The stenlying effect of high hydrostatic pressure on thermally and hydrolytically labile nanosized carriers

Nanopharmaceuticals for Eye Administration: Sterilization, Depyrogenation and Clinical Applications

Simple Summary

Nanopharmaceuticals have revolutionized the way ophthalmic drugs are administered to overcome ocular delivery barriers and improve drug bioavailability. The design and production of an efficient ocular drug delivery system still remain a challenge. In this review, we discuss the sterilization and depyrogenation methods, commonly used for ophthalmic nanopharmaceuticals, and their clinical applications.

Abstract

As an immune-privileged target organ, the eyes have important superficial and internal barriers, protecting them from physical and chemical damage from exogenous and/or endogenous origins that would cause injury to visual acuity or even vision loss. These anatomic, physiological and histologic barriers are thus a challenge for drug access and entry into the eye. Novel therapeutic concepts are highly desirable for eye treatment. The design of an efficient ocular drug delivery system still remains a challenge. Although nanotechnology may offer the ability to detect and treat eye diseases, successful treatment approaches are still in demand. The growing interest in nanopharmaceuticals offers the opportunity to improve ophthalmic treatments. Besides their size, which needs to be critically monitored, nanopharmaceuticals for ophthalmic applications have to be produced under sterilized conditions. In this work, we have revised the different sterilization and depyrogenation methods for ophthalmic nanopharmaceuticals with their merits and drawbacks. The paper also describes clinical sterilization of drugs and the outcomes of inappropriate practices, while recent applications of nanopharmaceuticals for ocular drug delivery are also addressed.

Potential implications of nanoparticle characterization on in vitro and in vivo gene delivery

Nanoparticles are rapidly emerging as therapeutic delivery vectors defined by size-dependent properties. They offer several advantages over the traditional drug-delivery systems and medical diagnostics but also pose considerable challenges for systemic applications. Gene delivery is one of the important applications of nanotechnology. Usually, the nanoparticles employed for gene delivery are either formed by condensation of DNA with preformed cationic polymers or by polymerization of monomeric units thereby entrapping DNA in it. The physicochemical properties such as size, shape, surface morphology have been found to have significant influence on the gene-delivery efficacy of nanoparticles. Furthermore, when administered in vitro and in vivo, the efficiency of nanoparticles depends on a wide variety of other parameters, that is, transfection conditions, time of exposure, cell type and so forth. In this review, the potential role of characterization of nanoparticles physicochemical properties on the in vitro and in vivo gene delivery efficacy of nanoparticles is discussed.

Preparação de nanopartículas poliméricas a partir de polímeros pré-formados: parte II

Nanopartículas poliméricas produzidas a partir de polímeros pré-formados, como os poliésteres alifáticos, têm sido amplamente utilizadas para incorporar, principalmente, princípios ativos lipofílicos. A produção das nanopartículas (nanocápsulas e nanosferas) por polímeros pré-formados pode ser realizada por emulsificação-evaporação do solvente, por deslocamento do solvente, por salting-out ou por emulsificação-difusão do solvente. Estes métodos de produção estão revisados e descritos neste artigo, evidenciando os parâmetros tecnológicos que interferem nas características físico-químicas das nanopartículas, como a solubilidade do princípio ativo, o volume e pH do meio de polimerização, a massa molar e concentração do monômero e a natureza e concentração do tensoativo.

Methods for the preparation and manufacture of polymeric nanoparticles

This review summarizes the different methods of preparation of polymer nanoparticles including nanospheres and nanocapsules. The first part summarizes the basic principle of each method of nanoparticle preparation. It presents the most recent innovations and progresses obtained over the last decade and which were not included in previous reviews on the subject. Strategies for the obtaining of nanoparticles with controlled in vivo fate are described in the second part of the review. A paragraph summarizing scaling up of nanoparticle production and presenting corresponding pilot set-up is considered in the third part of the review. Treatments of nanoparticles, applied after the synthesis, are described in the next part including purification, sterilization, lyophilization and concentration. Finally, methods to obtain labelled nanoparticles for in vitro and in vivo investigations are described in the last part of this review.

Design aspects of poly(alkylcyanoacrylate) nanoparticles for drug delivery

Poly(alkylcyanoacrylate) (PACA) nanoparticles were first developed 25 years ago taking advantage of the in vivo degradation potential of the polymer and of its good acceptance by living tissues. Since then, various PACA nanoparticles were designed including nanospheres, oil-containing and water-containing nanocapsules. This made possible the in vivo delivery of many types of drugs including those presenting serious challenging delivery problems. PACA nanoparticles were proven to improve treatments of severe diseases like cancer, infections and metabolic disease. For instance, they can transport drugs across barriers allowing delivery of therapeutic doses in difficult tissues to reach including in the brain or in multidrug resistant cells. This review gives an update on the more recent developments and achievements on design aspects of PACA nanoparticles as delivery systems for various drugs to be administered in vivo by different routes of administration.

Sterile, injectable cyclodextrin nanoparticles: effects of gamma irradiation and autoclaving

Sterility is required as stated by compendial requirements and registration authorities worldwide for an injectable drug carrier system. In this study, injectable nanospheres and nanocapsules prepared from amphiphilic beta-cyclodextrin, beta-CDC6, were assessed for their in vitro properties such as particle size distribution, zeta potential, nanoparticle yield (%), drug entrapment efficiency and in vitro drug release profiles. Different sterilization techniques such as gamma irradiation and autoclaving were evaluated for their feasibility regarding the maintenance of the above mentioned nanoparticle properties after sterilization. It was found that amount these techniques, sterilization with gamma irradiation seemed to be the most appropriate technique with no effect on particle size, drug loading and drug release properties. Gamma irradiation causes some chemical changes on beta-CDC6 observed as changes in zeta potential but this does not lead to any significant changes for nanoparticle properties. Autoclaving caused massive aggregation for the nanoparticles followed by precipitation, which led to the conclusion that excessive heat disrupted nanoparticle integrity. Sterile filtration was not feasible since nanoparticle sizes were larger than the filter pore size and the yield after sterilization was very low. Thus, it can be concluded that blank and drug loaded beta-CDC6 nanospheres and nanocapsules are capable of being sterilized by gamma irradiation.

Isostatic Ultra-High-Pressure Effects on Supercooled Melts in Colloidal Triglyceride Dispersions

PURPOSE

Colloidal triglyceride dispersions can form metastable supercooled melts that need tedious tempering processes to be transformed into a crystalline state. We investigated the possibility of transforming the supercooled melts into crystals in a short time by treatment with isostatic high pressure.

METHODS

Nanosized supercooled melts of triglycerides in aqueous dispersions (prepared by high-pressure homogenization) were exposed to isostatic ultrahigh pressure for short periods to initialize crystallization processes. The dispersions were analyzed with different appropriate measuring methods such as differential scanning calorimetry, nuclear magnetic resonance, X-ray scattering, and electron paramagnetic resonance. The resulting particle sizes were estimated by photon correlation spectroscopy and transmission electron microscopy.

RESULTS

The results of differential scanning calorimetry, X-ray, and nuclear magnetic resonance experiments show the induction of triglyceride particle crystallization by high-pressure treatment. Electron paramagnetic resonance spectroscopy shows that the triglyceride crystallization coincides with relocation of the lipophilic probe into a more polar environment. Transmission electron microscopy micrographs show the transformation of supercooled liquid particles into crystallized anisotropic particles.

CONCLUSION

Crystal transformation in nanoscaled systems can be delayed for months, depending on the materials and the composite. It is shown that isostatic high-pressure treatment can be a valuable method to induce, accelerate, and control crystallization processes in specific colloidal triglyceride dispersions.

Effects of high hydrostatic pressure on several sensitive therapeutic molecules and a soft nanodispersed drug delivery system

PURPOSE

According to the development in the last decade of industrial processes using high hydrostatic pressure (HHP) for preservation of several commercial food products, novel sterilization or decontamination processes for pharmaceutical products could be conceivable. The aim of this work is to evaluate the effects of HHP on the integrity of insulin and heparin solutions, suspension of monoclonal antibodies and Spherulites.

METHODS

High performance liquid chromatography, thin layer chromatography, capillary electrophoresis assays, ELISA tests, laser granulometry and spectrophotometry analyses have been performed to compare HHP treated drugs (in a domain of pressure and temperature ranging respectively from 20 up to 500 MPa and from 20 degrees C up to 37 degrees C) vs. untreated ones.

RESULTS

No difference has been detected except for monoclonal antibodies that are altered above 500 MPa.

CONCLUSIONS

The structure integrity of sensitive molecule due to the small energy involved by HHP and the development of industrial plants (intended for the decontamination of food products) confer to this technology the potential of a new method for sterilization of fragile drugs and an original alternative to aseptic processes and sterilizing filtration.