Eudragit RL 100-based nanoparticulate system of aceclofenac for ocular delivery

Fabrication and evaluation of lipid nanoparticulates for ocular delivery of a COX-2 inhibitor

CONTEXT

The unique physiological limitations of the eye have been assigned as reason of low bioavailability by conventional drug delivery systems. There is need of such drug carriers, which ensure improved bioavailability as well as patient compliance upon instillation into the eye.

OBJECTIVE

The present investigation deals with development of solid lipid nanoparticles (SLNs) containing celecoxib (CXB) for treatment of ophthalmic inflammations.

MATERIALS AND METHODS

The SLNs were formulated by melt-emulsion sonication and low temperature-solidification process and evaluated for particle size, surface morphology, physicochemical properties, percentage drug incorporation efficiency, in vitro drug release, in vitro trans-corneal permeation, in vivo efficacy in ocular inflammation, stability study and gamma scintigraphy study to assess the residence of solid lipid nanoparticles over ocular surfaces.

RESULTS

The SLNs were spherical and the optimized formulation had particle size of 198.77 ± 7.5 nm, which is quite suitable for ocular applications. The maximum entrapment efficiency of 92.46 ± 0.07% was achieved for formulation SLN 20. The permeation across the cornea was also significantly better than aqueous suspension (8.21 ± 0.67 versus 4.61 ± 0.71) at p < 0.05.

DISCUSSION AND CONCLUSION

The SLN formulations demonstrated improved performance of entrapped CXB while mitigating the key parameters of ocular inflammation in rabbits. The particulate formulations have exhibited prolonged retention over ocular surfaces as evident from results of gamma scintigraphy using ^99mTc labeled SLNs.

Plant extracts: from encapsulation to application

INTRODUCTION

Plants are a natural source of various products with diverse biological activities offering treatment for several diseases. Plant extract is a complex mixture of compounds, which can have antioxidant, antibiotic, antiviral, anticancer, antiparasitic, antifungal, hypoglycemic, anti-hypertensive and insecticide properties. The extraction of these extracts requires the use of organic solvents, which not only complicates the formulations but also makes it difficult to directly use the extracts for humans. To overcome these problems, recent research has been focused on developing new ways to formulate the plant extracts and delivering them safely with enhanced therapeutic efficacy.

AREAS COVERED

This review focuses on the research done in the development and use of polymeric nanoparticles for the encapsulation and administration of plant extracts. It describes in detail, the different encapsulation techniques, main physicochemical characteristics of the nanoparticles, toxicity tests and results obtained from in vivo or in vitro assays.

EXPERT OPINION

Major obstacles associated with the use of plant extracts for clinical applications include their complex composition, toxicity risks and extract instability. It is observed that encapsulation can be successfully used to decrease plant extracts toxicity, to provide targeted drug delivery and to solve stability related problems.

Design and Evaluation of Voriconazole Loaded Solid Lipid Nanoparticles for Ophthalmic Application

Voriconazole is a second-generation antifungal agent with excellent broad spectrum of antifungal activity commercially available for oral and intravenous administration. Systemic administration of voriconazole is associated with side effects including visual and hepatic abnormalities. This study assessed the feasibility of using solid lipid nanoparticles for ocular delivery of voriconazole adopting stearic acid as lipidic material, tween 80 as a stabilizer, and Carbopol 934 as controlled release agent and for increasing the precorneal residence time in eye. The systems were prepared using two different methods, that is, ultrasonication method and microemulsion technique. The results indicated that the larger particle size of SLNs was found with microemulsion technique (308 ± 3.52 nm to 343 ± 3.51) compared to SLN prepared with ultrasonication method (234 ± 3.52 nm to 288 ± 4.58 nm). The polydispersity index values were less than 0.3 for all formulations and zeta potential of the prepared formulations by these two methods varied from −22.71 ± 0.63 mV to −28.86 ± 0.58 mV. Powder X-ray diffraction and differential scanning calorimetry indicated decrease in crystallinity of drug. The in vitro release study and the SLN formulations prepared with ultrasonication method demonstrated sustained release up to 12 hours. This study demonstrated that SLN prepared by ultrasonication method is more suitable than microemulsion technique without causing any significant effect on corneal hydration level.

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.

Design, characterization and in vitro evaluation of novel shell crosslinked poly(butylene adipate)-co-N-succinyl chitosan nanogels containing loteprednol etabonate: A new system for therapeutic effect enhancement via controlled drug delivery

This study reports on the development of a novel mucoadhesive and biocompatible shell-crosslinked nanogel system based on poly(butylene adipate) (PBA) and N-succinyl chitosan (S-Cs) by coupling reaction with a new formulation method. For this purpose, two different molecular weights of dendrimerized PBA with amine terminated functional groups were synthesized separately and characterized well by FT-IR, (1)HNMR and GPC. The PBA nanoparticles containing loteprednol etabonate (LPE) prepared by O/W emulsion technique were reacted immediately with modified carboxylated chitosan via carbodiimide chemistry. TEM photographs of the nanoparticles and crosslinked nanoparticles displayed a spherical morphology closely corresponding to the results obtained by DLS. On The other hand, biodegradability, biocompatibility and bioadhesiveness of the prepared nanoparticles were also studied. It is concluded that the core-shell structured nanogels can be used as novel ocular drug delivery systems with appropriate loading capacity for slightly water soluble LPE as an anti-inflammatory drug.

Evaluation of gatifloxacin pluronic micelles and development of its formulation for ocular delivery

The purpose of the present study was to enhance the solubility of gatifloxacin by developing self-assembling pluronic micelles of gatifloxacin for ocular delivery, to overcome the problem of poor bioavailability and therefore lesser therapeutic response exhibited by conventional ophthalmic solutions of the drug. Gatifloxacin was loaded in micelles by solid dispersion method using Pluronic F127 and evaluated for particle size, drug loading, loading efficiency, in vitro transcorneal permeation study, in vitro drug release, solubility studies, microbiological studies, ex vivo mucoadhesive strength, and ocular safety studies. The drug loading and drug loading efficiency studies revealed that gatifloxacin/Pluronic F127 ratio of 0.25/2.52 g offered good drug loading (9.96 %), high loading efficiency (90 %), and acceptable particle size of 176 nm (polydispersity index 0.345). Hen's egg test chorioallantoic membrane (HET-CAM) assay with 0 score in 8 h and ocular safety test with score of 2 indicate the nonirritant property of the developed pluronic micelles. In vitro transcorneal permeation studies through excised goat cornea indicated increase in ocular availability with no corneal damage. In vitro drug release data of optimized formulation provided sustained release over a period of 8 h. Optimized formulation was found to possess acceptable transcorneal permeation and antimicrobial efficacy when compared to marketed eye drops. The solubility studies of gatifloxacin from these lyophilized pluronic micelles revealed 18.67-fold increase in comparison to gatifloxacin suspension in water. The pluronic micelles could enhance ocular bioavailability of gatifloxacin, prolong its residence time in the eyes, and may lead to reduced instillation frequency, thereby resulting in better patient compliance.

Synthesis of hybrid polymer blend nanoparticles and incorporation into in situ gel foam spray for controlled release therapy using a versatile synthetic purine nucleoside analogue antiviral drug

Antiviral drug loaded nanoparticles is incorporated intoin situgel for controlled release therapy. Chemical and physical interactions of drug and polymers in the system influenced their characteristics and drug release mechanism.

Stem Cell Therapy for Corneal Regeneration Medicine and Contemporary Nanomedicine for Corneal Disorders

The ocular surface is the outermost part of the visual system that faces many extrinsic or intrinsic threats, such as chemical burn, infectious pathogens, thermal injury, Stevens-Johnson syndrome, ocular pemphegoid, and other autoimmune diseases. The cornea plays an important role in conducting light into the eyes and protecting intraocular structures. Several ocular surface diseases will lead to the neovascularization or conjunctivalization of corneal epithelium, leaving opacified optical media. It is believed that some corneal limbal cells may present stem cell-like properties and are capable of regenerating corneal epithelium. Therefore, cultivation of limbal cells and reconstruction of the ocular surface with these limbal cell grafts have attracted tremendous interest in the past few years. Currently, stem cells are found to potentiate regenerative medicine by their capability of differentiation into multiple lineage cells. Among these, the most common cell sources for clinical use are embryonic, adult, and induced stem cells. Different stem cells have varied specific advantages and limitations for in vivo and in vitro expansion. Other than ocular surface diseases, culture and transplantation of corneal endothelial cells is another major issue for corneal decompensation and awaits further studies to find out comprehensive solutions dealing with nonregenerative corneal endothelium. Recently, studies of in vitro endothelium culture and ρ-associated kinase (ROCK) inhibitor have gained encouraging results. Some clinical trials have already been finished and achieved remarkable vision recovery. Finally, nanotechnology has shown great improvement in ocular drug delivery systems during the past two decades. Strategies to reconstruct the ocular surface could combine with nanoparticles to facilitate wound healing, drug delivery, and even neovascularization inhibition. In this review article, we summarized the major advances of corneal limbal stem cells, limbal stem cell deficiency, corneal endothelial cell culture/transplantation, and application of nanotechnology on ocular surface reconstruction. We also illustrated potential applications of current knowledge for the future treatment of ocular surface diseases.