Nanoencapsulation I. Methods for preparation of drug-loaded polymeric nanoparticles

Nanomaterials: applications in cancer imaging and therapy

The application of nanomaterials (NMs) in biomedicine is increasing rapidly and offers excellent prospects for the development of new non-invasive strategies for the diagnosis and treatment of cancer. In this review, we provide a brief description of cancer pathology and the characteristics that are important for tumor-targeted NM design, followed by an overview of the different types of NMs explored to date, covering synthetic aspects and approaches explored for their application in unimodal and multimodal imaging, diagnosis and therapy. Significant synthetic advances now allow for the preparation of NMs with highly controlled geometry, surface charge, physicochemical properties, and the decoration of their surfaces with polymers and bioactive molecules in order to improve biocompatibility and to achieve active targeting. This is stimulating the development of a diverse range of nanometer-sized objects that can recognize cancer tissue, enabling visualization of tumors, delivery of anti-cancer drugs and/or the destruction of tumors by different therapeutic techniques.

Systemic and mucosal delivery of drugs within polymeric microparticles produced by spray drying

Encapsulation of therapeutic and diagnostic materials into polymeric particles is a means to protect and control or target the release of active substances such as drugs, vaccines, and genetic material. In terms of mucosal delivery, polymeric encapsulation can be used to promote absorption of the active substance, while particles can improve the half-life of drugs administered systemically. Spray drying is an attractive technology used to produce such microparticles, because it combines both the encapsulation and drying steps in a rapid, single-step operation. Even so, spray drying is not classically associated with processes used for drug and therapeutic material encapsulation, since elevated temperatures could potentially denature the active substance. However, a comprehensive review of the literature revealed a number of studies demonstrating that spray drying can be used to produce microparticulate formulations with labile therapeutics. Polymers commonly employed include synthetics such as methacrylic copolymers and polyesters, and natural materials including chitosan and alginate. Drugs and active substances are diverse and included antibiotics, anti-inflammatory agents, and chemotherapeutics. Regarding the delivery of spray-dried particles, the pulmonary, oral, colonic, and nasal mucosal routes are often investigated because they offer a convenient means of administration, which promotes physician and patient compliance. In addition, spray drying has been widely used to produce polymeric microparticles for systemic delivery in order to control the delivery of drugs, vaccines, or genetic material that may exhibit poor pharmacokinetic profiles or pose toxicity concerns. This review presents a brief introduction to the technology of spray drying and outlines the delivery routes and the applications of spray-dried polymeric microparticles.

A Novel Aerosol Method for the Production of Hydrogel Particles

A novel method of generating hydrogel particles for various applications including drug delivery purposes was developed. This method is based on the production of hydrogel particles from sprayed polymeric nano/microdroplets obtained by a nebulization process that is immediately followed by gelation in a crosslinking fluid. In this study, particle synthesis parameters such as type of nebulizer, type of crosslinker, air pressure, and polymer concentration were investigated for their impact on the mean particle size, swelling behavior, and morphology of the developed particles. Spherical alginate-based hydrogel particles with a mean particle size in the range from 842 to 886 nm were obtained. Using statistical analysis of the factorial design of experiment it was found that the main factors influencing the size and swelling values of the particles are the alginate concentration and the air pressure. Thus, it was demonstrated that the method described in the current study is promising for the generation of hydrogel particles and it constitutes a relatively simple and low-cost system.

Small-molecule delivery by nanoparticles for anticancer therapy

Using nanoparticles for the delivery of small molecules in anticancer therapy is a rapidly growing area of research. The advantages of using nanoparticles for drug delivery include enhanced water solubility, tumor-specific accumulation and improved antitumor efficacy, while reducing nonspecific toxicity. Current research in this field focuses on understanding precisely how small molecules are released from nanoparticles and delivered to the targeted tumor tissues or cells, and how the unique biodistribution of the drug-carrying nanoparticles limits toxicity in major organs. Here, we discuss existing nanoparticles for the delivery of small-molecule anticancer agents and recent advances in this field.

Chitosan nanocapsules: Effect of chitosan molecular weight and acetylation degree on electrokinetic behaviour and colloidal stability

In recent years, chitosan nanocapsules have shown promising results as carriers for oral drug or peptide delivery. The success in their applicability strongly depends on the stability of these colloidal systems passing through the digestive tract. In gastric fluids, clear stability comes from the high surface charge density of the chitosan shell, which is completely charged at acidic pH values. However, in the intestinal fluid (where the pH is almost neutral) the effective charge of these nanocapsules approaches zero, and the electrostatic forces cannot provide any stabilization. Despite the lack of surface charge, chitosan nanocapsules remain stable in simulated intestinal fluids. Recently, we have demonstrated that this anomalous stability (at zero charge) is owed to short-range repulsive forces that appear between hydrophilic particles when immersed in saline media. The present work examines the influence of the chitosan hydrophobicity, as well as molecular weight, in the stability of different chitosan nanocapsules. A study has been made of the size, polydispersity, electrophoretic mobility, and colloidal stability of eight core-shell nanocapsule systems, in which the chitosan-shell properties have been modified using low-molecular-weight (LMW) and high-molecular-weight (HMW) chitosan chains having different degrees of acetylation (DA). With regard to the stability mediated by repulsive hydration forces, the LMW chitosan provided the best results. In addition, contrary to initial expectations, greater stability (also mediated by hydration forces) was found in the samples formed with chitosan chains of high DA values (i.e. with less hydrophilic chitosan). Finally, a theoretical treatment was also tested to quantify the hydrophilicity of the chitosan shells.

Superparamagnetic iron oxide--loaded poly(lactic acid)-D-alpha-tocopherol polyethylene glycol 1000 succinate copolymer nanoparticles as MRI contrast agent

We developed a strategy to formulate supraparamagnetic iron oxides (SPIOs) in nanoparticles (NPs) of biodegradable copolymer made up of poly(lactic acid) (PLA) and d-alpha-tocopherol polyethylene glycol 1000 succinate (TPGS) for medical imaging by magnetic resonance imaging (MRI) of high contrast and low side effects. The IOs-loaded PLA-TPGS NPs (IOs-PNPs) were prepared by the single emulsion method and the nanoprecipitation method. Effects of the process parameters such as the emulsifier concentration, IOs loading in the nanoparticles, and the solvent to non-solvent ratio on the IOs distribution within the polymeric matrix were investigated and the formulation was then optimized. The transmission electron microscopy (TEM) showed direct visual evidence for the well dispersed distribution of the IOs within the NPs. We further investigated the biocompatibility and cellular uptake of the IOs-PNPs in vitro with MCF-7 breast cancer cells and NIH-3T3 mouse fibroblast in close comparison with the commercial IOs imaging agent Resovist. MRI imaging was further carried out to investigate the biodistribution of the IOs formulated in the IOs-PNPs, especially in the liver to understand the liver clearance process, which was also made in close comparison with Resovist. We found that the PLA-TPGS NPs formulation at the clinically approved dose of 0.8 mg Fe/kg could be cleared within 24 h in comparison with several weeks for Resovist. Xenograft tumor model MRI confirmed the advantages of the IOs-PNPs formulation versus Resovist through the enhanced permeation and retention (EPR) effect of the tumor vasculature.

Folate targeted polymeric 'green' nanotherapy for cancer

The concept of 'green' chemotherapy by employing targeted nanoparticle mediated delivery to enhance the efficacy of phytomedicines is reported. Poly (lactide-co-glycolide) (PLGA) nanoparticles encapsulating a well known nutraceutical namely, grape seed extract (GSE)-'NanoGSE'-was prepared by a nanoprecipitation technique. The drug-loaded nanoparticles of size approximately 100 nm exhibited high colloidal stability at physiological pH. Molecular receptor targeting of this nanophytomedicine against folate receptor over-expressing cancers was demonstrated in vitro by conjugation with a potential cancer targeting ligand, folic acid (FA). Fluorescence microscopy and flow cytometry data showed highly specific cellular uptake of FA conjugated NanoGSE on folate receptor positive cancer cells. Studies were also conducted to investigate the efficiency of targeted (FA conjugated) versus non-targeted (non-FA conjugated) nanoformulations in causing cancer cell death. The IC(50) values were lowered by a factor of approximately 3 for FA-NanoGSE compared to the free drug, indicating substantially enhanced bioavailability to the tumor cells, sparing the normal ones. Receptor targeting of FA-NanoGSE resulted in a significant increase in apoptotic index, which was also quantified by flow cytometry and fluorescence microscopy. This in vitro study provides a basis for the use of nanoparticle mediated delivery of anticancer nutraceuticals to enhance bioavailability and effectively target cancer by a 'green' approach.

Nanoencapsulation method for high selectivity sensing of hydrogen peroxide inside live cells

Reactive oxygen species (ROS) are ubiquitous in life and death processes of cells (Finkel, T.; Holbrook, N. J. Nature 2000, 408 (6809), 239-247), with a major role played by the most stable ROS, hydrogen peroxide (H(2)O(2)). However, the study of H(2)O(2) in live cells has been hampered by the absence of selective probes. Described here is a novel nanoprobe ("nanoPEBBLE") with dramatically improved H(2)O(2) selectivity. The traditional molecular probe, 2',7'-dichlorofluorescin (DCFH), which is also sensitive to most other ROS, was empowered with high selectivity by a nanomatrix that blocks the interference from all other ROS (hydroxyl radical, superoxide, nitric oxide, peroxynitrite, hypochlorous acid, and alkylperoxyl radical), as well as from enzymes such as peroxidases. The blocking is based on the combination of multiple exclusion principles: time barrier, hydrophobic energy barrier, and size barrier. However, H(2)O(2) sensitivity is maintained down to low nanomolar concentrations. The surface of the nanoprobe was engineered to address biological applications, and the power of this new nanoPEBBLE is demonstrated by its use on RAW264.7 murine macrophages. These nanoprobes may provide a powerful chemical detection/imaging tool for investigating biological mechanisms related to H(2)O(2) or other species, with high spatial and temporal resolution.

Drug delivery systems: Advanced technologies potentially applicable in personalized treatments

Advanced drug delivery systems (DDS) present indubitable benefits for drug administration. Over the past three decades, new approaches have been suggested for the development of novel carriers for drug delivery. In this review, we describe general concepts and emerging research in this field based on multidisciplinary approaches aimed at creating personalized treatment for a broad range of highly prevalent diseases (e.g., cancer and diabetes). This review is composed of two parts. The first part provides an overview on currently available drug delivery technologies including a brief history on the development of these systems and some of the research strategies applied. The second part provides information about the most advanced drug delivery devices using stimuli-responsive polymers. Their synthesis using controlled-living radical polymerization strategy is described. In a near future it is predictable the appearance of new effective tailor-made DDS, resulting from knowledge of different interdisciplinary sciences, in a perspective of creating personalized medical solutions.

Preparation, physicochemical characterization and cytotoxicity in vitro of gemcitabine-loaded PEG-PDLLA nanovesicles

AIM: To investigate the preparation, physicochemical characterization and cytotoxicity in vitro of Gemcitabine-loaded poly(ethylene glycol)-block-poly(D,L-lactide) (PEG-PDLLA) nanovesicles.

METHODS: The nanovesicle carriers were prepared from the amphiphilic block copolymer of PEG-PDLLA by a double emulsion technique, and gemcitabine was used as the model drug. The morphology of the nanovesicles was determined by scanning and transmission electron microscopy, and the drug content, drug entrapment and drug-release curve in vitro were detected by UV-Vis-NIR spectrophotometry. Cytotoxicity in the human pancreatic cancer cell line SW1990 was tested by 3-(4,5-dimethyl) ethiazole (MTT) assay.

RESULTS: The gemcitabine-loaded nanovesicles were hollow nanospheres with a mean size of 200.6 nm, drug loading of 4.14% and drug embedding ratio of 20.54%. The nanovesicles showed excellent controlled release that was characterized by a fast initial release during the first 72 h, followed by a slower and continuous release. The MTT assay demonstrated that gemcitabine-loaded nanovesicles exhibited dose-dependent and time-delayed cytotoxicity in the human pancreatic cancer cell line SW1990.

CONCLUSION: Gemcitabine-loaded PEG-PDLLA nanovesicles prepared by a double emulsion technique exhibited good performance for controlled drug release, and had similar cytotoxic activity to free gemcitabine.

Self-assembled particles of N-phthaloylchitosan-g-polycaprolactone molecular bottle brushes as carriers for controlled release of indometacin

A series of amphiphilic N-phthaloylchitosan-g-polycaprolactone molecular bottle brushes were prepared by "graft onto" method. The narrow distribution of polycaprolactone macromonomers ensures that the molecular bottle brushes can self-assemble into highly monodisperse particles, which have the ability to get a high loading efficiency of the hydrophobic drug, indometacin (INN). Searching for the effective drug loading ratio, three parameters such as polycaprolactone chain length, the grafting content and concentration of the molecular bottle brushes were tested to entrap INN. These encapsulated drug particles show sustained release of the encapsulated INN, of which 91.7% was released in 22 h at 37 degrees C in phosphate buffered saline. The self-assembled particles of the molecular bottle brushes as carriers for INN can effectively prevent the drug from releasing quickly and prolong the release time, which is a promising candidate for potential clinical applications.

Biodegradable polymeric nanoparticles based drug delivery systems

Biodegradable nanoparticles have been used frequently as drug delivery vehicles due to its grand bioavailability, better encapsulation, control release and less toxic properties. Various nanoparticulate systems, general synthesis and encapsulation process, control release and improvement of therapeutic value of nanoencapsulated drugs are covered in this review. We have highlighted the impact of nanoencapsulation of various disease related drugs on biodegradable nanoparticles such as PLGA, PLA, chitosan, gelatin, polycaprolactone and poly-alkyl-cyanoacrylates.

Preparation of drug-loaded polymeric nanoparticles and evaluation of the antioxidant activity against lipid peroxidation

Antioxidants have been found to be effective as prophylatic and therapeutic agents for different diseases such as diabetes, cancer, and neurodegenerative disorders. However, antioxidant substances can present poor solubility in water, inefficient permeability, gastrointestinal degradation, first-pass effect, and/or instability during storage. These drawbacks can be potentially circumvented by encapsulating the susceptible antioxidants. Polymeric nanoparticles (nanocapsules or nanospheres) have been used to improve the drug efficacy and release. Our group has shown that the in vitro antioxidant effect of melatonin against lipid peroxidation in microsomes and liposomes can be improved by encapsulation of the antioxidant drug in polymeric nanoparticles.

Preparation, characterization, in vivo and in vitro studies of arsenic trioxide Mg-Fe ferrite magnetic nanoparticles

AIM

MgFe(2)O(4) magnetic nanoparticle composed of As(2)O(3) (As(2)O(3)-MNPs) were prepared and their in vitro and in vivo characteristics were studied.

METHODS

The solvent-displacement method was applied for preparation of the nanoparticle using Poly-D,L-lactic-co-glycolic acid(PLGA). The characteristics studies of the products included magnetic response, morphology (transmission electron microscopy and scanning electron microscopy), entrapment efficiency, drug loading, particle sizes, zeta potential, in vitro drug release and tissue magnetic targeting. Nanoparticle cytotoxicity to Saos-2 cells was investigated using the MTT assay. To guide the external magnetic field in the liver, the concentration of As(2)O(3) in the liver and kidney was measured using an atomic fluorescence spectrometer after injecting As(2)O(3)-MNPs into the caudal veins of mice.

RESULTS

The As(2)O(3)-MNPs were approximately spherical. The average diameter, drug loading, entrapment efficiency and zeta potential of As(2)O(3)-MNPs were 109.9 nm, 10.08%, 82.16%, and -14.33 mV, respectively. The specific saturation magnetism was 8.65 emu/g. In vivo, the concentration of As(2)O(3) in the liver was significantly higher than that in the non-magnetic group. While the concentration of As(2)O(3) in the kidney was lower than that in the non-magnetic group. The C(max) in liver tissue in the magnetic group was 30.65 microg/g, which was 4.17 times the drug concentration in the same group in kidney tissue (7.35 microg/g) and 2.88 times the concentration of drug (10.66 microg/g) in the liver tissue of the non-magnetic group.

CONCLUSION

The PLGA polymer-loaded magnetic nanoparticle composed of arsenic trioxide can be magnetically targeted well and applied in biomedicine.

Self-assembled nanoparticle drug delivery systems from galactosylated polysaccharide-doxorubicin conjugate loaded doxorubicin

Xyloglucan was grafted with the doxorubicin (DOX) and galactosamine, a terminal moiety that can be used to target polymeric conjugates to liver hepatocytes. The content of the DOX was over 5% (wt) in the conjugate. The polymeric drug assisted to form nanoparticle drug delivery systems (nanoDDSs) with an average size of 142 nm in diameter when combined with an excess amount of deprotonated doxorubicin in an aqueous phase. A loading content of doxorubicin is as high as 23.8% in the nanoDDS. In an in vitro cytotoxicity experiment, the novel nanoDDS has similar cytotoxicity as free DOX against HepG2 cells. In contrast, for the incubation with HeLa cells of the novel nanoDDS, there was no significant cytotoxicity change. In a human tumor xenograft nude mouse model, the novel nanoDDS generated higher therapeutic effect than non-targeted doxorubicin nanoparticles or free doxorubicin. Together, these results suggest that novel nanoDDS, which has improved transfection efficiency and hepatocyte specificity, may be useful for tumor therapy.

The preparation of size-controlled functionalized polymeric nanoparticles in micelles

The reverse micellar system of dioctyl-sulfosuccinate (AOT)/octane and toluene have been used as a template for polymerization of acrylamide (AA)/bisacrylamide (BAA)-based functionalized polymeric nanoparticles. Such nanoparticles are typically sized between 20 and 90 nm. They can be synthesized with different functional groups according to the monomers added to the polymerization mixture. In our experiments the nanoparticles carried amino and carboxyl groups following incorporation of allylamine (AAm) or methacrylic acid (MAA) monomers, respectively. The available amine or carboxyl groups can then be used for immobilization of enzymes or other biomolecules. These enzymes, subtilisin, laccase and lipase, were immobilized onto polyAA/BAA/MAA nanoparticles covalently after activating the MAA carboxylic groups with Woodward's K reagent. Non-covalent immobilization via electrostatic interaction was also performed.

Novel biodegradable polyesters. Synthesis and application as drug carriers for the preparation of raloxifene HCl loaded nanoparticles

Raloxifene HCl is a drug with poor bioavailability and poor water solubility. Furthermore nο pharmaceutically acceptable organic solvent has been reported before to dilute the drug. It was observed that Raloxifene HCl can be diluted in a solvent mixture of acetone/water or ethanol/water. The aim of this study was to use biodegradable polymers in order to prepare Raloxifene HCl nanoparticles. For this purpose a series of novel biodegradable poly(ethylene succinate-co-propylene adipate) P(ESu-co-PAd) polyesters were synthesized following the polycondensation method and further, poly(ethylene succinate) (PESu) and poly(propylene adipate) (PPAd) were used. The prepared polyesters were characterized by intrinsic viscosity measurements, end group analysis, enzymatic hydrolysis, Nuclear Magnetic Resonance Spectroscopy (^1Η-NMR and ¹³C-NMR) and Wide-angle X-ray Diffractometry (WAXD). The drug nanoparticles have been prepared by a variation of the co-precipitation method and were studied by Wide-angle X-ray Diffractometry (WAXD), FTIR spectrometry, light scattering size distribution, Scanning Electron Microscopy (SEM) and release behavior measurements. The interactions between the polymers and the drug seem to be limited, so the drug occurs in crystalline form in all nanoparticles. The size of the nanoparticles seems to be in the range of 150-350 nm, depending on the polymer that was used. The drug release depends on the melting point and degree of crystallinity of the polyesters used. An initial high release rate was recorded followed by very slow rates of controlled release.

PLGA nanoparticle formulations of risperidone: preparation and neuropharmacological evaluation

The aim of this work was to develop extended-release poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles of risperidone and thermal-responsive in situ gel containing risperidone nanoparticles for parenteral (subcutaneous) delivery and to reduce the dose-dependent extrapyramidal side effects of risperidone. PLGA nanoparticles of risperidone were designed by nanoprecipitation method using polymeric stabilizer (Poloxamer 407). The prepared nanoparticles were characterized for particle size by photon correlation spectroscopy and atomic force microscopy. Poloxamer 407-based in situ gel containing PLGA nanoparticles of risperidone was prepared by modified cold method to control the initial rapid release from the nanoparticles. The in vivo efficacy (antipsychotic effect) of prepared formulations (nanoparticles and in situ gel containing nanoparticles) was studied by administering them subcutaneously to mice. Extrapyramidal side effects of the formulations were also studied. The particle size of the prepared nanoparticles ranged between 85 and 219 nm. About 89% to 95% drug encapsulation efficiency was achieved when risperidone was loaded at 1.7% to 8.3% by weight of the polymer. During in vivo studies prepared risperidone formulations showed an antipsychotic effect that was significantly prolonged over that of risperidone solution for up to 72 hours with fewer extrapyramidal side effects. The prolonged effect of risperidone was obtained from the risperidone formulations administered subcutaneously, and this may improve the treatment of psychotic disorders by dose reduction.

FROM THE CLINICAL EDITOR

The development of extended-release poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles of risperidone is reported in this paper, along with the development of thermal-responsive in situ gel containing risperidone nanoparticles for parenteral (subcutaneous) delivery and to reduce the dose-dependent extrapyramidal side effects. In vivo studies showed a significantly prolonged antipsychotic effect with fewer extrapyramidal side effects.

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.

Polysaccharides-based nanoparticles as drug delivery systems

Natural polysaccharides, due to their outstanding merits, have received more and more attention in the field of drug delivery systems. In particular, polysaccharides seem to be the most promising materials in the preparation of nanometeric carriers. This review relates to the newest developments in the preparation of polysaccharides-based nanoparticles. In this review, four mechanisms are introduced to prepare polysaccharides-based nanoparticles, that is, covalent crosslinking, ionic crosslinking, polyelectrolyte complex, and the self-assembly of hydrophobically modified polysaccharides.

Preparation of polyurethane nanocapsules by miniemulsion polyaddition

The encapsulation of organic liquids in polyurethane nanocapsules by interfacial miniemulsion polycondensation of isophorone diisocyanate and propanetriol has been performed. The influence of type and amount of encapsulated organic liquid has been studied and it was found that the encapsulation efficiency is dependent on the water solubility of the organic liquids, their interfacial tension against water and their compatibility with polyurethane. It was also shown how different types of surfactants and variations in pH and ionic strength of the continuous phase affected the stability during polymerization and the diameter of the miniemulsion droplets and the resulting nanocapsules. The long-chained anionic surfactant Disponil FES77 can be utilized over a larger pH range than SDS due to the contribution of steric stabilization. Relatively narrow size distributions were obtained.

Nanovehicular intracellular delivery systems

This article provides an overview of principles and barriers relevant to intracellular drug and gene transport, accumulation and retention (collectively called as drug delivery) by means of nanovehicles (NV). The aim is to deliver a cargo to a particular intracellular site, if possible, to exert a local action. Some of the principles discussed in this article apply to noncolloidal drugs that are not permeable to the plasma membrane or to the blood-brain barrier. NV are defined as a wide range of nanosized particles leading to colloidal objects which are capable of entering cells and tissues and delivering a cargo intracelullarly. Different localization and targeting means are discussed. Limited discussion on pharmacokinetics and pharmacodynamics is also presented. NVs are contrasted to micro-delivery and current nanotechnologies which are already in commercial use. Newer developments in NV technologies are outlined and future applications are stressed. We also briefly review the existing modeling tools and approaches to quantitatively describe the behavior of targeted NV within the vascular and tumor compartments, an area of particular importance. While we list "elementary" phenomena related to different level of complexity of delivery to cancer, we also stress importance of multi-scale modeling and bottom-up systems biology approach.

Studies on biodegradable polymeric nanoparticles of risperidone: in vitro and in vivo evaluation

AIM

The aim of this work was to develop extended-release risperidone nanoparticles for parenteral delivery (intravenous) and to reduce the dose-dependent extrapyramidal side effects of risperidone.

METHODS

Polymeric nanoparticles containing risperidone made of poly (epsilon-caprolactone) were designed by the nanoprecipitation method using polymeric stabilizers (poloxamers). The in vivo efficacy of prepared formulations and the risperidone solution was studied by administering them intravenously to apomorphine-treated mice. Extrapyramidal side effects of the risperidone and its formulations were also studied.

RESULTS

The particle size of the prepared nanoparticles ranged between 99 and 304 nm. Approximately 78-85% drug-encapsulation efficiency was achieved when risperidone was loaded at 1.7-4.1% by weight of the polymer. During in vivo studies, prepared risperidone-containing formulations showed a significant prolonged antipsychotic effect than that of risperidone solution, also having less extrapyramidal side effects.

CONCLUSION

The prolonged effect of risperidone was obtained from the nanoparticles of risperidone administered by the intravenous route and this may improve the treatment of psychotic disorders by dose reduction.

Micro/nanostructured polymeric systems for biomedical and pharmaceutical applications

This review provides an outline of the polymeric micro/nanostructured advanced systems that are suited for the controlled and targeted administration of, specifically, nonconventional drugs. The contribution of new trends in drug-delivery technology is focused on two major parts, dealing with brief surveys of: the biodegradable/bioerodible polymeric systems used in the formulation of micro/nanoparticles and techniques used in the preparation of micro/nanoparticles for their biomedical application in cancer treatment specifically, in inflammation pathologies, as oxygen carriers (blood substitutes) and in tissue-engineering practice. A small discussion of the future perspectives of the described systems is also given.