulated drug often leaks. Therefore, we designed polymeric micelles with HIP functionalized in a hydrophobic inner core using three diblock copolymers comprising polypeptides with different ratios of polar and hydrophobic amino acids and polyethylene glycol (PEG) to encapsulate indomethacin (IND). The three IND-encapsulated HIP micelles showed different area under the curve (AUC) values as an index of blood retention after intravenous injection in mice. Despite having the same PEG shell, IND-PEG-poly(H/F)n showed a 1.56-fold higher AUC than IND-PEG-poly(D/F)n. PEG interface morphologies were evaluated to determine the differences in pharmacokinetic parameters caused by changes in inner core HIP patterns. The micellarized diblock copolymer was desorbed from IND-PEG-poly(D/F)n due to electrostatic repulsion between IND and the diblock copolymer comprising aspartic acid. Our results suggest that changes in the HIP patterns of the micelle inner core affected the PEG interface morphologies, such as PEG density and diblock copolymer desorption from micelles. These phenomena might lead to changes in the interaction of plasma proteins and drug dispositions.

Small molecules modified mesoporous silica nanoparticles orally deliver indomethacin with synergistic effect

Molecularly functional drug delivery systems possessed huge potentials to realize novel drug administration. To explore small molecules modified drug delivery, a series of small molecules modified mesoporous silica nanoparticles (L-Mal-MSNs, D-Mal-MSNs) were established by grafting small molecules. Poorly water-soluble indomethacin (IMC) was chosen to load into these small molecules modified carriers as well as corresponding control carrier, and further to study characteristics and delivery effects of drug loaded carriers. The results indicated that all these small molecules modified carriers formed hydrogen bonds with drugs and can successfully convert drug crystal phase to amorphous state so as to enhance drug dissolution compared to raw drug. In vivo rat intestinal perfusion demonstrated that IMC loaded L-Mal-MSNs performed the fastest drug absorption while analgesic and anti-inflammatory effects of IMC loaded D-Mal-MSNs turned out to be the best, giving hints that D-malic acid exhibited best synergic functions for IMC. The herein small molecules modified delivery system is an effective solution strategy for the current application of analgesia and anti-inflammatory drugs with outstanding significance.

Indomethacin-omeprazole as therapeutic hybrids? Salt and co-amorphous systems enhancing physicochemical and pharmacological properties

Multidrug therapeutic hybrids constitute a promising proposal to overcome problems associated with traditional formulations containing physical mixtures of drugs, potentially improving pharmacological and pharmaceutical performance. Indomethacin (IND) is a non-selective non-steroidal anti-inflammatory drug (NSAIDs) that acts by inhibiting normal processes of homeostasis, causing a series of side effects, such as gastrointestinal symptoms. Proton pump inhibitors, such as omeprazole (OME), have been used to treat such gastrointestinal tract symptoms. In this work, two new multidrug therapeutic hybrids were prepared (an IND:OME salt and an IND:OME co-amorphous system) by ball mill grinding crystalline IND and OME under different conditions, i.e., liquid assisted grinding (LAG) with ethanol and dry grinding, respectively. The crystalline salt returned to a neutral state co-amorphous system when submitted to ball mill grinding in the absence of solvent (dry grinding), but the reverse process (LAG of the IND:OME co-amorphous system) showed partial decomposition of OME. The IND:OME co-amorphous system showed a higher physical stability than the neat IND and OME amorphous materials (with an amorphous stability longer than 100 days, compared to 4 and 16 h for the neat amorphous drugs, respectively, when stored at dry conditions at room temperature). Furthermore, OME presented a higher chemical stability in solution when dissolved from a salt form than from the pure crystalline form. The dissolution studies showed a dissolution enhancement for IND in both salt (1.8-fold after 8 h of dissolution) and co-amorphous (2.5-fold after 8 h of dissolution) forms. Anti-inflammatory activity using a mice paw oedema model showed an increase of the pharmacological response to IND at a lower dose (∼5mg/kg) for both IND:OME salt (2.8-fold) and IND:OME co-amorphous system (3.2-fold) after 6 h, when compared to the positive control group (IND, administered at 10 mg/kg). Additionally, the anti-inflammatory activity of both salt and co-amorphous form was faster than for the crystalline IND. Finally, an indomethacin-induced gastric ulceration assay in mice resulted in a higher mucosal protection at the same dose (40 mg/kg) for both IND:OME salt and IND:OME co-amorphous system when compared with crystalline OME.

Use of Time-Domain NMR for 1H T1 Relaxation Measurement and Fitting Analysis in Homogeneity Evaluation of Amorphous Solid Dispersion

This study examined the usefulness of 1H T1 relaxation measurements for evaluating the homogeneity of amorphous solid dispersion (ASD). Indomethacin and polyvinylpyrrolidone were used to prepare two kinds of ASDs. One was inhomogeneous ASD (ASDmelt) prepared by a melt-quenching method, and the other was homogeneous ASD (ASDsolvent) prepared by a solvent evaporation method. The T1 relaxation was measured by the time-domain NMR (TD-NMR) technique using a low-field NMR system. Curve-fitting analysis of T1 relaxation plots was conducted using the Akaike information criterion. This fitting analysis revealed that the T1 relaxation of ASDmelt and ASDsolvent was biphasic and monophasic, respectively. ASDmelt and ASDsolvent were inhomogeneous and homogeneous on a nanometer scale, respectively, considering the spin diffusion of 1H nuclei. These T1 results were consistent with the Raman mapping of ASDs. From the fitting analysis of 1H T1 relaxation, we conclude that TD-NMR is a promising technique for evaluating ASD homogeneity.

Analysis of stabilization mechanisms in β-lactoglobulin-based amorphous solid dispersions by experimental and computational approaches

Our previous work shows that β-lactoglobulin-stabilized amorphous solid dispersion (ASD) loaded with 70 % indomethacin remains stable for more than 12 months. The stability is probably due to hydrogen bond networks spread throughout the ASD, facilitated by the indomethacin which has both hydrogen donors and acceptors. To investigate the stabilization mechanisms further, here we tested five other drug molecules, including two without any hydrogen bond donors. A combination of experimental techniques (differential scanning calorimetry, X-ray power diffraction) and molecular dynamics simulations was used to find the maximum drug loadings for ASDs with furosemide, griseofulvin, ibuprofen, ketoconazole and rifaximin. This approach revealed the underlying stabilization factors and the capacity of computer simulations to predict ASD stability. We searched the ASD models for crystalline patterns, and analyzed diffusivity of the drug molecules and hydrogen bond formation. ASDs loaded with rifaximin and ketoconazole remained stable for at least 12 months, even at 90 % drug loading, whereas stable drug loadings for furosemide, griseofulvin and ibuprofen were at a maximum of 70, 50 and 40 %, respectively. Steric confinement and hydrogen bonding to the proteins were the most important stabilization mechanisms at low drug loadings (≤ 40 %). Inter-drug hydrogen bond networks (including those with induced donors), ionic interactions, and a high Tg of the drug molecule were additional factors stabilizing the ASDs at drug loading greater than 40 %.

Effect of Structurally Related Compounds on Desupersaturation Kinetics of Indomethacin

PURPOSE

The pharmaceutical literature contains examples wherein desupersaturation from high concentrations does not proceed to equilibrium concentration of the thermodynamically most stable form but remains above equilibrium. The purpose of the current research was to investigate the effect of structurally related compounds on desupersaturation kinetics as a possible explanation for a higher than equilibrium solubility after crystal growth of γ-indomethacin (γ-IMC).

METHODS

Three structurally related compounds (SRC) - cis-sulindac (c-SUL), trans-sulindac (t-SUL) and indomethacin-related compound-A (IMC-A) -were investigated. Desupersaturation kinetics to the most stable γ-IMC, in the presence of c-SUL, t-SUL or IMC-A, was measured at pH 2.0.

RESULTS

The SRCs c-SUL and t-SUL were effective crystallization inhibitors of IMC, while IMC-A was not a potent crystallization inhibitor of IMC. Among the sulindac isomers, t-SUL was a stronger crystallization inhibitor. The apparent solubility of γ-IMC crystals grown from supersaturated solutions in the presence of SRCs matched the equilibrium solubility of γ-IMC. During crystallization of IMC in the presence of IMC-A, the concentration of IMC-A declined initially but rebounded as supersaturation and crystallization rate of IMC declined, suggesting that IMC-A itself became incorporated in the IMC crystal lattice at higher degrees of IMC supersaturation.

CONCLUSIONS

The results suggest that high apparent solubility after crystallization of IMC reported by several authors is not related to the presence of IMC-A impurity. The greater IMC crystal growth rate inhibition by t-SUL than by c-SUL was consistent with the proposed orientation of SUL molecules adsorbed on the IMC crystal, providing a mechanistic understanding of the inhibition.

Supramolecular nanofiber of indomethacin derivative confers highly cyclooxygenase-2 (COX-2) selectivity and boosts anti-inflammatory efficacy

Herein, we report a facile method for converting carboxylate-containing indomethacin (Idm) into a cyclooxygenase-2 (COX-2) selective inhibitor via the amidation of an unnatural peptide sequence (Nal-Nal-Asp). The resulting indomethacin amides (i.e., Idm-Nal-Nal-Asp) have high selectivity for COX-2, and can self-assemble into a one-component supramolecular hydrogel that acts as a 'self-delivery' system for boosting anti-inflammatory efficacy. Self-assembled Idm-Nal-Nal-Asp hydrogel robustly inhibits COX-2 expression in lipopolysaccharide (LPS)-activated Raw 264.7 macrophages while also exhibits superior anti-inflammatory and antioxidant activities via reactive oxygen species (ROS)-related NF-κB and Nrf2/HO-1 pathways. Moreover, a rabbit model of endotoxin-induced uveitis (EIU) reveals that the Idm-Nal-Nal-Asp hydrogel outperforms clinically used 0.1 wt% diclofenac sodium eye drops in terms of in vivo anti-inflammatory efficacy via topical instillation route. As a rational approach to designing and applying COX-2 selective inhibitors, this work presents a simple method for converting non-selective nonsteriodal anti-inflammatory drugs (NSAIDs) into highly selective COX-2 inhibitors that can self-assemble into supramolecular hydrogel for anti-inflammation applications.

How the Presence of Crystalline Phase Affects Structural Relaxation in Molecular Liquids: The Case of Amorphous Indomethacin

The influence of partial crystallinity on the structural relaxation behavior of low-molecular organic glasses is, contrary to, e.g., polymeric materials, a largely unexplored territory. In the present study, differential scanning calorimetry was used to prepare a series of amorphous indomethacin powders crystallized to various extents. The preparations stemmed from the two distinct particle size fractions: 50-125 µm and 300-500 µm. The structural relaxation data from the cyclic calorimetric measurements were described in terms of the phenomenological Tool-Narayanaswamy-Moynihan model. For the 300-500 µm powder, the crystalline phase forming dominantly on the surface led to a monotonous decrease in the glass transition by ~6 °C in the 0-70% crystallinity range. The activation energy of the relaxation motions and the degree of heterogeneity within the relaxing matrix were not influenced by the increasing crystallinity, while the interconnectivity slightly increased. This behavior was attributed to the release of the quenched-in stresses and to the consequent slight increase in the structural interconnectivity. For the 50-125 µm powder, distinctly different relaxation dynamics were observed. This leads to a conclusion that the crystalline phase grows throughout the bulk glassy matrix along the internal micro-cracks. At higher crystallinity, a sharp increase in Tg, an increase in interconnectivity, and an increase in the variability of structural units engaged in the relaxation motions were observed.

Non-salt based co-amorphous formulation produced by freeze-drying

Amino acids-based co-amorphous system (CAM) has shown to be a promising approach to overcome the dissolution challenge of biopharmaceutics classification system class II drugs. To date, most CAM formulations are based on salt formation at a 1:1 M ratio and are prepared by mechanical activation. However, its use in medicinal products is still limited due to the lack of in-depth understanding of non-ionic based molecular interactions. There are also limited studies on the effect of drug-to-co-former ratio, the development of more scalable, less aggressive, manufacturing processes such as freeze drying and its dissolution benefits. This work aims to investigate the effect of the ratio of tryptophan (a model non-ionic amino acid) to indomethacin (a model drug) on a non-salt-based CAM prepared via freeze-drying with the tert-butyl alcohol-water cosolvent system. The CAM material was systemically characterized at various stages of the freeze-drying process using DSC, UV-Vis, FT-IR, NMR, TGA and XRPD. Dissolution performance and physical stability upon storage were also investigated. Freeze-drying using the cosolvent system has been successfully shown to produce CAMs. The molecular interactions involving H-bonding, H/π and π-π between compounds have been confirmed by FT-IR and NMR. The drug release rate for formulations with a 1.5:1 drug: amino acid molar ratio (or 1:0.42 wt ratio) or below is found to be significantly improved compared to the pure crystalline drug. Furthermore, formulation with a 2.3:1 drug:amino acid molar ratio (or 1:0.25 wt ratio) or below have shown to be physically stable for at least 9 months when stored at dry condition (5% relative humidity, 25 °C) compared to the pure amorphous indomethacin. We have demonstrated the potential of freeze-drying using tert-butyl alcohol-water cosolvent system to produce an optimal non-salt-based class II drug-amino acid CAM.

Mechanisms of Drug Solubility Enhancement Induced by β-Lactoglobulin-Based Amorphous Solid Dispersions

Protein-based amorphous solid dispersions (ASDs) have emerged as a promising approach for enhancing solubility in comparison to crystalline drugs. The dissolution behavior of protein-based amorphous solid dispersions (ASDs) was investigated in various pH media. ASDs of four poorly soluble model drugs with acidic (furosemide and indomethacin), basic (carvedilol), and neutral (celecoxib) properties were prepared by spray drying at 30 wt % drug loading with the protein β-lactoglobulin (BLG). The effect of spray-dried BLG (SD-BLG) solubility and protein binding ability with dissolved drugs in solution were investigated to retrieve the mechanisms governing the improvement of drug solubility from the BLG-based ASDs. Powder dissolution results showed that all ASDs obtained a higher maximum concentration (Cmax) compared to the respective pure crystalline drugs. It was found that the solubility increase of the drugs from the ASDs was to a large extent dependent on the solubility of the pure SD-BLG at the investigated pH values (low solubility at pH near the isoelectric point (pI) of BLG). Furthermore, drug-protein interactions in a solution were observed, in particular at pH values where the drugs were neutral. These drug-protein interactions also resulted, to some extent, in the stabilization of the drug in supersaturation.

Controlled release of a non-steroidal anti-inflammatory drug from a photocurable polymeric calcium phosphate cement

In this research, a photocurable composite based on tetracalcuim phosphate ceramic and, hydroxyethyl methacrylate-modified poly(acrylic-maleic acid) was developed and studied as a potential drug delivery system for bone defects. Different concentrations (5, 10 and 20 wt. %) of a non-steroidal anti-inflammatory drug, Indomethacin, were loaded on to the composite and its release behavior was investigated in phosphate buffered solution during 504 h. The obtained release data were fitted by both power law (Peppas) and Weibull equations. The composites were also characterized after different soaking periods using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and Fourier transforming infrared spectroscopy. The results of XRD and SEM analyses revealed the formation of nanosized needle/flake-like apatite crystals on the composites surfaces; however, better apatite formation was observed for the composites loaded with higher amounts of Indomethacin. The morphological observations and quantitative estimations revealed that the loaded composites were gradually degraded in the phosphate-buffered saline. Moreover, a controlled release of Indomethacin was found from the composites in which a higher drug concentration led to a more drug level as well as sustained release profile. In drug release modeling, better regression coefficient was obtained from the Weibull equation, compared to the power law, meaning that the Weibull equation suggests a better description of the indomethacin release from the composites during the whole period of the test. In conclusion, the photocurable composite with apatite formation ability can be successfully used for the controlled release of indomethacin as an anti-inflammatory drug in bone defects.

Wet granulation of co-amorphous indomethacin systems

The feasibility of co-amorphous systems to be wet granulated together with microcrystalline cellulose (MCC) was investigated. Solid state and molecular interactions were analysed for various co-amorphous drug-amino acid formulations of indomethacin with tryptophan and arginine, respectively, via XRPD, DSC and FTIR. The co-amorphous binary systems were produced by ball-milling for 90 min at different molar ratios followed by wet granulation with MCC and water in a miniaturised scale. Tryptophan containing systems showed crystalline reflections in their XRPD diffractograms and endothermal events in their DSC analyses, and were therefore excluded from upscaling attempts. The systems containing arginine were found to be remain amorphous for at least ten months and were upscaled for production in a high-shear blender under application of two different parameter settings. Under the harsher instrument settings, a composition with a low MCC ratio experienced recrystallisation during wet granulation, while all other compositions could be successfully processed via wet granulation and stayed stable for a storage period of at least twelve weeks, indicating that wet granulation of co-amorphous systems can be feasible.

Development and characterization of crosslinked k-carrageenan/sericin blend with covalent agents or thermal crosslink for indomethacin extended release

Modified release of multiparticulate pharmaceutical forms is a key therapeutic strategy to reduce side effects and toxicity caused by high and repeated doses of immediate-release oral drugs. This research focused on the encapsulation of indomethacin (IND) in the crosslinked k-Car/Ser polymeric matrix by covalent and thermal methods to evaluate drug delivery modulation and properties of the crosslinked blend. Therefore, the entrapment efficiency (EE %), drug loading (DL %) and physicochemical properties of the particles were investigated. The particles presented a spherical shape and a rough surface with a mean diameter of 1.38-2.15 mm (CCA) and 1.56-1.86 mm (thermal crosslink). FTIR investigation indicated the presence of IDM in the particles and X-ray pattern showed the maintenance of crystallinity of IDM. The in vitro release in acidic medium (pH 1.2) and phosphate buffer saline solution (pH 6.8) was 1.23-6.81 % and 81-100 %, respectively. Considering the results, the formulations remained stable after 6 months. The Weibull equation was adequately fitted for all formulations and a diffusion mechanism, swelling and relaxation of chain were observed. IDM-loaded k-carrageenan/sericin/CMC increases cell viability (> 75 % for neutral red and > 81 % for MTT). Finally, all formulations present gastro-resistance, pH response and altered release and have the potential to be used as drug delivery careers.

The Influence of Gastrointestinal Biomolecules on Solid-State Transformations in Pharmaceutical Particulates

Adsorption of gut relevant biomolecules onto particles after oral administration of solid oral dosage forms is expected to form a "gastrointestinal corona", which could influence solution-mediated solid-state transformations on exposure of drug particles to gastrointestinal fluids. Low-frequency Raman (LFR) spectroscopy was used in this study to investigate in situ solid-state phase transformations under biorelevant temperature and pH conditions along with the presence of biomolecules. Melt-quenched amorphous indomethacin was used as a model solid particulate, and its solid-state behavior was evaluated at 37 °C and pH 1.2-6.8 with or without the presence of typical bile salt/phospholipid mixtures emulating fed-state conditions. Overall, a change in the solid-state transformation pathway from amorphous to crystalline drug was observed, where an intermediate ε-form that initially formed at pH 6.8 was suppressed by the addition of endogenous gastrointestinal biomolecules. These solid-state changes were corroborated using time-resolved synchrotron small- and wide-angle X-ray scattering (SAXS/WAXS). Additionally, the bile salt and phospholipid mixture partly prevented the otherwise strong aggregation between drug particles at more acidic conditions (pH ≤ 4.5) and helped to shift the balance against the intrinsic hydrophobicity of indomethacin as well as the plasticization effect brought about by the physiological temperature (i.e., the stickiness arising from the supercooled liquid state at 37 °C). The overall results highlight the importance of evaluating the impact that endogenous biomolecules may have on the solid-state characteristics of drug molecules in dissolution media, where analytical tools such as LFR spectroscopy can serve as an attractive avenue for accessing time-resolved solid-state information on time-scales that are difficult to achieve with other techniques such as X-ray diffraction.

Determination of the Solid Content of Active Pharmaceutical Ingredient Powders in Suspension-Type Pharmaceutical Oral Jelly Using Time-Domain NMR

This study determined the content of solid active pharmaceutical ingredient (API) powders dispersed in suspension-type pharmaceutical oral jellies using a low-field time-domain NMR (TD-NMR). The suspended jellies containing a designated API content were prepared and tested. Acetaminophen (APAP), indomethacin (IMC) and L-valine were used as test APIs. First, this study measured the T2 relaxation rate (the reciprocal of T2 relaxation time) by the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence, and then evaluated whether the API content could be determined by the acquired T2 relaxation rate. The T2 relaxation rate negatively correlated with API content to a certain extent, but their correlation was not sufficient for achieving a precise determination. Subsequently, the solid-echo pulse sequence measurement was adopted for this study. We found that NMR signals corresponding to solid components strongly correlated with API content. Thus, this method achieved a precise determination of API contents in suspended jellies. In addition, this study confirmed the effect of API particle size on the T2 relaxation rate by using an L-valine-containing jelly: the T2 relaxation rate became faster when a smaller API size was incorporated into the suspended jelly, while there was no difference in terms of the NMR signals measured by solid-echo pulse sequence. From these findings, TD-NMR could be a powerful tool for evaluating the API dispersion state in suspended oral jellies.

Indomethacin: The Interplay between Structural Relaxation, Viscous Flow and Crystal Growth

Non-isothermal differential scanning calorimetry (DSC) was used to study the influences of particle size (d_aver) and heating rate (q⁺) on the structural relaxation, crystal growth and decomposition kinetics of amorphous indomethacin. The structural relaxation and decomposition processes exhibited d_aver-independent kinetics, with the q⁺ dependences based on the apparent activation energies of 342 and 106 kJ·mol^-1, respectively. The DSC-measured crystal growth kinetics played a dominant role in the nucleation throughout the total macroscopic amorphous-to-crystalline transformation: the change from the zero-order to the autocatalytic mechanism with increasing q⁺, the significant alteration of kinetics, with the storage below the glass transition temperature, and the accelerated crystallization due to mechanically induced defects. Whereas slow q⁺ led to the formation of the thermodynamically stable γ polymorph, fast q⁺ produced a significant amount of the metastable α polymorph. Mutual correlations between the macroscopic and microscopic crystal growth processes, and between the viscous flow and structural relaxation motions, were discussed based on the values of the corresponding activation energies. Notably, this approach helped us to distinguish between particular crystal growth modes in the case of the powdered indomethacin materials. Ediger's decoupling parameter was used to quantify the relationship between the viscosity and crystal growth. The link between the cooperativity of structural domains, parameters of the Tool-Narayanaswamy-Moynihan relaxation model and microscopic crystal growth was proposed.

A High Energy X-ray Diffraction Study of Amorphous Indomethacin

Amorphous pharmaceuticals often possess a wide range of molecular conformations and bonding arrangements. The x-ray pair distribution function (PDF) method is a powerful technique for the characterization of variations in both intra-molecular and inter-molecular packing arrangements. Here, the x-ray PDF of amorphous Indomethacin is shown to be particularly sensitive to the preferred orientations of the chlorobenzyl ring found in isomers in the crystalline state. In some cases, the chlorobenzyl ring has no preferred torsional angle in the amorphous form, while in others evidence of distinct isomer orientations are observed. Amorphous samples with no preferred torsion angles of the chlorobenzyl ring are found to favor enhanced inter-molecular hydrogen bonding, and this is reflected in the intensity of the first sharp diffraction peak. These significant variations in structure rule out amorphous Indomethacin as a possible standard for x-ray PDF measurements. At high humidity, time resolved PDF's for >40 h reveal water molecules forming hydrogen bonds with Indomethacin molecules. A simple linear hydrogen bond model indicates that water molecules in the wet amorphous form have similar hydrogen bond strengths to those found between Indomethacin dimers or chains in the dry amorphous form.

Electron beam induced degradation of indomethacin in aqueous solution: kinetics, degradation mechanism, and toxicity assessment

Pharmaceutical compounds were emerging contaminants, and the accumulation of pharmaceutical compounds in the environment increased the risk to humans and ecosystems. In this study, electron beam irradiation was applied to degrade indomethacin (IDM) in aqueous solution. IDM degradation followed pseudo-first-order kinetics and 300 μM IDM could be completely degraded at only 2 kGy. According to the quenching experiment, the dose constant ratios of oxidative radicals (•OH) and reductive radicals (e^-aq and •H) could be calculated as k_•OH: k_{e aq and •H}=4.79:1. As the concentration of H₂O₂ increased from 0 to 10 mM, the dose constant increased from 1.883 to 2.582 kGy^-1. However, degradation effect would be restrained in the existence of NO^-₃, NO^-₂, CO^2-₃, HCO^-₃, SO^2-, and humic acid due to their competition for the active species. Theoretical calculation revealed the radical attacking sites of IDM molecule and the most probable pathways were proposed with identification of intermediates. The attack of •OH mainly resulted in the cleavage of amide bond, indole ring opening, demethoxylation, and •OH addition. Dechlorination and the reduction of the carbonyl group occurred on IDM molecular through the reduction of e^-_aq and •H. The intermediates could continue to be degraded to small molecule acid, such as formic acid, acetic acid, and oxalic acid. Furthermore, highly toxic IDM transformed into less toxic products during the irradiation process.

Drug Design, Synthesis and Biological Evaluation of Heterocyclic Molecules as Anti-Inflammatory Agents

Non-steroidal anti-inflammatory drugs (NSAIDs) are generally utilized for numerous inflammatory ailments. The long-term utilization of NSAIDs prompts adverse reactions such as gastrointestinal ulceration, renal dysfunction and hepatotoxicity; however, selective COX-2 inhibitors prevent these adverse events. Various scientific approaches have been employed to identify safer COX-2 inhibitors, as in any case, a large portion of particular COX-2 inhibitors have been retracted from the market because of severe cardiovascular events. This study aimed to develop and synthesize a novel series of indomethacin analogues with potential anti-inflammatory properties and fewer side effects, wherein carboxylic acid moiety was substituted using DCC/DMAP coupling. This study incorporates the docking of various indomethacin analogues to detect the binding interactions with COX-2 protein (PDB ID: 3NT1). MD simulation was performed to measure the stability and flexibility of ligand–protein interactions at the atomic level, for which the top-scoring ligand–protein complex was selected. These compounds were evaluated in vitro for COX enzymes inhibition. Likewise, selected compounds were screened in vivo for anti-inflammatory potential using the carrageenan-induced rat paw oedema method and their ulcerogenic potential. The acute toxicity of compounds was also predicted using in silico tools. Most of the compounds exhibited the potent inhibition of both COX enzymes; however, 3e and 3c showed the most potent COX-2 inhibition having IC50 0.34 µM and 1.39 µM, respectively. These compounds also demonstrated potent anti-inflammatory potential without ulcerogenic liability. The biological evaluation revealed that the compound substituted with 4-nitrophenyl was most active.

Indomethacin and Diclofenac Hybrids with Oleanolic Acid Oximes Modulate Key Signaling Pathways in Pancreatic Cancer Cells

Our earlier studies showed that coupling nonsteroidal anti-inflammatory drugs (NSAIDs) with oleanolic acid derivatives increased their anti-inflammatory activity in human hepatoma cells. The aim of this study was to evaluate their effect on the signaling pathways involved in inflammation processes in human pancreatic cancer (PC) cells. Cultured PSN-1 cells were exposed for 24 h (30 µM) to OA oxime (OAO) derivatives substituted with benzyl or morpholide groups and their conjugates with indomethacin (IND) or diclofenac (DCL). The activation of NF-κB and Nrf2 was assessed by the evaluation of the translocation of their active forms into the nucleus and their binding to specific DNA sequences via the ELISA assay. The expression of NF-κB and Nrf2 target genes was evaluated by R-T PCR and Western blot analysis. The conjugation of IND or DCL with OAO derivatives increased cytotoxicity and their effect on the tested signaling pathways. The most effective compound was the DCL hybrid with OAO morpholide (4d). This compound significantly reduced the activation and expression of NF-κB and enhanced the activation and expression of Nrf2. Increased expression of Nrf2 target genes led to reduced ROS production. Moreover, MAPKs and the related pathways were also affected. Therefore, conjugate 4d deserves more comprehensive studies as a potential PC therapeutic agent.

Microemulsions and nanoemulsions modified with cationic surfactants for improving the solubility and therapeutic efficacy of loaded drug indomethacin

In this work, a noncovalent strategy was successfully used to modify colloidal stability andin vitroandin vivoefficacy of two amphiphilic formulations of the anti-inflammatory drug indomethacin. Namely, nanoemulsions and microemulsions based on oleic acid and nonionic surfactants have been produced and compared. The influence of cationic surfactants cetyltrimethylammonium bromide and its carbamate bearing analogue on the size characteristics, stability and ability to provide prolonged action of loaded drug indomethacin has been evaluated. Adding the positively charged molecules in the surface layer of nanoemulsions and microemulsions has shown the stability increase along with maintaining the size characteristics and homogeneity in time. Moreover, the carbamate modified analogue demonstrated beneficial behavior. Indomethacin loaded in microemulsions and nanoemulsions showed prolonged-release (10%-15% release for 5 h) compared to a free drug (complete release for 5 h). The rate of release of indomethacin from nanoemulsions was slightly higher than from microemulsions and insignificantly decreased with an increase in the concentration of the cationic surfactant. For carbamate surfactant nanocarrier loaded with fluorescence probe Nile Red, the ability to penetrate into the cell was supported by flow cytometry study and visualized by fluorescence microscopy.In vitrotests on anti-inflammatory activity of the systems demonstrated that the blood cell membrane stabilization increased in the case of modified microemulsion. The anti-inflammatory activity of the encapsulated drug was tested in rats using a carrageenan-induced edema model. Nanoemulsions without cationic surfactants appeared more efficient compared to microemulsions. Indomethacin emulsion formulations with carbamate surfactant added showed slower carrageenan-induced edema progression compared to unmodified compositions. Meanwhile, the edema completely disappeared upon treatment with emulsion loaded indomethacin after 4 h in the case of microemulsions versus 5 h in the case of nanoemulsions.

Preparation and Characterization of Indomethacin Supramolecular Systems with β-Cyclodextrin in Order to Estimate Photostability Improvement

Cyclodextrins have found wide application in contemporary chemistry, pharmacy and medicine. Because of their unique properties, cyclodextrins are constantly used in research on solubility or stability improvement, as well as other physicochemical properties of medicinal substances. Indomethacin (IND) is a photolabile molecule that also attracts the interest of researchers due to its therapeutic potential and the need to overcome its problematic photosensitivity. Supramolecular complexes of indomethacin with β-cyclodextrin (CD) are already known, and they show greater stability compared to complexes with other types of cyclodextrins. So far, however, the sensitivity to light of physical mixtures and inclusion complexes in the solid phase has not been studied, and their various stoichiometries have not yet been investigated. Due to this fact, the aim of the present study is to obtain supramolecular systems (inclusion complexes and physical mixtures) of indomethacin with three different amounts of β-cyclodextrin. Assessment of the photochemical stability of indomethacin-β-cyclodextrin systems in the solid state is performed in order to find the best correlation between IND stability and the amount of CD. Comparative analysis of physicochemical degradation for stoichiometry systems [CD:IND] = [1:1], [0.5:1] and [0.1:1] is performed by using ultraviolet spectroscopy, transmission—FTIR, reflection—ATR-FTIR infrared spectroscopy and DSC calorimetry.

Enhancing the tumor cell selectivity of a rhodamine-decorated iridium(III) complex by conjugating with indomethacin for COX-2 targeted photodynamic therapy

A rhodamine-iridium (III) complex bearing indomethacin moiety, named IM-rho-Ir, was synthesized and evaluated for COX-2 targetable photodynamic therapy. By integrating COX-2 directing group, IM-rho-Ir exhibited enhanced cellular uptake in cancer cells than in normal cells compared to rhodamine-iridium (III) complex without indomethacin moiety.

Design, Synthesis, In Silico and In Vitro Studies for New Nitric Oxide-Releasing Indomethacin Derivatives with 1,3,4-oxadiazole-2-thiol Scaffold

Starting from indomethacin (IND), one of the most prescribed non-steroidal anti-inflammatory drugs (NSAIDs), new nitric oxide-releasing indomethacin derivatives with 1,3,4-oxadiazole-2-thiol scaffold (NO-IND-OXDs, 8a-p) have been developed as a safer and more efficient multitarget therapeutic strategy. The successful synthesis of designed compounds (intermediaries and finals) was proved by complete spectroscopic analyses. In order to study the in silico interaction of NO-IND-OXDs with cyclooxygenase isoenzymes, a molecular docking study, using AutoDock 4.2.6 software, was performed. Moreover, their biological characterization, based on in vitro assays, in terms of thermal denaturation of serum proteins, antioxidant effects and the NO releasing capacity, was also performed. Based on docking results, 8k, 8l and 8m proved to be the best interaction for the COX-2 (cyclooxygense-2) target site, with an improved docking score compared with celecoxib. Referring to the thermal denaturation of serum proteins and antioxidant effects, all the tested compounds were more active than IND and aspirin, used as references. In addition, the compounds 8c, 8h, 8i, 8m, 8n and 8o showed increased capacity to release NO, which means they are safer in terms of gastrointestinal side effects.

Computational Insights on the Potential of Some NSAIDs for Treating COVID-19: Priority Set and Lead Optimization

The discovery of drugs capable of inhibiting SARS-CoV-2 is a priority for human beings due to the severity of the global health pandemic caused by COVID-19. To this end, repurposing of FDA-approved drugs such as NSAIDs against COVID-19 can provide therapeutic alternatives that could be utilized as an effective safe treatment for COVID-19. The anti-inflammatory activity of NSAIDs is also advantageous in the treatment of COVID-19, as it was found that SARS-CoV-2 is responsible for provoking inflammatory cytokine storms resulting in lung damage. In this study, 40 FDA-approved NSAIDs were evaluated through molecular docking against the main protease of SARS-CoV-2. Among the tested compounds, sulfinpyrazone 2, indomethacin 3, and auranofin 4 were proposed as potential antagonists of COVID-19 main protease. Molecular dynamics simulations were also carried out for the most promising members of the screened NSAID candidates (2, 3, and 4) to unravel the dynamic properties of NSAIDs at the target receptor. The conducted quantum mechanical study revealed that the hybrid functional B3PW91 provides a good description of the spatial parameters of auranofin 4. Interestingly, a promising structure-activity relationship (SAR) was concluded from our study that could help in the future design of potential SARS-CoV-2 main protease inhibitors with expected anti-inflammatory effects as well. NSAIDs may be used by medicinal chemists as lead compounds for the development of potent SARS-CoV-2 (Mpro) inhibitors. In addition, some NSAIDs can be selectively designated for treatment of inflammation resulting from COVID-19.

Crystallography, Molecular Modeling, and COX-2 Inhibition Studies on Indolizine Derivatives

The cyclooxygenase-2 (COX-2) enzyme is an important target for drug discovery and development of novel anti-inflammatory agents. Selective COX-2 inhibitors have the advantage of reduced side-effects, which result from COX-1 inhibition that is usually observed with nonselective COX inhibitors. In this study, the design and synthesis of a new series of 7-methoxy indolizines as bioisostere indomethacin analogues (5a-e) were carried out and evaluated for COX-2 enzyme inhibition. All the compounds showed activity in micromolar ranges, and the compound diethyl 3-(4-cyanobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5a) emerged as a promising COX-2 inhibitor with an IC₅₀ of 5.84 µM, as compared to indomethacin (IC₅₀ = 6.84 µM). The molecular modeling study of indolizines indicated that hydrophobic interactions were the major contribution to COX-2 inhibition. The title compound diethyl 3-(4-bromobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5c) was subjected for single-crystal X-ray studies, Hirshfeld surface analysis, and energy framework calculations. The X-ray diffraction analysis showed that the molecule (5c) crystallizes in the monoclinic crystal system with space group P 2₁/n with a = 12.0497(6)Å, b = 17.8324(10)Å, c = 19.6052(11)Å, α = 90.000°, β = 100.372(1)°, γ = 90.000°, and V = 4143.8(4)ų. In addition, with the help of Crystal Explorer software program using the B3LYP/6-31G(d, p) basis set, the theoretical calculation of the interaction and graphical representation of energy value was measured in the form of the energy framework in terms of coulombic, dispersion, and total energy.

Detection, transformation, and toxicity of indole-derivative nonsteroidal anti-inflammatory drugs during chlorine disinfection

As important emerging contaminants, nonsteroidal anti-inflammatory drugs (NSAIDs) are the most intensively prescribed pharmaceuticals introduced to drinking water due to their incomplete removal in wastewater treatment. While concentrations of NSAIDs in drinking water are generally low, they have been attracting increasing concern as a result of their disinfection byproducts (DBPs) generated in drinking water disinfection. In this work, detection methods were set up for four representative indole-derivative NSAIDs (indomethacin, acemetacin, sulindac, and etodolac) using ultra performance liquid chromatography/electrospray ionization-triple quadruple mass spectrometry (UPLC/ESI-tqMS). ESI+ was better for detection of indomethacin and sulindac, whereas ESI- was suitable to detection of acemetacin and etodolac. With optimized MS parameters, the instrument detection and quantitation limits of the four indole derivatives were achieved to be 1.1-24.6 ng/L and 3.7-41.0 ng/L, respectively. During chlorination, indomethacin and acemetacin could undergo five major reaction types (chlorine substitution, hydrolysis, decarboxylation, C-C coupling, and C-N cleavage) to form a series of DBPs, among which 19 were proposed/identified with structures. Based on the revealed structures of DBPs, transformation pathways of indomethacin and acemetacin in chlorination were partially elucidated. Notably, individual and mixture toxicity of indomethacin and acemetacin before/after chlorination were evaluated using a well-established acute toxicity assessment and a Hep G2 cell cytotoxicity assay, respectively. Results showed that the predicted acute toxicity of a few chlorination DBPs were higher than their precursors; chlorination substantially enhanced the mixture cytotoxicity of indomethacin by over 10 times and slightly increased the mixture cytotoxicity of acemetacin.

Synthesis, structural determination, in vitro and in silico biological evaluation of divalent or trivalent cobalt complexes with indomethacin

The interaction of cobalt chloride with the non-steroidal anti-inflammatory drug indomethacin (Hindo) led to the formation of the polymeric complex [Co(indo-O)2(H2O)2(μ-Cl)]n·n(MeOH·H2O) bearing one chlorido bridge between the cobalt atoms. The presence of the nitrogen-donor co-ligands 2,2'-bipyridine (bipy), 2,2'-bipyridylamine (bipyam), 1,10-phenanthroline (phen) or 1H-imidazole (Himi) resulted in the isolation of complexes [Co2(μ-indo-O,O')2(indo-O)2(bipy)2(μ-H2O)]·3.3MeOH, [Co(indo-O,O')2(bipyam)]·0.9MeOH·0.2H2O, [Co(indo-O,O')2(phen)] (4) and [Co(indo-O)2(Himi)2] (5), respectively, where the indomethacin ligands were coordinated in diverse manners. The study of the affinity of the complexes for calf-thymus DNA revealed their intercalation between the DNA-bases. The binding of the complexes to albumins was also examined and the corresponding binding constants and binding subdomain were determined. The free radical scavenging activity of the compounds was evaluated towards 1,1-diphenyl-picrylhydrazyl and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid). Molecular modeling calculations may usually provide a molecular basis for the understanding of both the impairment of DNA by its binding with the studied complexes and the ability of these compounds to transportation through serum albumin proteins. This study can provide information for the elucidation of the mechanism of action of the compounds in a molecular level.

Virtual Coformer Screening by Crystal Structure Predictions: Crucial Role of Crystallinity in Pharmaceutical Cocrystallization

One of the most popular strategies of the optimization of drug properties in the pharmaceutical industry appears to be a solid form changing into a cocrystalline form. A number of virtual screening approaches have been previously developed to allow a selection of the most promising cocrystal formers (coformers) for an experimental follow-up. A significant drawback of those methods is related to the lack of accounting for the crystallinity contribution to cocrystal formation. To address this issue, we propose in this study two virtual coformer screening approaches based on a modern cloud-computing crystal structure prediction (CSP) technology at a dispersion-corrected density functional theory (DFT-D) level. The CSP-based methods were for the first time validated on challenging cases of indomethacin and paracetamol cocrystallization, for which the previously developed approaches provided poor predictions. The calculations demonstrated a dramatic improvement of the virtual coformer screening performance relative to the other methods. It is demonstrated that the crystallinity contribution to the formation of paracetamol and indomethacin cocrystals is a dominant one and, therefore, should not be ignored in the virtual screening calculations. Our results encourage a broad utilization of the proposed CSP-based technology in the pharmaceutical industry as the only virtual coformer screening method that directly accounts for the crystallinity contribution.

In Situ Gelling Systems Using Pluronic F127 Enhance Corneal Permeability of Indomethacin Nanocrystals

We previously designed an ophthalmic dispersion containing indomethacin nanocrystals (IMC-NCs), showing that multiple energy-dependent endocytoses led to the enhanced absorption of drugs from ocular dosage forms. In this study, we attempted to prepare Pluronic F-127 (PLF-127)-based in situ gel (ISG) incorporating IMC-NCs, and we investigated whether the instillation of the newly developed ISG incorporating IMC-NCs prolonged the precorneal resident time of the drug and improved ocular bioavailability. The IMC-NC-incorporating ISG was prepared using the bead-mill method and PLF-127, which yielded a mean particle size of 50–150 nm. The viscosity of the IMC-NC-incorporating ISG was higher at 37 °C than at 10 °C, and the diffusion and release of IMC-NCs in the IMC-NC-incorporating ISG were decreased by PLF-127 at 37 °C. In experiments using rabbits, the retention time of IMC levels in the lacrimal fluid was enhanced with PLF-127 in the IMC-NC-incorporating ISG, whereby the IMC-NC-incorporating ISG with 5% and 10% PLF-127 increased the transcorneal penetration of the IMCs. In contrast to the results with optimal PLF-127 (5% and 10%), excessive PLF-127 (15%) decreased the uptake of IMC-NCs after instillation. In conclusion, we found that IMC-NC-incorporating ISG with an optimal amount of PLF-127 (5–10%) resulted in higher IMC corneal permeation after instillation than that with excessive PLF-127, probably because of the balance between higher residence time and faster diffusion of IMC-NCs on the ocular surface. These findings provide significant information for developing ophthalmic nanomedicines.

Indomethacin Increases Quercetin Affinity for Human Serum Albumin: A Combined Experimental and Computational Study and Its Broader Implications

Human serum albumin (HSA) is the most abundant carrier protein in the human body. Competition for the same binding site between different ligands can lead to an increased active concentration or a faster elimination of one or both ligands. Indomethacin and quercetin both bind to the binding site located in the IIA subdomain. To determine the nature of the HSA-indomethacin-quercetin interactions, spectrofluorometric, docking, molecular dynamics studies, and quantum chemical calculations were performed. The results show that the indomethacin and quercetin binding sites do not overlap. Moreover, the presence of quercetin does not influence the binding constant and position of indomethacin in the pocket. However, binding of quercetin is much more favorable in the presence of indomethacin, with its position and interactions with HSA significantly changed. These results provide a new insight into drug-drug interactions, which can be important in situations when displacement from HSA or other proteins is undesirable or even desirable. This principle could also be used to deliberately prolong or shorten the xenobiotics' half-life in the body, depending on the desired outcomes.

Significant role of high-valent iron-oxo species in the degradation and detoxification of indomethacine

A novel high-valent iron-oxo species (Fe(IV) = O) generated from Iron hexadecachlorophthalocyanine (FePcCl₁₆)-mediated peroxymonosulfate (PMS) activation under visible light illumination for the degradation of a special group of compounds, indomethacine (IDM), containing methoxy, carboxyl, chloro, and amide groups was investigated. The experimental results indicate that Fe(IV) = O was able to selectively attack the carbonyl C-N bond on twisted amide groups, which exerts a strong toxic effect, and could therefore, effectively degrade and detoxify IDM and its byproducts. Twelve byproducts were identified by HPLC/MS/MS and calculation of frontier electron densities (FEDs), with all amide-group breakage products detected, and the possible pathways were deduced, which mainly consisted of Fe(IV) = O-induced cleavage of amide groups and radicals-induced reactions. Ecological risk assessment further confirmed a decrease in toxicity towards IDM degradation, which provides a promising Fe(IV) = O species for selective oxidation and detoxification of destabilized ground-state amides in drinking-water and wastewater treatment.

The design and development of high drug loading amorphous solid dispersion for hot-melt extrusion platform

Amorphous solid dispersion (ASD) is a formulation strategy extensively used to enhance the bioavailability of poorly water soluble drugs. Despite this, they are limited by various factors such as limited drug loading, poor stability, drug-excipient miscibility and the choice of process platforms. In this work, we have developed a strategy for the manufacture of high drug loaded ASD (HDASD) using hot-melt extrusion (HME) based platform. Three drug-polymer combinations, indomethacin-Eudragit®E, naproxen-Eudragit®E and ibuprofen-Eudragit®E, were used as the model systems. The design spaces were predicted through Flory-Huggins based theory, and the selected HDASDs at pre-defined conditions were manufactured using HME and quench-cooled melt methods. These HDASD systems were also extensively characterised via small angle/wide angle x-ray scattering, differential scanning calorimetry, Infrared and Raman spectroscopy and atomic force microscopy. It was verified that HDASDs were successfully produced via HME platform at the pre-defined conditions, with maximum drug loadings of 0.65, 0.70 and 0.60 w/w for drug indomethacin, ibuprofen and naproxen respectively. Enhanced physical stability was further confirmed by high humidity (95%RH) storage stability studies. Through this work, we have demonstrated that by the implementation of predictive thermodynamic modelling, HDASD formulation design can be integrated into the HME process design to ensure the desired quality of the final dosage form.

A novel indomethacin/methotrexate/MMP-9 siRNA in situ hydrogel with dual effects of anti-inflammatory activity and reversal of cartilage disruption for the synergistic treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by inflammatory cell infiltration, and cartilage and bone disruption, which ultimately leads to loss of joint function. Current treatments for RA only focus on anti-inflammatory activity but neglect to prevent further damage to articular cartilage and bone. Here we attempted to co-deliver indomethacin (IND), methotrexate (MTX) and a small-interfering RNA targeting MMP-9 using an in situ hydrogel loaded with PEI-SS-IND-MTX-MMP-9 siRNA nanoparticles (D/siRNA-NGel) to treat RA synergistically and comprehensively. IND, MTX and MMP-9 siRNA were able to escape from the endosome and down-regulate the expression of MMP-9 and inflammatory cytokines of Raw-264.7 cells. After intra-articular injection in arthritic mice, the D/siRNA-NGel effectively relieved joint swelling and significantly reduced the expression of TNF-α, IL-6 and MMP-9 in the ankle fluid, knee joint fluid and plasma of RA mice without causing any side effects. Most importantly, the co-delivery system restored the morphological parameters of the ankle joints close to normal. The D/siRNA-NGel could achieve good anti-inflammatory activity and reverse cartilage disruption through a synergistic effect between chemical drugs and MMP-9 siRNA. This co-delivery system should have promising applications in the treatment of rheumatoid arthritis and other metabolic bone diseases which cause serious bone erosion.

Smart nanocrystal of indomethacin: Nanonization and characterization through top down method of media milling

Indomethacin is potent and effective drug belongs to NSAID group having low bioavailability. To address this issue the novel method is Nanosuspensions which can be achieved through bottom up and top down methods. The drug concentration, batch size and crystallinity retention are the problems associated with bottom up method consequently top down method was applied. In current project batch size of 350 ml was prepared by mixing 3.5% of Indomethacin with polymer solution. Then it was introduced into Dena⌖ having 0.2µm yttrium reinforced zirconium beads. The effect of milling time was observed for sixty minutes. Stable nanocrystals with particle size of 161nm ±1.90 with PDI of 0.229 ±0.06 were produced. The DSC and PXRD confirmed the crystallinity of created nanocrystals. The pattern of particle size reduction was initially abrupt and then gradual. The two months Stability studies at 4°C and at 25°C revealed that polymers combination (PVP-K30, HPMC-6cps, SDS) were effective in marinating the stability. The SEM and TEM studies unfastened that nanocrystals were homogenously distributed with discrete crystalline morphology. The fabricated nanocrystals demonstrated marked dissolution rate compared to the raw and marketed formulations. It is demonstrated that it is useful for industry due to high drug concentration, large batch size and retention of distinct characteristics.

The Aminoalkylindole BML-190 Negatively Regulates Chitosan Synthesis via the Cyclic AMP/Protein Kinase A1 Pathway in Cryptococcus neoformans

Cryptococcus neoformans can cause fatal meningoencephalitis in patients with AIDS or other immunocompromising conditions. Current antifungals are suboptimal to treat this disease; therefore, novel targets and new therapies are needed. Previously, we have shown that chitosan is a critical component of the cryptococcal cell wall and is required for survival in the mammalian host and that chitosan deficiency results in rapid clearance from the mammalian host. We had also identified several specific proteins that were required for chitosan biosynthesis, and we hypothesize that screening for compounds that inhibit chitosan biosynthesis would identify additional genes/proteins that influence chitosan biosynthesis. To identify these compounds, we developed a robust and novel cell-based flow cytometry screening method to identify small-molecule inhibitors of chitosan production. We screened the ICCB Known Bioactives library and identified 8 compounds that reduced chitosan in C. neoformans We used flow cytometry-based counterscreens and confirmatory screens, followed by a biochemical secondary screen to refine our primary screening hits to 2 confirmed hits. One of the confirmed hits that reduced chitosan content was the aminoalkylindole BML-190, a known inverse agonist of mammalian cannabinoid receptors. We demonstrated that BML-190 likely targets the C. neoformans G-protein-coupled receptor Gpr4 and, via the cyclic AMP (cAMP)/protein kinase A (PKA) signaling pathway, contributes to an intracellular accumulation of cAMP that results in decreased chitosan. Our discovery suggests that this approach could be used to identify additional compounds and pathways that reduce chitosan biosynthesis and could lead to potential novel therapeutics against C. neoformansIMPORTANCECryptococcus neoformans is a fungal pathogen that kills ∼200,000 people every year. The cell wall is an essential organelle that protects fungi from the environment. Chitosan, the deacetylated form of chitin, has been shown to be an essential component of the cryptococcal cell wall during infection of a mammalian host. In this study, we screened a set of 480 compounds, which are known to have defined biological activities, for activity that reduced chitosan production in C. neoformans Two of these compounds were confirmed using an alternative method of measuring chitosan, and one of these was demonstrated to impact the cAMP signal transduction pathway. This work demonstrates that the cAMP pathway regulates chitosan biosynthesis in C. neoformans and validates that this screening approach could be used to find potential antifungal agents.

Solid lipid nanoparticles self-assembled from spray dried microparticles

We report the self-assembly of drug-loaded solid lipid nanoparticles (SLNs) from spray dried microparticles comprising poly(vinylpyrrolidone) (PVP) loaded with glyceryl tristearate (GTS) and either indomethacin (IMC) or 5-fluorouracil (5-FU). When the spray dried microparticles are added to water, the PVP matrix dissolves and the GTS and drug self-assemble into SLNs. The SLNs provide a non-toxic delivery platform for both hydrophobic (IMC) and hydrophilic (5-FU) drugs. They show extended release profiles over more than 24 h, and in permeation studies the drug cargo is seen to accumulate inside cancer cells. This overcomes major issues with achieving local intestinal delivery of these active ingredients, in that IMC permeates well and thus will enter the systemic circulation and potentially lead to side effects, while 5-FU remains in the lumen of the small intestine and will be secreted without having any therapeutic benefit. The SLN formulations are as effective as the pure drugs in terms of their ability to induce cell death. Our approach represents a new and simple route to the fabrication of SLNs: by assembling these from spray-dried microparticles on demand, we can circumvent the low storage stability which plagues SLN formulations.

Cocrystal Solubility Advantage Diagrams as a Means to Control Dissolution, Supersaturation, and Precipitation

Cocrystals are often more soluble than needed and pose unnecessary risks for precipitation of less soluble forms of the drug during processing and dissolution. Such conversions lead to erratic cocrystal behavior and nullify the cocrystal solubility advantage over parent drug (SA = Scocrystal/Sdrug). This work demonstrates a quantitative method for additive selection to control cocrystal disproportionation based on cocrystal solubility advantage (SA) diagrams. The tunability of cocrystal SA is dependent on the selective drug-solubilizing power of surfactants (SPdrug = (ST/Saq)drug). This cocrystal property is used to generate SA-SP diagrams that facilitate surfactant selection and provide a framework for evaluating how SA influences drug concentration-time profiles associated with cocrystal dissolution, drug supersaturation, and precipitation (DSP). Experimental results with indomethacin-saccharin cocrystal and surfactants (sodium lauryl sulfate, Brij, and Myrj) demonstrate the log-linear relationship characteristic of SA-SP diagrams and the dependence of σmax and dissolution area under the curve (AUC) on SA with characteristic maxima at a threshold supersaturation where drug nucleation occurs. This approach is expected to streamline cocrystal formulation as it facilitates additive selection by considering the interplay between thermodynamic (SA) and kinetic (DSP) processes.

Self-Assembled Indomethacin Dimer Nanoparticles Loaded with Doxorubicin for Combination Therapy in Resistant Breast Cancer

An ortho-ester-linked indomethacin (IND) dimer-based nanodrug delivery system was prepared to improve the therapeutic effect of doxorubicin (DOX) by reversing the multidrug resistance. The synthesized dimer (IND-OE) could form stable nanoparticles (IND-OE/DOX) loaded with DOX via the single-emulsion method. Compare to insensitive nanoparticles (IND-C12/DOX), IND-OE/DOX showed a rapid degradation behavior and accelerated drug release at mildly acidic environments. In vitro cell experiments verified that IND-OE nanoparticles could increase DOX concentration due to the efficient intracellular drug release by the degradation of the ortho ester as well as reduced DOX efflux by IND-mediated P-gp downregulation. In vivo studies further demonstrated that IND-OE/DOX displayed the maximized synergetic antitumor efficacy than free DOX or IND-C12/DOX, and the tumor inhibition rates versus saline were 46.78% (free DOX), 60.23% (IND-C12/DOX), and 80.62% (IND-OE/DOX). Overall, this strategy of combination with chemosensitizers and ortho ester linkage has great potential to serve as an amplifying chemotherapy platform against various drug-resistant tumors.

Targeting the Shc-EGFR interaction with indomethacin inhibits MAP kinase pathway signalling

Receptor tyrosine kinase (RTK)-mediated hyperactivation of the MAPK/Erk pathway is responsible for a large number of pathogenic outcomes including many cancers. Considerable effort has been directed at targeting this pathway with varying degrees of long term therapeutic success. Under non-stimulated conditions Erk is bound to the adaptor protein Shc preventing aberrant signalling by sequestering Erk from activation by Mek. Activated RTK recruits Shc, via its phosphotyrosine binding (PTB) domain (ShcPTB), precipitating the release of Erk to engage in a signalling response. Here we describe a novel approach to inhibition of MAP kinase signal transduction through attempting to preserve the Shc-Erk complex under conditions of activated receptor. A library of existing drug molecules was computationally screened for hits that would bind to the ShcPTB and block its interaction with the RTKs EGFR and ErbB2. The primary hit from the screen was indomethacin, a non-steroidal anti-inflammatory drug. Validation of this molecule in vitro and in cellular efficacy studies in cancer cells provides proof of principle of the approach to pathway down-regulation and a potential optimizable lead compound.

Topography of Simulated Intestinal Equilibrium Solubility

Oral administration of a solid dosage form requires drug dissolution in the gastrointestinal tract before absorption. Solubility is a key factor controlling dissolution, and it is recognized that, within the intestinal tract, this is influenced by the luminal fluid pH, amphiphile content, and composition. Various simulated intestinal fluid recipes have been introduced to mimic this behavior and studied using a range of different experimental techniques. In this article, we have measured equilibrium solubility utilizing a novel four component mixture design (4CMD) with biorelevant amphiphiles (bile salt, phospholipid, oleate, and monoglyceride) within a matrix of three pH values (5, 6, and 7) and total amphiphile concentrations (11.7, 30.6, and 77.5 mM) to provide a topographical and statistical overview. Three poorly soluble drugs representing acidic (indomethacin), basic (carvedilol), and neutral (fenofibrate) categories have been studied. The macroscopic solubility behavior agrees with literature and exhibits an overall increasing solubility from low pH and total amphiphile concentration to high pH and total amphiphile concentration. Within the matrix, all three drugs display different topographies, which can be related to the statistical effect levels of the individual amphiphiles or amphiphile interactions on solubility. The study also identifies previously unreported three and four way factor interactions notably between bile salt, phospholipid, pH, and total amphiphile concentration. In addition, the results also reveal that solubility variability is linked to the number of amphiphiles and the respective ratios in the measurement fluid, with the minimum variation present in systems containing all four amphiphiles. The individual 4CMD experiments within the matrix can be linked to provide a possible intestinal solubility window for each drug that could be applied in PBPK modeling systems. Overall the approach provides a novel overview of intestinal solubility topography along with greater detail on the impact of the various factors studied; however, each matrix requires 351 individual solubility measurements. Further studies will be required to refine the experimental protocol in order the maximize information garnered while minimizing the number of measurements required.

Nanoshells prepared by atomic layer deposition - Long acting depots of indomethacin

There is a trend in pharmaceutical research and development to develop depot formulations with dosing once weekly, once monthly, or even less frequently. A novel approach to achieve long acting injectable suspensions is to produce dense inorganic nanoshells with atomic layer deposition (ALD) on active pharmaceutical ingredients. Such particles can be suspended in an aqueous vehicle and administered subcutaneously. The purpose of this work was to study the release of a model drug, indomethacin, coated with aluminium oxide nanoshells. Indomethacin was ball-milled to a median particle size of 6 µm. The nanoshells were produced with a proprietary ALD process that is trademarked as PharmaShell® by Nanexa AB. The drug load was determined with HPLC-UV to 82 wt%. The test materials were administered subcutaneously in rats (1, 10, and 100 mg/kg) from which blood samples were collected during 12 weeks. Plasma was generated and analyzed with regards to indomethacin using UPLC-MS/MS. The release rate was dramatically slower for the nanoshell coated indomethacin compared with uncoated indomethacin. Drug was released in vivo during more than 12 weeks for the 10 and 100 mg/kg doses, and during 10 weeks for the 1 mg/kg dose, while uncoated indomethacin was eliminated with a half-life of 15 h, as calculated from the release data by fitting a one phase decay function. The exposure levels were similar as earlier reported for therapeutic indomethacin doses, but significantly sustained in the present study using coated drug particles in rats. In conclusion, this is the first long-term in vivo evaluation of nanoshell depot formulations. The stable plasma concentrations for more than 12 weeks demonstrate that nanoshells can enable long-term depot injections with high drug load.

Facile Engineering of Indomethacin-Induced Paclitaxel Nanocrystal Aggregates as Carrier-Free Nanomedicine with Improved Synergetic Antitumor Activity

Carrier-free nanomedicines mainly composed of drug nanocrystals are considered as promising candidates for next-generation nanodrug formulations. However, such nanomedicines still need to be stabilized by additive surfactants, synthetic polymers, or biologically based macromolecules. Based on the strong intermolecular interactions between indomethacin (IDM, a COX-2 inhibitor) and paclitaxel (PTX, a chemotherapy drug), we herein successfully engineered a novel kind of carrier-free nanomedicines that organized as IDM-induced PTX nanocrystal aggregates via one-pot self-assembly without any nonactive excipients. In the assemblies of IDM and PTX (IDM/PTX assemblies), PTX nanocrystals were casted with amorphous IDM molecules, like a "brick-cement" architecture. In serum, these nanoassemblies could rapidly collapse into a great number of smaller nanoparticles, thus targeting the tumor site through the EPR effect. Under the assistance of IDM on immunotherapy, the IDM/PTX assemblies showed obviously improved synergetic antitumor effects of immunotherapy and chemotherapy. The self-assembly of two synergistic active substances into nanomedicines without any nonactive excipients might open an alternative avenue and give inspiration to fabricate novel carrier-free nanomedicines in many fields.

Thermo-activated peroxydisulfate oxidation of indomethacin: Kinetics study and influences of co-existing substances

The widespread occurrence of non-steroidal anti-inflammatory drugs (NSAIDs) (e.g., Indomethacin) in the ambient environment has attracted growing concerns due to their potential threats to ecosystems and human health. Herein, we investigated the degradation of indomethacin (IM) by thermo-activated peroxydisulfate (PDS). The pseudo first-order rate constant (k_obs) of degradation of IM was increased significantly with higher temperatures and PDS doses. Moreover, when the initial pH value was raised from 5 to 9 the IM degradation was initially decreased and then increased. Basic conditions were favorable for the removal of IM in the thermo-activated peroxydisulfate system. A response surface methodology based on the Box-Behnken design (BBD) was successfully employed for the optimization of the thermo-activated peroxydisulfate (PDS) system. The presence of chlorine ions manifested a dual effect on the degradation of IM, while bicarbonate and SRFA (as a NOM model) reduced it. Radical scavenging tests and electron spin resonance (ESR) revealed that the dominant oxidizing species were SO₄^- and OH at pH 9. Furthermore, the TOC removal efficiency attained 28.8% and the release of Cl^-was 38.5% at 60 °C within 24min, while the mineralization rate of IM were 85.5% with the PDS concentration up to 20  mM at 2 h oxidation. To summarize, thermo-activated PDS oxidation is a promising technique for the remediation of IM-contaminated water.

DSC, FTIR and Raman Spectroscopy Coupled with Multivariate Analysis in a Study of Co-Crystals of Pharmaceutical Interest

Co-crystals have garnered increasing interest in recent years as a beneficial approach to improving the solubility of poorly water soluble active pharmaceutical ingredients (APIs). However, their preparation is a challenge that requires a simple approach towards co-crystal detection. The objective of this work was, therefore, to verify to what extent a multivariate statistical approach such as principal component analysis (PCA) and cluster analysis (CA) can be used as a supporting tool for detecting co-crystal formation. As model samples, physical mixtures and co-crystals of indomethacin with saccharin and furosemide with p-aminobenzoic acid were prepared at API/co-former molar ratios 1:1, 2:1 and 1:2. Data acquired from DSC curves and FTIR and Raman spectroscopies were used for CA and PCA calculations. The results obtained revealed that the application of physical mixtures as reference samples allows a deeper insight into co-crystallization than is possible with the use of API and co-former or API and co-former with physical mixtures. Thus, multivariate matrix for PCA and CA calculations consisting of physical mixtures and potential co-crystals could be considered as the most profitable and reliable way to reflect changes in samples after co-crystallization. Moreover, complementary interpretation of results obtained using DSC, FTIR and Raman techniques is most beneficial.

Investigation of miscibility estimation methods between indomethacin and poly(vinylpyrrolidone-co-vinyl acetate)

The investigation of the miscibility between active pharmaceutical ingredients (API's) and polymeric excipients is of great interest for the formulation and development of amorphous solid dispersions, especially in the context of the prediction of the stability of these systems. Two different methods were applied to determine the miscibility between model compounds poly(vinylpyrrolidone-co-vinyl acetate) (PVPVA) and indomethacin (IND), viz. the measurement of the glass transition temperature (T_g) and the melting point depression method framed on the Flory-Huggins theory. Measurement of the glass transition temperatures of the binary blends showed the formation of an amorphous single phase system between the PVPVA and the IND regardless of the composition. Variation of T_g with the composition was well described by the Gordon-Taylor equation leading to the error of concluding lack of intermolecular interactions between the materials. Application of the Brostow-Chiu-Kalogeras-Vassilikou-Dova (BCKV) model shows a negative interaction parameter (a₀) suggesting the presence of drug-drug intermolecular interactions. Application of the melting point depression method within the framework of the Flory-Huggins theory proved the miscibility of the system at temperatures close to the melting point of IND.

Dendrimers for Drug Delivery

Dendrimers have come a long way in the last 25 years since their inception. Originally created as a wonder molecule of chemistry, dendrimer is now in the fourth class of polymers. Dr. Donald Tomalia first published his seminal work on Poly(amidoamine) (PAMAM) dendrimers in 1985. Application of dendrimers as a drug delivery system started in late 1990s. Dendrimers for drug delivery are employed using two approaches: (i) formulation and (ii) nanoconstruct. In the formulation approach, drugs are physically entrapped in a dendrimer using non-covalent interactions, whereas drugs are covalently coupled on dendrimers in the nanoconstruct approach. We have demonstrated the utility of PAMAM dendrimers for enhancing solubility, stability and oral bioavailability of various drugs. Drug entrapment and drug release from dendrimers can be controlled by modifying dendrimer surfaces and generations. PAMAM dendrimers are also shown to increase transdermal permeation and specific drug targeting. Dendrimer platforms can be engineered to attach targeting ligands and imaging molecules to create a nanodevice. Dendrimer nanotechnology, due to its multifunctional ability, has the potential to create next generation nanodevices.

A molecularly imprinted dual-emission carbon dot-quantum dot mesoporous hybrid for ratiometric determination of anti-inflammatory drug celecoxib

We report on a ratiometric fluorescent sensor based on dual-emission molecularly imprinted mesoporous silica embedded with carbon dots and CdTe quantum dots (mMIP@CDs/QDs) for celecoxib (CLX) as target molecule. The fluorescence of the embedded CDs is insensitive to the analyte while the green emissive QDs are selectively quenched by it. This effect is much stronger for the MIP than for the non-imprinted polymer, which indicates a good recognition ability of the mesoporous MIP. The hybrid sensor also exhibited good selectivity to CLX over other substances. The ratio of the intensity at two wavelengths (F₅₅₀/F₄₄₀) proportionally decreased with the increasing of CLX concentration in the range of 0.08-0.90μM. A detection limit as low as 57nM was achieved. Experimental results testified that this sensor was highly sensitive and selective for the detection of CLX in human serum samples.

Investigation of Ethylene Oxide-co-propylene Oxide for Dissolution Enhancement of Hot-Melt Extruded Solid Dispersions

The optimal design of amorphous solid dispersion formulations requires the use of excipients to maintain supersaturation and improve physical stability to ensure shelf-life stability and better absorption during intestinal transit, respectively. Blends of excipients (surfactants and polymers) are often used within pharmaceutical products to improve the oral delivery of Biopharmaceutical Classification System class II drugs. Therefore, in this study, a dissolution enhancer, poloxamer 407 (P407), was investigated to determine its effect on the dissolution properties and on the amorphous nature of the active pharmaceutical ingredient contained in the formulation. Phase solubility studies of indomethacin (INM) in aqueous solutions of P407 and poly(vinylpyrrolidone-vinyl acetate copolymer) showed an increase in the kinetic solubility of INM compared with the pure drug at 37°C with a K_a value of 0.041 μg/mL. The solid dispersions showed a higher dissolution rate when compared to pure and amorphous drugs when performed in pH buffer 1.2 with a kinetic solubility of 21 μg/mL. The stability data showed that the amorphous drug in solid solutions with poly(vinylpyrrolidone-vinyl acetate copolymer) and P407 remained amorphous, and the %P407 loading had no effect on the amorphous stability of INM. This study concluded that the amorphous solid dispersion contributed to the increased solubility of INM.