Chitosan - dextran phosphate carbamate hydrogels for locally controlled co-delivery of doxorubicin and indomethacin: From computation study to in vivo pharmacokinetics.

The development of synergistic drug combinations is a promising strategy for effective cancer suppression. Here, we report all-polysaccharide biodegradable polyelectrolyte complex hydrogels (DPCS) based on dextran phosphate carbamate (DP) and chitosan (CS) for controlled co-delivery of the anticancer drug doxorubicin (DOX) and the non-steroidal anti-inflammatory drug indomethacin (IND). IND can induce more apoptosis in tumor cells by reducing the level of multidrug resistance-associated protein 1. Based on calculations using density functional theory and zeta potential analysis data, carriers with high drug loading were obtained. The release profile of both drugs from the hydrogels was tuned by changing the molecular weight and functional groups content of the polysaccharides. The optimized DPCS showed a steady release of DOX both in vitro and in vivo, and a gradual release of IND, which constantly induced the action of DOX. Considering all of these benefits, DOX- and IND-loaded DPCS offer a promising long-acting polysaccharide-based antitumor platform.

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.

Effect of Counterions on Dissolution of Amorphous Solid Dispersions Studied by Surface Area Normalized Dissolution.

Solubility enhancement has become a common requirement for formulation development to deliver poorly water soluble drugs. Amorphous solid dispersions (ASDs) and salt formation have been two successful strategies, yet there are opportunities for further development. For ASDs, drug-polymer phase separation may occur at high drug loadings during dissolution, limiting the increase of drug loadings in ASD formulations. For salt formation, a salt form with high crystallinity and sufficient solid-state stability is required for solid dosage form development. This work studied the effect of counterions on the dissolution performance of ASDs. Surface area normalized dissolution or intrinsic dissolution methodology was employed to eliminate the effect of particle size and provide a quantitative comparison of the counterion effect on the intrinsic dissolution rate. Using indomethacin (IMC)-poly(vinylpyrrolidone-co-vinyl acetate) ASD as a model system, the effect of different bases incorporated into the ASD during preparation, the molar ratios between the base and IMC, and the drug loadings in the ASD were systematically studied. Strong bases capable of ionizing IMC significantly enhanced drug dissolution, while a weak base did not. A physical mixture of a strong base and the ASD also enhanced the dissolution rate, but the effect was less pronounced. At different base to IMC molar ratios, dissolution enhancement increased with the base to IMC ratio. At different drug loadings, without a base, the IMC dissolution rate decreased with the increase of drug loading. After incorporating a strong base, it increased with the increase of drug loading. The observations from this study were thought to be related to both the ionization of IMC in ASDs and the increase of microenvironment pH by the incorporated bases. With the significant enhancement of the drug dissolution rate, our work provides a promising approach of overcoming the dissolution limitation of ASD formulations at high drug loadings.

Lipid Formulations and Bioconjugation Strategies for Indomethacin Therapeutic Advances.

Indomethacin (IND) is a drug which after successful clinical trials became available for general prescription in 1965 and from that time is one of the most widely used anti-inflammatory drug with the highest potencies in the in vitro and in vivo models. However, despite its high therapeutic efficacy in relieving the symptoms of certain arthritis and in treating gout or collagen diseases, administration of IND causes a number of adverse effects, such as gastrointestinal ulceration, frequent central nervous system disorders and renal toxicity. These obstacles significantly limit the practical applications of IND and make that 10-20% of patients discontinue its use. Therefore, during the last three decades many attempts have been made to design novel formulations of IND aimed to increase its therapeutic benefits minimizing its adverse effects. In this review we summarize pharmacological information about IND and analyze its new lipid formulations and lipid bioconjugates as well as discuss their efficacy and potential application.

[Ocular Drug Delivery System-based on Solid Nanoparticles].

The use of eye drops is a well-established practice in the treatment of ophthalmic diseases, although the bioavailability of traditional eye drops, which are either solutions or suspensions, is insufficient, as the corneal barrier and dilution by lacrimation prevent the transcorneal penetration of drugs. Additionally, frequent instillation may cause undesirable systemic side effects and local corneal toxicity. To overcome these problems, micro- and nanoparticles, hydrogels, and viscous solutions have been tested, and solid nanoparticles are also expected to be applied. This review examines the usefulness of ophthalmic formulations based on solid nanoparticles, by using the specific example of indomethacin (IMC). Ophthalmic formulations based on solid IMC nanoparticles (IMC-NP dispersions) have been prepared using various additives (benzalkonium chloride, mannitol, methylcellulose, and cyclodextrin) and a rotation/revolution pulverizer (NP-100), to produce particles of 50-220 nm in size. The solubility of IMC in IMC-NP dispersions was 4.18-fold higher than that in the suspensions containing IMC microparticles (IMC-MP suspensions), and IMC-NP dispersions were better tolerated than commercially available NSAIDs eye drops, such as IMC, pranoprofen, diclofenac, bromfenac, and nepafenac eyedrops, in human corneal epithelial cells. Moreover, the corneal penetration in IMC-NP dispersions was higher than that in commercially available IMC and IMC-MP suspensions, and three energy-dependent endocytosis pathways (clathrin-dependent endocytosis, caveolae-dependent endocytosis, and macropinocytosis) were related to the high ophthalmic bioavailability of IMC-NP dispersions. This information can be used to support future studies aimed at designing novel ophthalmic formulations.

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.

Model based approach for estimating the dosage regimen of indomethacin a potential antiviral treatment of patients infected with SARS CoV-2.

To face SARS-CoV-2 pandemic various attempts are made to identify potential effective treatments by repurposing available drugs. Among them, indomethacin, an anti-inflammatory drug, was shown to have potent in-vitro antiviral properties on human SARS-CoV-1, canine CCoV, and more recently on human SARS-CoV-2 at low micromolar range. Our objective was to show that indomethacin could be considered as a promising candidate for the treatment of SARS-CoV-2 and to provide criteria for comparing benefits of alternative dosage regimens using a model-based approach. A multi-stage model-based approach was developed to characterize % of recovery and viral load in CCoV-infected dogs, to estimate the PK of indomethacin in dog and human using published data after administration of immediate (IR) and sustained-release (SR) formulations, and to estimate the expected antiviral activity as a function of different assumptions on the effective exposure in human. Different dosage regimens were evaluated for IR formulation (25 mg and 50 mg three-times-a-day, and 25 mg four-times-a-day), and SR formulation (75 mg once and twice-a-day). The best performing dosing regimens were: 50 mg three-times-a-day for the IR formulation, and 75 mg twice-a-day for the SR formulation. The treatment with the SR formulation at the dose of 75 mg twice-a-day is expected to achieve a complete response in three days for the treatment in patients infected by the SARS-CoV-2 coronavirus. These results suggest that indomethacin could be considered as a promising candidate for the treatment of SARS-CoV-2 whose potential therapeutic effect need to be further assessed in a prospective clinical trial.

Osthole inhibited the activity of CYP2C9 in human liver microsomes and influenced indomethacin pharmacokinetics in rats.

Osthol, a pharmacologically active ingredient in various traditional Chinese medicines, is predominantly metabolized by CYP2C9. It may be co-administered with other drugs which are metabolized by CYP2C9 in clinical medicine. However, CYP2C9*1/*2/*3 genotype on the pharmacokinetics of osthole and its metabolic diversity between rat and human are unclear.In this study, we investigated the effects of osthole on enzyme activity of CYP2C11/CYP2C9 in rat liver microsomes (RLMs) and human liver microsomes (HLMs), to distinguish metabolic manner of osthole in different species. Interestingly, we found that osthole inhibits the activity of CYP2C11 in a non-competitive manner in RLMs, while inhibits CYP2C9 activity in a competitive manner in pooled HLMs. Then, the effects of CYP2C9*1/*2/*3 allele on the pharmacokinetics of osthole were identified. In human CYP2C9 isoform, the Ki value of 21.93 µM (CYP2C9*1), 18.10 µM (CYP2C9*2), 13.12 µM (CYP2C9*3) indicate that there are individual differences in the inhibition of osthole on CYP2C9 activity.We investigated how the indomethacin pharmacokinetics was affected by osthole in SD rat. To estimate the area under the curve (AUC), maximum plasma concentration (Cmax) and apparent clearance (CL/F), indomethacin (10 mg/kg) was given orally combined with osthole (20 mg/kg) in adult SD rat. We found the value of PK on indomethacin, such as the AUC0-∞, was from 176.40 ± 17.29 to 173.74 ± 27.69 µg/ml h-1, Cmax from 9.02 ± 1.24 to 9.89 ± 0.82 µg/ml and CL/F from 0.11 ± 0.01 to 0.12 ± 0.04 mg/kg/h which were unsignificantly changed compared with the control groups. However, the Tmax was prolonged from 2.00 ± 0.00 h to 7.33 ± 1.15 h, and T1/2 increased from 8.38 ± 2.30 h to 11.37 ± 2.11 h. These results indicate that osthole could potentially affect the metabolism of indomethacin in vivo.

A sodium alginate/feather keratin composite fiber with skin-core structure as the carrier for sustained drug release.

To alleviate the serious gastrointestinal side reaction of indomethacin (IDM), sodium alginate/feather keratin (SA/FK) fiber with skin-core structure was prepared via wet spinning as the carrier for sustained release of IDM. Fourier translation infrared (FT-IR) spectroscopy was adopted to investigate the reaction mechanism among SA, FK and IDM, and Ultraviolet-visible (UV-Vis) spectroscopy was used to systematically evaluate the sustained release capacity of SA/FK fiber in three simulated fluids. Scanning electron microscope (SEM) was employed to observe the apparent morphology of SA/FK fiber. The results indicate that, release amount of IDM exhibits an increase trend along with time; the release amount of IDM reaches 80% after 12 h in colon fluid and small intestinal fluid, and is less than 20% in digestive fluid. Simultaneously, FK can effectively control the release of IDM, and with the increase of FK content, IDM release time of the carrier fiber extends.

Polymer/lipid interplay in altering in vitro supersaturation and plasma concentration of a model poorly soluble drug.

Supersaturation drug delivery system (SDDS) based on amorphous solid dispersion (ASD) is a widely used strategy to improve oral absorption of poorly water-soluble drugs by achieving a supersaturated state where drug concentration is significantly higher than drug solubility. However, dissolved drugs tend to recrystallize in gastrointestinal (GI) tract if without effective stabilizing excipients. In this paper, well-recognized polymer (polyvinylpyrrolidone, PVP) and lipid (phosphatidylcholine, PC) excipients are combined as ASD carrier, aiming at investigating the effects on evolution of in vitro supersaturation and in vivo plasma concentration of a model poorly soluble drug indomethacin (IND). Fundamental aspects including polymer/lipid composition ratio, drug loading (DL) degree and administration dose were investigated. The in vitro dissolution profiles of ASDs were assessed by supersaturation degree, duration, maximum achievable drug concentration and dose-normalized efficiency, and correlated with in vivo pharmacokinetic data. Results showed that both in vitro and in vivo concentration-time profiles of IND were significantly varying with abovementioned factors. Solution viscosity, solid-state properties and morphology of ASDs were related to the results. This study revealed fundamental mechanisms of PVP/PC mixture effect on IND supersaturation and oral bioavailability, demonstrating that polymer/lipid mixture could be used as a promising carrier to alter supersaturation profile and oral bioavailability of SDDS products.

Pharmacokinetics-based analysis of indomethacin's anti-tumor effect and drug efficacy.

Non-steroidal anti-inflammatory drugs are commonly used anti-inflammatory analgesics in clinic. Indomethacin is a kind of NSAIDs and has anti-tumor effect. It can significantly change the growth cycle of cancer cells, inhibit their proliferation. In this paper, the antineoplastic effect of indomethacin and its pharmacokinetic effect were analysed. The result showed that indomethacin had more metabolic distribution in tumor tissues and reached its peak at 4 hours, after that, the clearance rate was slower than that in the blood, with the clearance rate slowest at 6-12 hours. At the same time, the expression of Bcl-2 protein in cancer cells was significantly reduced and weakened, while the expression of Bax protein did not change significantly. Pharmacodynamic studies have proved that IN (Indomethacin) has a strong anti-tumor effect. It can enter into tumor cells through cell membrane and nuclear membrane to have an anti-tumor effect.

VITREOUS PROSTAGLANDIN E2 CHANGES AFTER TOPICAL ADMINISTRATION OF DICLOFENAC 0.1%, INDOMETHACIN 0.5%, NEPAFENAC 0.3%, AND BROMFENAC 0.09.

PURPOSE: To evaluate the vitreous concentration of different nonsteroidal anti-inflammatory drugs (NSAIDs) after topical administration and the related prostaglandin E2 (PGE2) levels in patients undergoing pars plana vitrectomy. METHODS: A prospective, randomized, investigator-masked study was performed. One hundred four patients scheduled for a pars plana vitrectomy for an epiretinal membrane or a macular hole were randomized to receive topical diclofenac 0.1%, indomethacin 0.5%, nepafenac 0.3%, bromfenac 0.09%, or placebo 3 days before surgery. At the beginning of surgery, a sample of undiluted vitreous was collected in each patient to assess NSAIDs concentration and PGE2 levels. RESULTS: The median vitreous concentrations were 203.35 (interquartile range 146.54-264.18) pg/mL for diclofenac, 243.45 (interquartile range 156.96-365.37) pg/mL for nepafenac, 438.21 pg/mL (interquartile range, 282.52-645.87) for its active metabolite amfenac, 350.14 (interquartile range, 290.88-481.95) pg/mL for indomethacin, and 274.59 (245.43-358.25) pg/mL for bromfenac. Vitreous PGE2 levels were significantly lower for all the NSAIDs groups compared with the control group (P < 0.001). A statistically significant higher vitreous PGE2 level was found in the diclofenac group compared with the other NSAIDs groups (P < 0.05). CONCLUSION: Topical NSAIDs achieve sufficient vitreous concentration to decrease vitreous PGE2 levels compared with the control group. The different efficacy in reducing PGE2 concentration may affect the management of posterior segment inflammation.

Active Micropump-Mixer for Rapid Antiplatelet Drug Screening in Whole Blood.

There is a need for scalable automated lab-on-chip systems incorporating precise hemodynamic control that can be applied to high-content screening of new more efficacious antiplatelet therapies. This paper reports on the development and characterization of a novel active micropump-mixer microfluidic to address this need. Using a novel reciprocating elastomeric micropump design, we take advantage of the flexible structural and actuation properties of this framework to manage the hemodynamics for on-chip platelet thrombosis assay on type 1 fibrillar collagen, using whole blood. By characterizing and harnessing the complex three-dimensional hemodynamics of the micropump operation in conjunction with a microvalve controlled reagent injection system we demonstrate that this prototype can act as a real-time assay of antiplatelet drug pharmacokinetics. In a proof-of-concept preclinical application, we utilize this system to investigate the way in which rapid dosing of human whole blood with isoform selective inhibitors of phosphatidylinositol 3-kinase dose dependently modulate platelet thrombus dynamics. This modular system exhibits utility as an automated multiplexable assay system with applications to high-content chemical library screening of new antiplatelet therapies.

Computer-assisted engineering of programmed drug releasing multilayer nanomedicine via indomethacin-mediated ternary complex for therapy against a multidrug resistant tumor.

Nanomedicine with programmed drug release can give full play to the synergistic effect of multi-component system in complicated tumor environment. However, the construction of these programmed drug delivery systems often depends on the sophisticated materials design and synthesis. In this study, we successfully designed an indomethacin (IND)-mediated ternary complex system based on a PEG cleavable polyethyleneimine (PEI), indomethacin (IND) and benzene ring containing chemotherapeutic drugs (such as paclitaxel (PTX), doxorubicin and docetaxel). Based on the difference of hydrophobicity in these components, these components were one-pot self-assembled into drug-loaded IND mediated PEGylation cleavable nanoassemblies (IPCNs) in multilayer structure. In drug-loaded IPCNs, PEG fragments, PEI/IND, and chemotherapeutic drug were respectively distributed from the out layer to core of nanomedicine. When drug-loaded IPCNs reached tumor site through EPR effect, the PEG fragment would firstly responsively release to the acidic tumor microenvironment to expose the intermediate layer of drug-loaded IPCNs that composed by mixture of PEI and IND for increasing the surface potential to promote the uptake by tumor cells. After entering cells, IND would be released faster than chemotherapeutic drug encapsulated in core to efficiently inhibit the expression of multidrug resistance protein 1 to reverse MDR of tumor cells before chemotherapeutic drug releasing. Contributed by the staged responsively releasing of PEG fragments, IND and encapsulated chemotherapeutic drug, the drug-loaded IPCNs exhibited a superior antitumor efficacy against A549/MDR tumor cells both in vitro and in vivo. STATEMENT OF SIGNIFICANCE: The way to develop programmed released drug delivery system is commonly relied on complicated material design and synthesis. Herein, under the computer-assist design, we successfully designed a ternary complex derived from indomethacin (IND), paclitaxel (PTX) and a pH-responsive PEGylated polyethyleneimine (PEG-s-PEI), and employed this ternary complex to successfully prepare a high drug loading and multilayer structured nanomedicine of PTX (PTX IPCNs). Contribute by the different location of PTX, IND and PEG-s-PEI in PTX IPCNs, PEG fragments, IND and PTX molecules could programmed release after reaching tumor for perfectly realizing the synergistic anti-tumor effect of tumor targeting, reversal of MDR and chemotherapy. Based on a fusion of these multiple mechanisms, PTX IPCNs showed a superior antitumor efficacy in mice loading A549/MDR tumor.

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.

Combination with l-Menthol Enhances Transdermal Penetration of Indomethacin Solid Nanoparticles.

This study designed the transdermal formulations containing indomethacin (IMC)-1% IMC was crushed with 0.5% methylcellulose and 5% 2-hydroxypropyl-ß-cyclodextrin by the bead mill method, and the milled IMC was gelled with or without 2% l-menthol (a permeation enhancer) by Carbopol® 934 (without menthol, N-IMC gel; with menthol, N-IMC/MT gel). In addition, the drug release, skin penetration and percutaneous absorption of the N-IMC/MT gel were investigated. The particle sizes of N-IMC gel were approximately 50-200 nm, and the combination with l-menthol did not affect the particle characterization of the transdermal formulations. In an in vitro experiment using a Franz diffusion cell, the skin penetration in N-IMC/MT gel was enhanced than the N-IMC gel, and the percutaneous absorption (AUC) from the N-IMC/MT gel was 2-fold higher than the N-IMC gel. On the other hand, the skin penetration from the N-IMC/MT gel was remarkably attenuated at a 4 °C condition, a temperature that inhibits all energy-dependent endocytosis. In conclusion, this study designed transdermal formulations containing IMC solid nanoparticles and l-menthol, and found that the combination with l-menthol enhanced the skin penetration of the IMC solid nanoparticles. In addition, the energy-dependency of the skin penetration of IMC solid nanoparticles was demonstrated. These findings suggest the utility of a transdermal drug delivery system to provide the easy application of solid nanoparticles (SNPs).

Effect of Tetrabutylammonium Bromide-Based Deep Eutectic Solvents on the Aqueous Solubility of Indomethacin at Various Temperatures: Measurement, Modeling, and Prediction with Three-Dimensional Hansen Solubility Parameters.

Deep eutectic solvents (DESs) have recently been getting a great deal of attention in many fields of science and technology. The objective of this study was to peruse the solubility of indomethacin (IMC) as sparingly soluble drug in some tetrabutylammonium bromide (TBAB)-based DESs (TBAB/ethylene glycol and TBAB/glycerol). The shake flask method has been employed in this study at temperature ranges T = (298.15-313.15) K and atmospheric pressure (pP = 86.6 kPa). The results showed that the solubility of IMC in TBAB/ethylene glycol system was obtained approximately 17,000-fold more than its solubility in water. The solubility data were accurately correlated by the famous local composition activity coefficient models including e-NRTL and UNIQUAC. It was also our aim to evaluate Hansen solubility parameters in IMC solubility prediction. These parameters can help to predict the solvent performance during the manufacturing processes and will be useful in guessing solvent behavior in many other fields of effort. The experimental and the Hansen solubility parameters results are very well matched. In addition, the apparent thermodynamic properties of dissolution and mixing were studied in these solutions based on Van't Hoff and Gibbs equations.

Impacts of Polymeric Additives on Nucleation and Crystal Growth of Indomethacin from Supersaturated Solutions.

Three polymers, polyvinylpyrrolidone (PVP K30), hydroxypropyl methyl cellulose (HPMC E5), and Kollidone VA64 (PVP-VA64), have been assessed for their impact on the nucleation and crystal growth of indomethacin (IND) from supersaturation solutions. PVP was the most effective inhibitor on IND nucleation among three polymers, but the effect of three polymers on inhibiting nucleation is quite limited when the degree of supersaturation S is higher than about 9. Analysis of the nucleation data by classical nucleation theory model generally afforded good data fitting with the model and showed that addition of polymers may affect the crystal/solution interfacial free energy γ and also the pre-exponential kinetic factor. PVP-VA showed better inhibitory effects on crystal growth of IND when the polymer concentration is high (0.1%, w/w) as reflected by the crystal growth inhibition factor R, and PVP exhibited relatively stronger effects on inhibiting crystal growth at low polymer concentrations (0.005%, w/w). The crystal growth inhibitory effect of polymers should be attributable to the retardation of the surface integration of the drug, and such effect should also be polymer and drug dependent. The enhancement of supersaturation level of IND should be attributable to both nucleation and crystal growth inhibition by polymers. The nucleation and crystal growth rate of α-polymorph IND is higher than that of γ-polymorph, and α-polymorph is the predominant form appeared in supersaturated solutions. A rational selection of the appropriate polymer for specific drug is critical for developing supersaturated drug delivery formulations.

Energy-dependent endocytosis is responsible for drug transcorneal penetration following the instillation of ophthalmic formulations containing indomethacin nanoparticles.

PURPOSE: We previously found that ophthalmic formulations containing nanoparticles prepared by a bead mill method lead to an increase in bioavailability in comparison with traditional formulations (solution type). However, the transcorneal penetration pathway for ophthalmic formulations has not been explained yet. In this study, we investigated the mechanism of transcorneal penetration in the application of ophthalmic formulations containing indomethacin nanoparticles (IMC-NPs). MATERIALS AND METHODS: IMC-NPs was prepared by the bead mill method. For the analysis of energy-dependent endocytosis, corneal epithelial (HCE-T) cell monolayers and removed rabbit cornea were thermoregulated at 4°C, where energy-dependent endocytosis is inhibited. In addition, for the analysis of different endocytosis pathways using pharmacological inhibitors, inhibitors of caveolae-mediated endocytosis (54 µM nystatin), clathrin-mediated endocytosis (40 µM dynasore), macropinocytosis (2 µM rottlerin) or phagocytosis (10 µM cytochalasin D) were used. RESULTS: The ophthalmic formulations containing 35-200 nm sized indomethacin nanoparticles were prepared by treatment with a bead mill, and no aggregation or degradation of indomethacin was observed in IMC-NPs. The transcorneal penetration of indomethacin was significantly decreased by the combination of nystatin, dynasore and rottlerin, and the decreased penetration levels were similar to those at 4°C in HCE-T cell monolayers and rabbit cornea. In the in vivo experiments using rabbits, dynasore and rottlerin tended to decrease the transcorneal penetration of indomethacin (area under the drug concentration - time curve in the aqueous humor [AUCAH]), and the AUCAH in the nystatin-treated rabbit was significantly lower than that in non-treatment group. In addition, the AUCAH in rabbit corneas undergoing multi-treatment was obviously lower than that in rabbit corneas treated with each individual endocytosis inhibitor. CONCLUSION: We found that three energy-dependent endocytosis pathways (clathrin-dependent endocytosis, caveolae-dependent endocytosis and macropinocytosis) are related to the trans-corneal penetration of indomethacin nanoparticles. In particular, the caveolae-dependent endocytosis is strongly involved.

Exploring the use of spray congealing to produce solid dispersions with enhanced indomethacin bioavailability: In vitro characterization and in vivo study.

The current study proposes an original oral delivery system for the bioavailability enhancement of indomethacin (IND), a BCS class II drug, with the aim to overcome the common limitations of amorphous solid dispersion. In fact, the potential risk of drug re-crystallization is a serious concern for the stability of amorphous systems and represents, despite the great bioavailability, one of the primary causes of their limited clinical applications. IND-loaded microparticles (MPs) were prepared by spray congealing using oral-approved excipients (Gelucire 50/13 and the recently marketed Gelucire 48/16). MPs were characterized regarding particle size, morphology, drug content and IND solid state; moreover, they were tested in vitro for IND solubility and dissolution rate. Solid state characterization indicated that IND was present into the MPs in the amorphous form. The best formulation showed a considerable enhancement in drug dissolution rate and 31-fold higher drug solubility than pure γ-IND. The oral administration of MPs showed 2.5-times increased bioavailability in vivo compared to either pure γ-IND or its physical mixture with unloaded MPs. Notably, the formulation was stable after 18 months with no changes in IND solid state and dissolution performance. This study offers a valid approach to enhance IND oral bioavailability by conversion into the amorphous form by spray congealed MPs, which have great potential for industrial application due to their characteristics of high encapsulation efficiency, no-toxicity, low-cost, prolonged stability and the use of a simple and easily scaled-up manufacturing technology.