Effects of formulation variables on characteristics of poly (ethylcyanoacrylate) nanocapsules prepared from w/o microemulsions

Lamotrigine loaded poly-ɛ-(d,l-lactide-co-caprolactone) nanoparticles as brain delivery system

Management of epilepsy requires brain delivery therapy, therefore, this study was aimed to prepare lamotrigine loaded poly-ɛ-(d,l-lactide-co-caprolactone) (PLCL) nanoparticles using spontaneous emulsification solvent diffusion method. Nanoparticles for brain delivery required to have a particle size <200 nm, polydispesity index <0.2 and a sustained drug release properties. For such aim different factors were considered in preparing the nanoparticles as PLCL monomers' ratio, type of organic solvent used to prepare the nanoparticles, amount of PLCL and Pluronic®F127 in the nanoparticles. Prepared nanoparticles were characterized for their shape, particle size, polydispersity index, zeta potential, encapsulation efficiency, drug loading capacity, process yield and in-vitro drug release pattern. The in-vivo investigation for brain delivery of selected nanoparticles delivered by intravenous route was investigated in rats and compared to that for oral tablet. The obtained nanoparticles were spherical in shape. The amount of surfactant and PLCL affected the properties of the obtained nanoparticles. Using a mixture of organic solvent in preparing the nanoparticles improved its properties. The nanoparticles prepared using PLCL with monomers' ratio of 25:75, had particle size value of 125 nm, polydispersity index value of 0.184, zeta potential value of -39 mV and encapsulation efficiency value of 99%, was selected to study their efficacy to deliver the drug to the brain. The tested nanoparticles showed higher values of T_max, C_max, AUC, and MRT in homogenized rat brain, compared to oral lamotrigine tablet, while the bioavailability of the oral tablet was higher in rat plasma compared to that for the nanoparticles. This reflects that brain was the main distribution site for tested nanoparticles, and plasma was the main distribution site for oral tablets. This confirms the goal of the selected formulation as brain delivery nanoparticles.

Development and evaluation of injectable nanosized drug delivery systems for apigenin

The purpose of this study was to develop different injectable nanosized drug delivery systems (NDDSs) i.e. liposome, lipid nanocapsule (LNC) and polymeric nanocapsule (PNC) encapsulating apigenin (AG) and compare their characteristics to identify the nanovector(s) that can deliver the largest quantity of AG while being biocompatible. Two liposomes with different surface characteristics (cationic and anionic), a LNC and a PNC were prepared. A novel tocopherol modified poly(ethylene glycol)-b-polyphosphate block-copolymer was used for the first time for the PNC preparation. The NDDSs were compared by their physicochemical characteristics, AG release, storage stability, stability in serum, complement consumption and toxicity against a human macrovascular endothelial cell line (EAhy926). The diameter and surface charge of the NDDSs were comparable with previously reported injectable nanocarriers. The NDDSs showed good encapsulation efficiency and drug loading. Moreover, the NDDSs were stable during storage and in fetal bovine serum for extended periods, showed low complement consumption and were non-toxic to EAhy926 cells up to high concentrations. Therefore, they can be considered as potential injectable nanocarriers of AG. Due to less pronounced burst effect and extended release characteristics, the nanocapsules could be favorable approaches for achieving prolonged pharmacological activity of AG using injectable NDDS.

Rational design of polyarginine nanocapsules intended to help peptides overcoming intestinal barriers

The aim of this work was to rationally design and characterize nanocapsules (NCs) composed of an oily core and a polyarginine (PARG) shell, intended for oral peptide delivery. The cationic polyaminoacid, PARG, and the oily core components were selected based on their penetration enhancing properties. Insulin was adopted as a model peptide to assess the performance of the NCs. After screening numerous formulation variables, including different oils and surfactants, we defined a composition consisting of oleic acid, sodium deoxycholate (SDC) and Span 80. This selected NCs composition, produced by the solvent displacement technique, exhibited the following key features: (i) an average size of 180nm and a low polydispersity (0.1), (ii) a high insulin association efficacy (80-90% AE), (iii) a good colloidal stability upon incubation in simulated intestinal fluids (SIF, FaSSIF-V2, FeSSIF-V2), and (iv) the capacity to control the release of the associated insulin for >4h. Furthermore, using the Caco-2 model cell line, PARG nanocapsules were able to interact with the enterocytes, and reversibly modify the TEER of the monolayer. Both cell adhesion and membrane permeabilization could account for the pronounced transport of the NCs-associated insulin (3.54%). This improved interaction was also visualized by confocal fluorescent microscopy following oral administration of PARG nanocapsulesto mice. Finally, in vivo efficacy studies performed in normoglycemic rats showed a significant decrease in their plasma glucose levels after treatment. In conclusion, here we disclose key formulation elements for making possible the oral administration of peptides.

Lipid-based nanocarriers for oral peptide delivery

This article is aimed to overview the lipid-based nanostructures designed so far for the oral administration of peptides and proteins, and to analyze the influence of their composition and physicochemical (particle size, zeta potential) and pharmaceutical (drug loading and release) properties, on their interaction with the gastro-intestinal environment, and the subsequent PK/PD profile of the associated drugs. The ultimate goal has been to highlight and comparatively analyze the key factors that may be determinant of the success of these nanocarriers for oral peptide delivery. The article ends with some prospects on the challenges to be addressed for the intended commercial success of these delivery vehicles.

Nanocapsules for 5-fluorouracil delivery decorated with a poly(2-ethylhexyl methacrylate-co-7-(4-trifluoromethyl)coumarin acrylamide) cross-linked wall

Nanocapsules with reverse cross-linked polymer walls containing coumarin moieties are capable of encapsulating 5-fluorouracil and accomplishing a comprehensive strategy in a drug delivery system.

Long-term delivery of protein therapeutics

INTRODUCTION

Proteins are effective biotherapeutics with applications in diverse ailments. Despite being specific and potent, their full clinical potential has not yet been realized. This can be attributed to short half-lives, complex structures, poor in vivo stability, low permeability, frequent parenteral administrations and poor adherence to treatment in chronic diseases. A sustained release system, providing controlled release of proteins, may overcome many of these limitations.

AREAS COVERED

This review focuses on recent development in approaches, especially polymer-based formulations, which can provide therapeutic levels of proteins over extended periods. Advances in particulate, gel-based formulations and novel approaches for extended protein delivery are discussed. Emphasis is placed on dosage form, method of preparation, mechanism of release and stability of biotherapeutics.

EXPERT OPINION

Substantial advancements have been made in the field of extended protein delivery via various polymer-based formulations over last decade despite the unique delivery-related challenges posed by protein biologics. A number of injectable sustained-release formulations have reached market. However, therapeutic application of proteins is still hampered by delivery-related issues. A large number of protein molecules are under clinical trials, and hence, there is an urgent need to develop new methods to deliver these highly potent biologics.

Preparação de nanopartículas poliméricas a partir da polimerização de monômeros: parte I

Nanopartículas poliméricas produzidas a partir de polímeros sintéticos, como copolímeros do ácido metacrílico, ésteres acrílicos ou metacrílicos, têm sido amplamente utilizadas na área farmacêutica para encapsulação de princípios ativos. Essas nanopartículas apresentam as vantagens de proteção, liberação controlada, melhor biodisponibilidade e menor toxicidade, proporcionando maior conforto aos pacientes e adesão ao tratamento. A produção das nanopartículas (nanocápsulas e nanosferas) por polimerização de monômeros é revisada e descrita 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.

New approach to hydrophobic cyanine-type photosensitizer delivery using polymeric oil-cored nanocarriers: hemolytic activity, in vitro cytotoxicity and localization in cancer cells

We report on encapsulation of cyanine IR-768 in oil-in-water (o/w) microemulsion, i.e. fabrication of templated polymeric nanocapsules as effective nanocarriers for a new generation of photodynamic agents suitable for photodynamic therapy (PDT). Discussed here are nanocapsule imaging, their in vitro biological evaluation, cyanine encapsulation potential, and the cellular localization of cyanine IR-768 delivered in the nanocapsules to MCF-7 cancer cells. Oil-cored poly(n-butyl cyanoacrylate) (PBCA) nanocapsules were prepared by interfacial polymerization in o/w microemulsions formed by the nonionics Tween 80 (polysorbate 80, polyoxyethylene 20 sorbitan monooleate), and Brij 96 (polyoxyethylene 10 oleyl ether). Iso-propyl myristate (IPM), ethyl oleate (EOl), iso-octane (IO), and oleic acid (OA) were used as the oil phases and iso-propanol (IP) and propylene glycol (PG) as the cosurfactants. Such o/w droplets, also containing hydrophobic IR-768 in the oil phase, were applied in the interfacial polymerization of n-butyl cyanoacrylate at 10 degrees C at pH 5.0. The isolated cyanine-loaded nanoparticles were visualized by atomic force microscopy (AFM) and scanning electron microscopy (SEM), which proved their unimodal size distribution and spherical shape, with diameters dependent upon the monomer content and the template type. The entrapment efficiency of cyanine increased with increasing n-butyl cyanoacrylate concentration and varied from 65.7% to 91.7%. The results of in vitro erythrocyte hemolysis and the cell viability of breast cancer MCF-7 cells showed that the PBCA nanocapsules are quite safe carriers of IR-768 in the circulation, having a very low hemolytic potential and being non-toxic to the studied cells. Fluorescence microscopy visualized the cyanine intracellular distribution and, furthermore, demonstrated that PBCA-nanocarriers effectively delivered the IR-768 molecules to the MCF-7 doxorubicin-sensitive and -resistant cell lines. Photoirradiation of the cancer cells with entrapped photosensitizer decreased cell viability, demonstrating that this effect may be utilized in PDT.

Oral insulin delivery using nanoparticles based on microemulsions with different structure-types: optimisation and in vivo evaluation

The purpose of this study was to optimise entrapment of insulin in poly(alkylcyanoacrylate) nanoparticles prepared from microemulsions with different microstructure containing isopropyl myristate, caprylocaproyl macrogolglycerides, polyglyceryl oleate and insulin solution and to investigate the in vitro release and bioactivity of insulin in nanoparticles dispersed in the microemulsion templates. Entrapment efficiency and release of insulin were studied using a reverse-phase HPLC assay. Morphology of the nanoparticles was examined with scanning electron microscopy. Bioactivity of insulin was studied using a streptozotocin-diabetic rat model. Nanoparticles were spherical with 200-400 nm in size without significant difference between different microemulsion templates, types and amounts of monomer. Entrapment efficiency increased significantly with increasing monomer concentration but decreased with increasing aqueous fraction in the microemulsion template. Insulin loading however, showed an opposite trend. In vitro release profiles of insulin from the nanoparticles dispersed in the microemulsion templates were controlled by the monomer concentration only. In vivo, a consistent and significant hypoglycemic effect over controls was found for up to 36 h depending on the type of monomer. No significant serum insulin levels were detectable. This study showed that the strategy of delivering insulin orally, entrapped in nanoparticles and dispersed in a biocompatible microemulsion is promising and highlights the importance of optimisation studies in combination with in vivo experiments.

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.

Effect of drug physicochemical properties onin vitrocharacteristics of amphiphilic cyclodextrin nanospheres and nanocapsules

Nanospheres and nanocapsules of an amphiphilic beta-cyclodextrin, beta-CDC6, were evaluated using a group of steroid drugs to determine the effect of drug physicochemical properties (e.g. partition coefficient, drug:CD association constant k1:1, aqueous solubility) on loading and release profiles of the nanoparticles. Model drugs used were hydrocortisone, testosterone and progesterone. Inclusion complexes were formed between model drugs and beta-CDC6 by the co-lyophilization technique and were characterized by DSC analysis and FTIR spectroscopy. Nanospheres and nanocapsules were prepared directly from these inclusion complexes and alternatively by the conventional preparation technique. It was observed that loading depended highly on the technique used. For nanospheres, drug characteristics played a significant role while for nanocapsules this factor had no significant effect on loading values. Release of drugs from nanospheres was completed in 2h, regardless of drug physicochemical properties with high-loading technique. On the other hand, drug release from nanocapsules was largely dependent on drug properties. Only 30% of progesterone was released in 24h, while hydrocortisone was completely released in 8h. Thus, drug properties are significant for the formulation of nanocapsules and nanospheres. Desired loading and release properties could be achieved by selecting the appropriate drug delivery system and the optimum drug.

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.

Characterisation of colloidal drug delivery systems from the naked eye to Cryo-FESEM

Poly(ethylcyanoacrylate) nanoparticles prepared by interfacial polymerisation on the basis of microemulsions were prepared in this study and both colloidal systems, nanoparticles and microemulsions, were analysed by visual observation and several microscopic techniques. Phase boundaries for the microemulsions of the two pseudoternary systems ethyloleate, polyoxyethylene 20 sorbitan mono-oleate/sorbitan monolaurate and water with and without butanol as a cosurfactant were determined by visual observation of the samples. Microemulsions containing liquid crystals were determined by polarisation light microscopy. Using freeze-fracture transmission electron microscopy and Cryo-field emission scanning electron microscopy the type of microemulsion (w/o droplet, bicontinuous, solution) was characterised. Nanoparticles prepared from the different types of microemulsion were additionally observed by conventional scanning electron microscopy. The size of the nanoparticles obtained from electron microscopy was in good agreement with particle sizing techniques (photon correlation spectroscopy) from earlier studies and no morphological differences could be observed in particles prepared from the different types of microemulsions. Cryo-field emission scanning electron microscopy proved to be a most valuable technique in the visualisation of the colloidal systems as samples could be observed close to their natural state.

Application of pharmaceutical drug delivery for biological control of the common brushtail possum in New Zealand: a review

The common brushtail possum (Trichosurus vulpecula) is the most significant vertebrate pest in New Zealand, being a major ecological threat to the indigenous biodiversity and an economic threat as a vector for bovine tuberculosis. Novel and effective strategies to reduce the population of T. vulpecula are needed urgently. Several biocontrol agents are currently being assessed and from research to date it is likely that the biocontrol agents will be peptide or protein molecules. It is not possible to administer such biocontrol agents alone because they would be degraded rapidly in the animal, especially if delivered orally. Technologies used in the pharmaceutical industry to design efficacious drug-delivery systems for humans and animals can be applied to the design of delivery systems for biocontrol agents used in wildlife management, although there are some unique challenges that must be overcome.

Using different structure types of microemulsions for the preparation of poly(alkylcyanoacrylate) nanoparticles by interfacial polymerization

A phase diagram of the pseudoternary system ethyloleate, polyoxyethylene 20 sorbitan mono-oleate/sorbitan monolaurate and water with butanol as a cosurfactant was prepared. Areas containing optically isotropic, low viscosity one-phase systems were identified and systems therein designated as w/o droplet-, bicontinuous- or solution-type microemulsions using conductivity, viscosity, cryo-field emission scanning electron microscopy and self-diffusion NMR. Nanoparticles were prepared by interfacial polymerization of selected w/o droplet, bicontinuous- or solution-type microemulsions with ethyl-2-cyanoacrylate. Morphology of the particles and entrapment of the water-soluble model protein ovalbumin were investigated. Addition of monomer to the different types of microemulsions (w/o droplet, bicontinuous, solution) led to the formation of nanoparticles, which were similar in size ( approximately 250 nm), polydispersity index ( approximately 0.13), zeta-potential ( approximately -17 mV) and morphology. The entrapment of the protein within these particles was up to 95%, depending on the amount of monomer used for polymerization and the type of microemulsion used as a polymerization template. The formation of particles with similar characteristics from templates having different microstructure is surprising, particularly considering that polymerization is expected to occur at the water-oil interface by base-catalysed polymerization. Dynamics within the template (stirring, viscosity) or indeed interfacial phenomena relating to the solid-liquid interface appear to be more important for the determination of nanoparticle morphology and characteristics than the microstructure of the template system.

Polymeric particulates to improve oral bioavailability of peptide drugs

Oral administration remains the most convenient way of delivering drugs. Recent advances in biotechnology have produced highly potent new molecules such as peptides, proteins and nucleic acids. Due to their sensitivity to chemical and enzymatic hydrolysis as well as a poor cellular uptake, their oral bioavailability remains very low. Despite sophisticated new delivery systems, the development of a satisfactory oral formulation remains a challenge. Among the possible strategies to improve the absorption of drugs, micro- and nanoparticles represent an exciting approach to enhance the uptake and transport of orally administered molecules. Increasing attention has been paid to their potential use as carriers for peptide drugs for oral administration.

This article reviews the most common manufacturing methods for polymeric particles and the physiology of particle absorption from the gastrointestinal (GI) tract. In a second part, the use of polymeric particulate systems to improve the oral absorption of insulin is discussed.

Nanosuspensions: a promising drug delivery strategy

Nanosuspensions have emerged as a promising strategy for the efficient delivery of hydrophobic drugs because of their versatile features and unique advantages. Techniques such as media milling and high-pressure homogenization have been used commercially for producing nanosuspensions. Recently, the engineering of nanosuspensions employing emulsions and microemulsions as templates has been addressed in the literature. The unique features of nanosuspensions have enabled their use in various dosage forms, including specialized delivery systems such as mucoadhesive hydrogels. Rapid strides have been made in the delivery of nanosuspensions by parenteral, peroral, ocular and pulmonary routes. Currently, efforts are being directed to extending their applications in site-specific drug delivery.