Piroxicam nanoparticles for ocular delivery: physicochemical characterization and implementation in endotoxin-induced uveitis

To investigate the anti-inflammatory impacts of piroxicam nanosuspension, in the current investigation, piroxicam:Eudragit RS100 nanoformulations were used to control inflammatory symptoms in the rabbits with endotoxin-induced uveitis (EIU). The nanoparticles of piroxicam:Eudragit RS100 was formulated using the solvent evaporation/extraction technique. The morphological and physicochemical characteristics of nanoparticles were studied using particle size analysis, X-ray crystallography, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Drug release profiles were examined by fitting the data to the most common kinetic models. Selected nanosuspensions were used to assess the anti-inflammatory impacts of piroxicam nanoparticles in the rabbits with EIU. The major symptoms of EIU (i.e. inflammation and leukocytes numbers in the aqueous humor) were examined. All the prepared piroxicam formulations using Eudragit RS100 resulted in a nano-range size particles and displayed spherical smooth morphology with positively charged surface, however, the formulated particles of drug alone using same methodology failed to manifest such characteristics. The Eudragit RS100 containing nanoparticles displayed lower crystallinity than piroxicam with no chemical interactions between the drug and polymer molecules. Kinetically, the release profiles of piroxicam from nanoparticles appeared to fit best with the Weibull model and diffusion was the superior phenomenon. The in vivo examinations revealed that the inflammation can be inhibited by the drug:polymer nanosuspension more significantly than the microsuspension of drug alone in the rabbits with EIU. Upon these findings, we propose that the piroxicam:Eudragit RS100 nanosuspensions may be considered as an improved ocular delivery system for locally inhibition of inflammation.     

Preparation and characterization of polymeric and lipid nanoparticles of pilocarpine HCl for ocular application

Pilocarpine is used topically in the treatment of glaucoma. Various studies were performed to improve the bioavailability and prolong the residence time of drugs in ocular drug delivery. Drug loaded polymeric and lipid nanoparticles offer several favourable biological properties, such as biodegradability, nontoxicity, biocompatibility and mucoadhesiveness. Therefore, preparing positively-charged pilocarpine HCl-loaded polymeric and lipid nanoparticles was the purpose of this study. Nanoparticles were prepared by quasi-emulsion solvent evaporation technique. The non-biodegradable positively-charged polymer Eudragit^® RS 100 and semi-solid lipid excipient Gelucire^® 44/14 were used as a vehicle, the cationic lipid octadecylamine was used as a cationic agent. The formulations were evaluated in terms of particle size, size distribution, zeta potential measurement, thermal behavior (Differential Scanning Calorimetry DSC), entrapment efficacy and pH. Characterizations of nanoparticles were analyzed during the storage period of 6 months for stability tests. Polymeric and lipid nanoparticles could be prepared successfully promising their use for ophthalmic delivery.     

Chitosan nanoparticles for drug delivery to the eye

The purpose of this review is to provide the reader with an overview of the advances made in ocular delivery of bioactive molecules by means of chitosan-based nanosystems, and their potential relevance in clinical use. The studies described clearly emphasise that chitosan-based nanostructures are versatile systems that can be tailor-made according to required compositions, surface characteristics and particle size. Such parameters, which are known to influence their in vivo performance, can be modulated by adjusting the formulation conditions of the nanotechnologies responsible for their formation, by incorporating additional materials in the preparation steps, and/or by using synthetically modified chitosan. Moreover, this review illustrates how the advances achieved in the understanding of the interaction of nanosystems with the ocular structures should result in the coming years, logically, into challenging innovations in ocular nanomedicines with significant impact on clinical practice.     

Nanocarriers for ocular delivery for possible benefits in the treatment of anterior uveitis: focus on current paradigms and future directions

Introduction: Many therapeutic strategies have been adopted in the treatment of anterior uveitis, and it includes corticosteroids and NSAIDs. But, the successful delivery of these drugs is restricted due to limitations of conventional formulation. This review emphasizes on the possible benefits and strategies for development of various novel nanocarriers.

Areas covered: The article explores the various polymers involved in the preparation of novel nanocarriers like polymeric nanoparticles, micelles, microemulsion, liposomes and cubosomes. Reported clinical experimental findings are screened and also discussed in this review.

Expert opinion: The principle behind the development of different nanocarriers is to overcome the limitations imposed by conventional formulations. Several efforts have been made by the researchers in achieving these objectives, but the major challenge with nanosystems remains the requirement of excipients that have unknown or objectionable toxicity profile and are not approved by regulatory authorities. This review is an attempt to provide comprehensive information for the scientists working in the concerned research area.     

Evaluation of anti-inflammatory impact of dexamethasone-loaded PCL-PEG-PCL micelles on endotoxin-induced uveitis in rabbits

The aim of this study was to investigate the capability of polycaprolactone-polyethylene glycol-polycaprolactone (PCL-PEG-PCL) micelles in improving the anti-inflammatory effects of dexamethasone (DEX). A film hydration method was used for the preparation of the DEX-loaded PCL-PEG-PCL micelles. In vitro cytotoxicity of the micelles obtained was investigated on L929 cells. Cellular uptake was studied by using flow cytometry and fluorescence microscopy. Anterior uveitis was induced in a group of rabbits by intravitreal injection of endotoxin from Salmonella typhimurium. The severity of inflammation-induced was clinically graded by using Hogan’s classification method. Protein concentration in the aqueous humor was also measured. The micelles exhibited suitable compatibility on L929 cells and were taken up by the cells in a concentration- and time-dependent manner. The DEX-loaded micelles could reduce the clinical symptoms of uveitis after a lag-time. At 24 and 36?h after the LPS injection, the PCL-PEG-PCL micelles showed a better inhibitory effect on uveitis than the marketed eye drop, the differences did not reach significant levels though. This study demonstrated the potential of the PCL-PEG-PCL micelles as carriers for DEX in treating anterior uveitis. However, this concept is still to be further investigated.     

Development of gatifloxacin-loaded cationic polymeric nanoparticles for ocular drug delivery

The present investigation aimed at improving the ocular bioavailability of gatifloxacin by prolonging its residence time in the eye and reducing problems associated with the drug re-crystallization after application through incorporation into cationic polymeric nanoparticles. Gatifloxacin-loaded nanoparticles were prepared via the nanoprecipitation and double emulsion techniques. A 50:50 Eudragit® RL and RS mixture was used as cationic polymer with other formulation parameters varied. Prepared nanoparticles were evaluated for size, zeta potential, and drug loading. An optimized formulation was selected and further characterized for in vitro drug release, cytotoxicity, and antimicrobial activity. The double emulsion method produced larger nanoparticles than the nanoprecipitation method (410?nm and 68?nm, respectively). Surfactant choice also affected particle size and zeta potential with Tween 80 producing smaller-sized particles with higher zeta potential than PVA. However, the zeta potential was positive at all experimental conditions investigated. The optimal formulation produced by double emulsion technique and has achieved 46% drug loading. This formulation had optimal physicochemical properties with acceptable cytotoxicity results, and very prolonged release rate. The particles antimicrobial activities of the selected formulation have been tested against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus and showed prolonged antimicrobial effect for gatifloxacin.     

Effect of a selective inducible nitric oxide synthase inhibitor on intraocular nitric oxide production in endotoxin-induced uveitis rabbits: in vivo intraocular microdialysis study

Inducible nitric oxide (NO) synthase (iNOS) is believed to contribute to the pathogenesis of endotoxin-induced uveitis (EIU). In the present study, we investigated the inhibitory effects of N(G)-nitro-L-arginine methyl ester (L-NAME), a non-selective NOS inhibitor, and S,S'-1,4-phenylene-bis(1,2-ethanediyl)bis-isothiourea (PBITU), a potent and selective iNOS inhibitor, on intraocular NO production in EIU rabbits using an in vivo intraocular microdialysis technique. The flare level in the anterior chamber increased from 1h after the injection of 100 micro g/kg lipopolysaccharide (LPS), and continued to increase for 24h. Aqueous humor protein concentrations were significantly increased at 24h after LPS-injection. These changes were significantly reduced by L-NAME (10mg/kg) and PBITU (1mg/kg), but not by D-NAME (10mg/kg). The increase in NO(2)(-) and NO(3)(-) levels in the dialysate induced by LPS was significantly inhibited by L-NAME (10mg/kg) and PBITU (1mg/kg), but not by D-NAME (10mg/kg). These results suggest that activation of iNOS may play a key role in the development of EIU, and selective inhibitors of iNOS may have therapeutic applications in the treatment of EIU.     

Cubic liquid crystalline nanoparticles: optimization and evaluation for ocular delivery of tropicamide

The purpose of this study was to investigate the potential of cubic liquid crystalline nanoparticles for ocular delivery of tropicamide. Ultrasound-assisted fragmentation of cubic liquid crystalline bulk phases resulted in cubic liquid crystalline nanoparticles employing Pluronic F127 as dispersant. The effects of process variables such as sonication time, sonication amplitude, sonication depth, and pre-mixing time on particle size and polydispersity index was investigated using central composite design. The morphology of tropicamide-loaded nanoparticles was found to be nearly cubical in shape by transmission electron microscopy observation. Further, small angle X-ray scattering experiment confirmed the presence of D and P phase cubic structures in coexistence. The optimized tropicamide-loaded cubic nanoparticles showed in vitro corneal permeation of tropicamide across isolated porcine cornea comparable to its commercial preparation, Tropicacyl®. Ocular tolerance was evaluated by Hen’s egg–chorioallantoic membrane test and histological studies. The results of in vivo mydriatic response study demonstrated a remarkably higher area under mydriatic response curve (AUC_0→1440?min) values of cubic nanoparticles over Tropicacyl® indicating better therapeutic value of cubic nanoparticles. Furthermore, tropicamide-loaded cubic nanoparticles exhibited prolonged mydriatic effect on rabbits as compared to commercial conventional aqueous ophthalmic solution.     

Sustained-release solid dispersion of pelubiprofen using the blended mixture of aminoclay and pH independent polymers: preparation and in vitro/in vivo characterization

The present study aimed to develop the sustained-release oral dosage form of pelubiprofen (PEL) by using the blended mixture of 3-aminopropyl functionalized-magnesium phyllosilicate (aminoclay) and pH-independent polymers. The sustained-release solid dispersion (SRSD) was prepared by the solvent evaporation method and the optimal composition of SRSD was determined as the weight ratio of drug: Eudragit® RL PO: Eudragit® RS PO of 1:1:2 in the presence of 1% of aminoclay (SRSD(F6)). The dissolution profiles of SRSD(F6) were examined at different pHs and in the simulated intestinal fluids. The drug release from SRSD(F6) was limited at pH 1.2 and gradually increased at pH 6.8, resulting in the best fit to Higuchi equation. The sustained drug release from SRSD(F6) was also maintained in simulated intestinal fluid at fasted-state (FaSSIF) and fed-state (FeSSIF). The structural characteristics of SRSD(F6) were examined by using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR), indicating the change of drug crystallinity to an amorphous form. After oral administration in rats, SRSD(F6) exhibited the prolonged drug exposure in plasma. For both PEL and PEL-transOH (active metabolite), once a day dosing of SRSD(F6) achieved oral exposure (AUC) comparable to those from the multiple dosing (3 times a day) of untreated drug. In addition, the in vivo absorption of SRSD(F6) was well-correlated with the in vitro dissolution data, establishing a good level A in vitro/in vivo correlation. These results suggest that SRSD(F6) should be promising for the sustained-release of PEL, thereby reducing the dosing frequency.     

Eudragit S100 microparticles containing Spodoptera frugiperda nucleopolyehedrovirus: Physicochemical characterization,photostability and in vitro virus release

The aim of this study was to encapsulate the occlusion bodies (OBs) of Spodoptera frugiperda nucleopolyhedrovirus (SfNPV) in Eudragit® S100 microparticles (MPs), considering this technique as a possible alternative to protect them from deleterious environmental conditions. The MPs were prepared by oil-in-oil emulsion (O/O) solvent evaporation method. Experimental conditions were established according to a previous multi-level experimental design involving the core/polymer ratio as independent variable. The effects of these parameters on particle size and process yield were investigated observing that polymer concentration had a significant effect on particle size. After adequate conditions for MPs formation were determined, virus was encapsulated. The virus microparticles presented a particle size between 50–300 µm and concentration was 2.62 × 10⁹ OBs g^?1. Microencapsulation efficiency was 53.43% and virus release adjusted to Higuchi model suggesting diffusion as the release mechanism. Evaluated microencapsulation process protected viral particles of UV-inactivation, suggesting its potential for a biopesticide development.     

Microsphere-based once-daily modified release matrix tablets for oral administration in angina pectoris

The objective of this research was to develop microsphere-based once-daily modified release tablet formulations of diltiazem hydrochloride (DH), a potent calcium channel blocker used in angina pectoris. For this purpose, DH-loaded microspheres were prepared by the solvent evaporation technique using Eudragit®RS 100. The effect of variation in the drug/polymer ratio on the physical and release characteristics of the microspheres was investigated. After the selection of the suitable microspheres, tablets were compressed using Compritol®888 ATO, Ludipress® and Cellactose®80 as different direct tableting agents and excipients. As a result, modified release tablet formulations of DH-loaded microspheres were designed successfully for oral administration once rather than two or three times a day in angina pectoris.     

PLGA nanoparticles for intravitreal peptide delivery: statistical optimization,characterization and toxicity evaluation

Abstract

Frequent intravitreal injections are currently used to overcome the ocular barriers and provide sufficient drug to the posterior eye segment. However, intravitreal injections have been associated with a number of complications and high treatment costs. To overcome these limitations, peptide-loaded poly(d,l-lactic-co-glycolic acid) nanoparticles (PLGA NPs) were developed using the nanoprecipitation technique and were optimized via Box–Behnken Design (BBD) and Response Surface Methodology (RSM). Developed NPs were evaluated for potential toxicity and cell apoptosis using the zebrafish embryo toxicity (ZET) model with titanium dioxide NPs and ethanol (1% v/v) serving as positive controls. Developed NPs had a size of 75.6–153.8?nm, a polydispersity index between 0.11 and 0.25 and a zeta potential of ?9.4 to ?46.0?mV. Loaded peptide was found to be stable under various experimental conditions tested. BBD and RSM were validated through the characterization of optimized formulations. Survival and hatching rates of NP-treated zebrafish 0–144?h post-fertilization were found to be normal with no significant malformations. Cellular apoptosis studies also endorsed the non-cytotoxic nature of the NPs. The overall results indicate that optimized PLGA nanoparticles could be a promising platform for efficient peptide delivery to the posterior segment of the eye.     

眼部的给药屏障和给药途径

近年来,眼部药物递送系统越来越受到重视,本文综述了目前眼部给药的主要屏障包括角膜、结膜屏障,血房水屏障、血视网膜屏障等,以及一些新的给药途径和给药方法如结膜下、巩膜给药和离子电渗疗法等。以环孢素A为例介绍了一些克服眼部屏障的给药方法。尽管眼部给药系统目前已取得了进展,但药物递送到眼的后段仍有较大的难度,需要进一步开发更有效的眼部药物递送系统。     

Physicochemical characterization and toxicological evaluation of plant-based anionic polymers and their nanoparticulated system for ocular delivery

The water-soluble fractions of mucilages and gum from the seeds of fenugreek, isphagula and mango bark exudate were isolated, purified and characterized using X-ray diffraction (XRD) spectrometry, Fourier transform infrared spectroscopy (FT-IR), maldi/GC-MS, elemental analysis, 1D (¹H and ¹³C) and 2D (HMQC, COSY) nuclear magnetic resonance spectroscopy (NMR). The fenugreek mucilage was identified to be a galactomannan chain consisting of 4 units of galactose attached to the backbone of 6 mannose units in 1:1.5 ratio. The isphagula mucilage was identified to be an arabinoxylan polysaccharide chain consisting of 4 units of arabinofuranose attached to the backbone of 9 xylopyrannose units in 1:3 ratio. The mango gum showed the presence of amylose, α-arabinofuranosyl and β-galactopyranosyl, respectively. The characterized mucilages and gum were individually formulated into nanoparticulate system using their complementarily charged polymer chitosan. The particles were observed to be spherical in shape in the range of 61.5–90 nm having zetapotential between 31 and 34 mV and PDI of 0.097–0.241. The prepared nanoparticles were observed to be nonirritant and nontoxic in vitro and in vivo upto 2000 μg/ml. Therefore, these mucilages and gum can be the alternatives of anionic polymers for the ocular drug delivery system.     

Ocular delivery of cyclosporine A based on glyceryl monooleate/poloxamer 407 liquid crystalline nanoparticles: preparation,characterization, in vitro corneal penetration and ocular irritation

The purpose of this study was to develop an ophthalmic drug delivery system for cyclosporine A (CsA) based on glyceryl monooleate (GMO)/poloxamer 407 liquid crystalline nanoparticles with reduced ocular irritancy and improved corneal penetration. CsA-loaded liquid crystalline nanoparticles were prepared via fragmentation of a bulk GMO/poloxamer 407 cubic phase gel by high-pressure homogenization and characterized. Corneal permeation and retention was evaluated using modified Franz diffusing cells. Intra-corneal transportation was investigated with fluorescein isothiocyanate (FITC)-labeled liquid crystalline nanoparticles. Ocular irritation was then evaluated using the Draize method. The mean particle size of liquid crystalline nanoparticles was 193.5?nm and the entrapment efficiency was 95.11?±?0.67%. A bicontinuous cubic phase of cubic P-type was determined using cryo-transmission electron microscopy (cryo-TEM) observation and small angle X-ray diffraction (SAXD) analysis. A 1.52-fold increase in J_s and a 2.2-fold increase in corneal retention was achieved by liquid crystalline nanoparticles compared with oil solution. In vitro corneal permeation investigated with FITC-labeled liquid crystalline nanoparticles revealed that CsA penetrated across the cornea under the transportation of liquid crystalline nanoparticles. Liquid crystalline nanoparticles exhibited excellent ocular tolerance in the ocular irritation test. This low-irritant vehicle based on liquid crystalline nanoparticles might be a promising system for effective ocular CsA delivery.     

Design,characterization, and evaluation of aceclofenac-loaded Eudragit RS 100 nanoparticulate system for ocular delivery

The aim of the present study was to develop and evaluate positively charged nanoparticles of aceclofenac for ocular delivery. The nanoparticles were prepared by the nanoprecipitation method using Eudragit RS 100. The optimized nanoparticles were found to have narrow particle size range (238.9?±?8?nm) with nearly spherical shape, positive zeta potential (40.3?±?3.8). Higher entrapment efficiency of aceclofenac (94.53?±?1.0%) with prolonged in vitro drug release profiles was also observed. Powder X-ray diffraction and differential scanning calorimetry studies indicated decrease in crystallinity of drug within the nanoparticulate polymeric matrix. The formulation was found to have higher permeation as compared to aceclofenac aqueous solution. Nanoparticle formulation was found to be quite stable and well tolerated with no signs of corneal damage. The in vivo studies involving the arachidonic acid-induced ocular inflammation in rabbits showed optimal efficacy of the nanoparticles with significantly higher inhibition of polymorphonuclear leukocytes migration (p?<?0.05) and lid closure scores.     

Spotlight on the delivery of photosensitizers: different approaches for photodynamic-based therapies

Introduction: Nanomedicine development allowed the discovery of new photosensitizers (PS) and drug delivery systems (DDS) to overcome current issues on phototherapy. Nano-engineered materials have the potential to improve the solubility of PS, control drug pharmacokinetics, decreasing side effects, increasing bioavailability, and overcoming multidrug resistance. A recent approach is the co-delivery of PS with other therapeutic agents in a multimodal platform for synergic and improved results.

Areas covered: This paper discusses the delivery of PS-nanostructured platforms for conventional, photothermal, and antimicrobial photodynamic therapies, as well as in a recent therapeutic modality for photobiomodulation, covering applications of cancer diagnosis, targeting to skin pathogens, photoregeneration and wound healing. The focus of the present review is to describe the use of different DDS to enhance the therapeutic outcomes triggered by the combination of delivered PS, light, and oxygen.

Expert opinion: Nanotechnology allowed the development of site-specific delivery of PS molecules, expanding possibilities poorly explored before to enhance photodynamic efficacy and extrapolate the concept to other treatment protocols. Research in this area embraces potential and pitfalls of PS delivery, allowing new clinical phase outcomes and long-term issues to be established, which will impact on several biomedical applications.     

Chitosan nanoparticles for daptomycin delivery in ocular treatment of bacterial endophthalmitis

Abstract

Context: Chitosan nanoparticles were prepared to encapsulate daptomycin and proposed as a delivery system of this antibiotic to the eye for the treatment of bacterial endophthalmitis.

Objective: The aim of this study was to develop daptomycin-loaded nanoparticles to apply directly to the eye, as a possible non-invasive and less painful alternative for the treatment of endophthalmitis, increasing the effectiveness of treatment and reducing toxicity associated with systemic administration.

Materials and methods: Nanoparticles were obtained by ionotropic gelation between chitosan and sodium tripolyphosphate (TPP). Physicochemical and morphological characteristics of nanoparticles were evaluated, as well as determination of antimicrobial efficiency of encapsulated daptomycin and stability of the nanoparticles in the presence of lysozyme and mucin.

Results: Loaded nanoparticles presented mean particle sizes around 200?nm, low polydispersity index, and positive zeta potential. Morphological examination by scanning electron microscopy (SEM) confirmed their small size and round-shaped structure. Encapsulation efficiency ranged from 80 to 97%. Total in vitro release of daptomycin was obtained within 4?h. Determination of minimum inhibitory concentrations (MICs) showed that bacteria were still susceptible to daptomycin encapsulated into the nanoparticles. Incubation with lysozyme did not significantly affect the integrity of the nanoparticles, although mucin positively affected their mucoadhesive properties.

Discussion and conclusion: The obtained nanoparticles have suitable characteristics for ocular applications, arising as a promising solution for the topical administration of daptomycin to the eye.     

Formulation and evaluation of Cyclosporin A emulgel for ocular delivery

Abstract

Emulgels have been extensively covered as a promising drug delivery system for the administration of lipophilic drugs. This work was conducted to develop an emulgel formulation for Cyclosporin A (CsA) employing polycarbophil as the gelling agent for ocular delivery. The prepared emulgels were evaluated for their physical appearance, rheological behavior, drug release, stability, precorneal clearance and irritation. Results showed that CsA emulgel formulations prepared with polycarbophil exhibited acceptable physical properties and drug release, which remained consistent after storage for 3 months. A prolonged retention time was also observed on the ocular surface with improved ocular bioavailability and no irritation. Therefore, the polycarbophil-based emulgel could be exploited as a potential hydrophobic drug carrier for topical ocular drug delivery.