Comparison of cytotoxicityin vitroand irritationin vivofor aqueous and oily solutions of surfactants

Suspensions of antibiotics in self-emulsifying oils as a novel approach to formulate eye drops with substances which undergo hydrolysis in aqueous environment

The aim of this study was to develop eye-drops with cefuroxime (CEF) sodium or vancomycin (VAN) hydrochloride, antibiotics that are instable in water. Anhydrous self-emulsifying oils (SEO) are proposed as a carrier and antibiotics are suspended. In the contact with tear fluid, the formulation should transform into emulsion, with fast dissolution of an antibiotic. CEF or VAN (5% w/w) was suspended in SEO carriers prepared by dissolving surfactants (Tween 20 or Span 80 5% w/w) in Miglyol, castor oil, or olive oil. Formulations with or without sodium citrate (2% w/w) were compared. Six-months or 1-year stability tests were carried out at 40 °C. The content of CEF and VAN was evaluated using HPLC and the potency of the antibiotic was assessed with agar diffusion method. In contact with water, drug particles suspended in SEO dissolved rapidly and o/w emulsion was formed. After 1-year at 40 °C, the content of degradation products was at most 0.5% in CEF and 4.0% in VAN formulations. The agar diffusion assay has shown that CEF and VAN loaded into SEO retained its potency against the sensitive microorganisms comparable to an aqueous solution. Therefore, SEO can be used as a novel carrier for the active substances which may not require improved solubility or absorption but need to be protected from moisture. This is a formulation that can be produced on industrial scale, with no limitation of stability or drug concentration.

Microscopic and Biopharmaceutical Evaluation of Emulsion and Self-Emulsifying Oil with Cyclosporine

Among the currently available commercial eye drops with cyclosporine A (Cs) there is a lack of long-acting dosage forms and products with a concentration of the drug substance higher than 0.1%, although Cs is widely used in ophthalmology. The aim of the research was to conduct the microscopic and biopharmaceutical evaluation of two formulations, an emulsion (EM) and a self-emulsifying oil (SEO), both with 0.5% of Cs, proposed for use in eye drops, and the comparison of both. SEO eye drops with Cs or any other drug substance are currently not available as marketed products, and the highest concentration of Cs in the ocular emulsion is only 0.1%. The microscopic evaluation of the emulsion and the SEO after emulsification with water was carried out using a high-resolution digital microscopy. The properties of both preparations were compared using the high dynamic range function or optical shadow effect mode. Images in the 3D composition mode were also recorded. The in vivo study of the Cs formulations was performed on male albino rabbits. The eye tolerance of the preparations was assessed using the ocular irritation test, which is a modified Draize test. Placebo carriers (without the drug substance) were also subjected to irritation testing. The concentration of Cs in the tissues (cornea and conjunctiva) and fluids (tear fluid and aqueous humor) of the rabbit eye was determined after multiple instillations of Cs-EM or Cs-SEO. The tested preparations were compared using the digital microscopy technique, which highlights the features of the formulations and eliminates the risk of unnoticeable properties that are difficult to observe in classical optical microscopy. Both tested Cs-loaded formulations are classified as practically non-irritating. There were also no significant differences when testing the placebo carriers. After a topical administration, Cs was widely distributed in all tissues (e.g., in cornea 1.3 ng/mg and 1.0 ng/mg) and fluids of the eye (e.g., in tear fluid 11.6 µg/mL and 4.3 µg/mL), after the administration of Cs-SEO and Cs-EM, respectively. The obtained results allow us to recognize both tested formulations, the emulsion and the self-emulsifying oil with 0.5% Cs content, as carriers safe for ophthalmic use and effective in delivering the drug substance to the structures of the eye.

Polysorbate-Based Drug Formulations for Brain-Targeted Drug Delivery and Anticancer Therapy

Polysorbates (PSs) are synthetic nonionic surfactants consisting of polyethoxy sorbitan fatty acid esters. PSs have been widely employed as emulsifiers and stabilizers in various drug formulations and food additives. Recently, various PS-based formulations have been developed for safe and efficient drug delivery. This review introduces the general features of PSs and PS-based drug carriers, summarizes recent progress in the development of PS-based drug formulations, and discusses the physicochemical properties, biological safety, P-glycoprotein inhibitory properties, and therapeutic applications of PS-based drug formulations. Additionally, recent advances in brain-targeted drug delivery using PS-based drug formulations have been highlighted. This review will help researchers understand the potential of PSs as effective drug formulation agents.

Ocular penetration of fluorometholone-loaded PEG-PLGA nanoparticles functionalized with cell-penetrating peptides

Aim: Development of fluorometholone-loaded PEG-PLGA nanoparticles (NPs) functionalized with cell-penetrating peptides (CPPs) for the treatment of ocular inflammatory disorders. Materials & methods: Synthesized polymers and peptides were used for elaboration of functionalized NPs, which were characterized physicochemically. Cytotoxicity and ability to modulate the expression of proinflammatory cytokines were evaluated in vitro using human corneal epithelial cells (HCE-2). NPs uptake was assayed in both in vitro and in vivo models. Results: NPs showed physicochemical characteristics suitable for ocular administration without evidence of cytotoxicity. TAT-NPs and G2-NPs were internalized and displayed anti-inflammatory activity in both HCE-2 cells and mouse eye. Conclusion: TAT-NPs and G2-NPs could be considered a novel strategy for the treatment of ocular inflammatory diseases of the anterior and posterior segment.

An integrated microfluidic flow-focusing platform for on-chip fabrication and filtration of cell-laden microgels

We present the development of a stable continuous, and integrated microfluidic platform for the high-throughput fabrication of monodisperse cell-laden microgel droplets with high and maintained cellular viability. This is through combining onto one chip all the required processes from the droplet generation in a flow focusing microfluidic junction passing through on-chip photocrosslinking to the separation of the droplets from the continuous oil phase. To avoid cellular aggregation during the droplet generation process, cells were treated with bovine serum albumin (BSA) before mixing with gelatin methacrylate (GelMA). And, a magnetic mixer was applied to the GelMA prepolymer-cell suspension syringe to eliminate cell sedimentation. These approaches resulted in having a reasonable distribution of cells among monodisperse microdroplets. The microdroplets were irradiated with a 405 nm wavelength laser beam while passing through the crosslinking chamber of the microfluidic device. The produced microgels enter the filtration unit of the same device where they were gently separated from the oil phase into the washing buffer aqueous solution of Tween 80 using the filter microposts array. The viability of the encapsulated cells was around 85% at day 1 and was maintained throughout 5 days. Using this method of controlling cell encapsulation with on-chip crosslinking and oil filtration, highly efficient cell-laden microgel production is achieved. The presented integrated microfluidic platform can be a candidate for standard cell-encapsulation experiments and other tissue engineering applications.

Ocular irritation and cyclosporine A distribution in the eye tissues after administration of Solid Lipid Microparticles in the rabbit model

The aim of this study was to investigate the in vivo effect of Solid Lipid Microparticles (SLM), proposed for topical ocular administration of cyclosporine, on the rabbit eye. SLM carrier is an aqueous dispersion of lipid microparticles (20% w/w) with a size up to 15 μm. Cyclosporine was dissolved in the formulation in the concentration of 0.5 or 2.0% (w/w). Ocular tolerance of microsphere dispersion was assessed in rabbit model by the Draize eye test (SLM was compared with emulsion and oily solution), and cyclosporine distribution in ocular tissues was evaluated after multiple application of tested formulations (SLM dispersions, emulsions and oily solution) for 7 days. Good tolerance of cyclosporine-SLM formulation was demonstrated in the rabbit model. Concentration of cyclosporine in the precorneal tissues, such as cornea and conjunctiva, was much higher than the therapeutic value (8.4 ng/mg and 3.2 ng/mg, respectively). After SLM administration, the cyclosporine concentrations determined in the anterior ocular tissues, were also significantly higher compared to those obtained after the application of other tested carriers (emulsions and oily solution). The obtained results prove that the recognized SLM dispersions are safe formulations for ophthalmic use. It can be concluded that lipid microparticles are highly promising for an efficient ophthalmic drug delivery, when compared to other conventional dosage forms.

Formulation of polysaccharide-based nanoparticles for local administration into the oral cavity

The efficacy of treatments for oral ailments is often challenged by a low residence time of the conventional pharmaceutical formulations in the oral cavity. The residence time in the oral cavity could be improved by using bioadhesive formulations, such as preparations based on polysaccharides. This study describes the formulation and the evaluation of polysaccharide-based nanosystems as drug delivery systems addressed to the oral cavity. Nanoparticles based on chitosan, alginate or pectin were prepared through self-assembly by ionotropic gelation using oppositely charged crosslinkers (tripolyphosphate or zinc). Characteristics of nanoparticles at increasing crosslinker concentration provided the basis for selecting the most suitable formulations. The nanoparticles were tested for cytotoxicity against buccal cells (TR146) and for stability in a medium simulating pH, ionic strength, electrolyte composition and concentration of saliva. Alginate nanoparticles were the most stable in the salivary environment, while chitosan nanoparticles were the most cytocompatible. Alginate nanoparticles and pectin nanoparticles revealed possible cytotoxicity due to the presence of zinc. This knowledge is important in the early design of polymer-based nanoparticles for oral usage and for potential improving of the biocompatibility of the investigated nanoparticles with the oral environment.