PLGA nanoparticles containing praziquantel: effect of formulation variables on size distribution

Comparative manufacture and cell-based delivery of antiretroviral nanoformulations

Nanoformulations of crystalline indinavir, ritonavir, atazanavir, and efavirenz were manufactured by wet milling, homogenization or sonication with a variety of excipients. The chemical, biological, immune, virological, and toxicological properties of these formulations were compared using an established monocyte-derived macrophage scoring indicator system. Measurements of drug uptake, retention, release, and antiretroviral activity demonstrated differences amongst preparation methods. Interestingly, for drug cell targeting and antiretroviral responses the most significant difference among the particles was the drug itself. We posit that the choice of drug and formulation composition may ultimately affect clinical utility.

Design of vitamin E d-α-Tocopheryl Polyethylene Glycol 1000 Succinate-Emulsified Poly (D,L-Lactide-co-Glycolide) Nanoparticles: Influence of Duration of Ultrasonication Energy

The aim of this research was to investigate the effect of the duration of ultrasonication energy on the physicochemical characteristics of the nano-sized particulate drug delivery systems. For this purpose, meloxicam-loaded vitamin E d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS)-emulsified poly (D,L-lactide-co-glycolide) (PLGA) nanoparticles were designed by using ultrasonication-solvent evaporation technique and were characterized by photon correlation spectroscopy for size and size distribution, scanning electron microscopy for surface morphology and laser Doppler anemometry for surface charge. Ultraviolet -spectrophotometer was used to measure the drug encapsulation efficiency and to obtain in vitro drug release profile. The results showed that the physicochemical properties of the prepared nanoparticles are effectively controlled by the amount of shear stress transferred from the energy source to the emulsion, which is strongly correlated to the ultrasonication time.

Physicochemical properties and biocompatibility of a polymer-paclitaxel conjugate for cancer treatment

Background

Poly(L-γ-glutamylglutamine) paclitaxel (PGG-PTX) conjugate is a non-diblock polymeric drug nanoparticle intended to improve the therapeutic index of paclitaxel. The purpose of the present study was to elucidate further the physicochemical properties of PGG-PTX in order to proceed with its clinical development.

Methods and results

PGG-PTX was designed by integration of a hydrophobic paclitaxel conjugate through an added hydrophilic glutamic acid onto poly(L-glutamic acid). The addition of a flexible glutamic linker between PGA and paclitaxel resulted in spontaneous self-assembly of a PGG-PTX conjugate into nanoparticles. The PGG-PTX conjugate was stable as a lyophilized solid form. An in vitro viability experiment showed that PGG-PTX was effective after a longer incubation period, the same trend as Taxol. In vitro studies using NCI-H460 and B16F0 cancer cells demonstrated significantly high cellular uptake after 30 minutes of incubation. The in vivo biocompatibility of PGG-PTX conjugate was evaluated in the NCI-H460 tumor model, the assessment of tissue seemed to be normal after 21 days of treatment.

Conclusion

These results are encouraging for further development of non-block polymeric paclitaxel nanoparticles for treatment of cancer.

Practical preparation procedures for docetaxel-loaded nanoparticles using polylactic acid-co-glycolic acid

Background

Nanoparticles fabricated from the biodegradable and biocompatible polymer, polylactic-co-glycolic acid (PLGA), are the most intensively investigated polymers for drug delivery systems. The objective of this study was to explore fully the development of a PLGA nanoparticle drug delivery system for alternative preparation of a commercial formulation. In our nanoparticle fabrication, our purpose was to compare various preparation parameters.

Methods

Docetaxel-loaded PLGA nanoparticles were prepared by a single emulsion technique and solvent evaporation. The nanoparticles were characterized by various techniques, including scanning electron microscopy for surface morphology, dynamic light scattering for size and zeta potential, x-ray photoelectron spectroscopy for surface chemistry, and high-performance liquid chromatography for in vitro drug release kinetics. To obtain a smaller particle, 0.2% polyvinyl alcohol, 0.03% D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), 2% Poloxamer 188, a five-minute sonication time, 130 W sonication power, evaporation with magnetic stirring, and centrifugation at 8000 rpm were selected. To increase encapsulation efficiency in the nanoparticles, certain factors were varied, ie, 2–5 minutes of sonication time, 70–130 W sonication power, and 5–25 mg drug loading.

Results

A five-minute sonication time, 130 W sonication power, and a 10 mg drug loading amount were selected. Under these conditions, the nanoparticles reached over 90% encapsulation efficiency. Release kinetics showed that 20.83%, 40.07%, and 51.5% of the docetaxel was released in 28 days from nanoparticles containing Poloxamer 188, TPGS, or polyvinyl alcohol, respectively. TPGS and Poloxamer 188 had slower release kinetics than polyvinyl alcohol. It was predicted that there was residual drug remaining on the surface from x-ray photoelectron spectroscopy.

Conclusion

Our research shows that the choice of surfactant is important for controlled release of docetaxel.

In vitro release characteristics and cellular uptake of poly(D,L-lactic-co-glycolic acid) nanoparticles for topical delivery of antisense oligodeoxynucleotides

The efficacy of antisense oligodeoxynucleotides (AsODNs) is compromised by their poor stability in biological fluids and the inefficient cellular uptake due to their size and negative charge. Since chemical modifications of these molecules have resulted in a number of non-antisense activities, incorporation into particulate delivery systems has offered a promising alternative. The aim of this study was to evaluate various poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles for AsODN entrapment and delivery. PLGA nanoparticles were prepared using the double emulsion solvent evaporation method. The influence of formulation parameters such as PLGA concentration and volume ratio of internal aqueous phase volume (Va1) to organic phase volume (Vo) to external aqueous phase volume (Va2) on particle size, polydispersity index (PDI) and zeta potential (ZP) was investigated using a full factorial study. The particle size increased with increasing PLGA concentrations and volume ratios, with an interaction detectable between the two factors. AsODN entrapment efficiencies ranged between 49.97% and 54.95% with no significant difference between various formulations. By fitting the in vitro release profiles to a dual first order release model it was shown that the AsODN release occurred via two processes: a diffusion controlled process in the early phase (25 to 32% within one day) and a PLGA degradation process in the latter (39 to 70% after 14 days). Cellular uptake studies using primary corneal epithelial cells suggested active transport of nanoparticles via endocytosis. PLGA nanoparticles therefore show potential to successfully entrap AsODNs, transport them into cells and release them over time due to polymer erosion.

Doxorubicin-loaded (PEG)₃-PLA nanopolymersomes: effect of solvents and process parameters on formulation development and in vitro study

This study is focused on the preparation of doxorubicin-loaded nanopolymersomes (PolyDoxSome) and assessment of the effects of various solvents and process variables on the size and drug loading during preparation of formulation. PolyDoxSome was prepared by nanoprecipitation method using amphiphilic (PEG)₃-PLA copolymer, and the formation of polymersomes was assessed by dynamic light scattering and optical and transmission electron microscopy and evaluated for in vitro release profile and in vitro cytotoxicity. A systematic investigation indicated that solvent composition, order of addition, aqueous phase, copolymer concentration, and external energy input have significant influence on size and dispersity of PolyDoxSome. Under optimized conditions, PolyDoxSome had a size range of 130-180 nm with PDI < 0.2, a zeta potential ∼-8 mV, and a drug loading at ∼11% w/w with an encapsulation efficiency at ∼53% w/w. In vitro release profile of PolyDoxSome at 37 °C demonstrated that doxorubicin release was pH dependent and gave higher release at pH 5.5 in comparison to the release at pH 7.4 (similarity factor, f₂ < 50). PolyDoxSome exhibited enhanced cellular uptake of doxorubicin compared to free doxorubicin solution in MCF-7 cell line and showed a better cytotoxicity of doxorubicin at equivalent dose in nanopolymersomes. In conclusion, size and dispersity were strongly influenced by duration of magnetic stirring and overall composition of organic/aqueous media; however, size and dispersity were retained against different degrees of dilution. PolyDoxSome was able to control the release of doxorubicin in pH dependent manner and effectively deliver the drug in active form to MCF-7 breast cancer cells.

Formulation of a novel oxybenzone-loaded nanostructured lipid carriers (NLCs)

The objective of the current study was to formulate oxybenzone into nanostructured lipid carriers (NLCs) to enhance its sunscreening efficacy and safety. NLCs of oxybenzone were prepared by the solvent diffusion method. A complete 2(3) factorial design was used for the evaluation of the prepared oxybenzone NLCs. The study design involves the investigation of the effect of three independent variables namely liquid lipid type (Miglyol 812 and oleic acid), liquid lipid concentration (15% and 30%), and oxybenzone concentration (5% and 10% with respect to total lipids) on the particle size (p.s.) , the entrapment efficiency (EE%) and the in vitro drug release after 8 h. The prepared NLCs were spherical in overall shape and were below 0.8 microm. Miglyol 812 and 30% liquid lipid were found to significantly decrease the p.s. and increase the EE% when compared to oleic acid and 15% liquid lipid. Increasing oxybenzone concentration increased significantly the p.s. but did not affect the EE%. NLCs prepared using Miglyol 812, 15% liquid lipid, and 10% oxybenzone showed slower drug release when compared to those prepared using oleic acid, 30% liquid lipid, and 5% oxybenzone, respectively. The candidate oxybenzone-loaded NLC dispersion was then formulated into gel. The incorporation of oxybenzone into NLCs greatly increased the in vitro sun protection factor and erythemal UVA protection factor of oxybenzone more than six- and eightfold, respectively, while providing the advantage of overcoming side effects of free oxybenzone as evidenced by very low irritation potential.

Development of a new delivery system consisting in 'drug-in cyclodextrin-in PLGA nanoparticles'

A combined approach based on drug cyclodextrin (CD) complexation and loading into PLGA nanoparticles (NP) has been developed to improve oxaprozin therapeutic efficiency. This strategy exploits the solubilizing and stabilizing properties of CDs and the prolonged-release and targeting properties of PLGA NPs. Drug-loaded NPs, prepared by double-emulsion, were examined for dimensions, zeta-potential and entrapment efficiency. Solid-state studies demonstrated the absence of drug-polymer interactions and assessed the amorphous state of the drug-CD complex loaded into NPs. Drug release rate from NPs was strongly influenced by the presence and kind of CD used. The percentage released at 24 h varied from 16% (plain drug-loaded NPs) to 50% (drug-betaCD-loaded NPs) up to 100% (drug-methylbetaCD-loaded NPs). This result suggests the possibility of using CD complexation not only to promote, but also to regulate drug release rate from NPs, by selecting the proper type of CD or CD combination.

Nanoparticulate delivery of novel drug combination regimens for the chemoprevention of colon cancer

The purpose of this work was to assess synergistic inhibitory responses of a novel chemopreventive combination regimen of drugs namely, aspirin in combination with calcium and folic acid on two human colon cancer cell lines, HT-29 and SW-480. Subsequently, based on positive responses, nanotechnology-based formulations were developed for the targeted delivery of these combinatorial regimens to the colon for the chemoprevention of colon cancer. Additionally, conventional drug formulations using controlled release polymers chitosan, pectin and hydroxypropyl methylcellulose (HPMC) were tested for release of the drugs, for comparison purposes. Chemopreventive combination regimens demonstrated significant synergistic efficacy in both cell lines from XTT assay studies, when compared to the effects of individual agents. Approximately 45% decrease in cell viability for aspirin (15 mM) and calcium (30 mM) mixtures was observed in HT-29 cell lines, compared to approximately 55% decrease by the same combination in SW-480 cell lines. With combinations of aspirin (5 mM) and folic acid (1.5 mM), HT-29 cells demonstrated a 30% decrease in cell viability compared to approximately 38% decrease in the SW-480 cell line. Overall, all drug combinations demonstrated significant synergistic responses in the cell lines tested with the SW-480 cell line being more significantly affected by the drug regimens than the HT-29 cell line. Drug encapsulated nanoparticles demonstrated a spherical morphology, <125 nm average particle size (aspirin and folic acid) of nanoparticles and encapsulation efficiencies in the range of 80-91%. Drug release from nanoparticles was controlled with approximately 60% of the original amount released over a 96 h period. Conventional formulations exhibited faster kinetics of drug release when compared to the PLGA nanoparticles. Overall, the cell line studies demonstrate, for the first time, the ability of novel chemopreventive combinations to inhibit the growth of colon cancer cells whereas the nanotechnology-based drug delivery system provides valuable evidence for targeted therapy towards colon cancer chemoprevention.

Formulation, characterization and pharmacokinetics of praziquantel-loaded hydrogenated castor oil solid lipid nanoparticles

Aim: The purpose of this study was to formulate praziquantel (PZQ)-loaded hydrogenated castor oil (HCO) solid lipid nanoparticles (SLN) to enhance the bioavailability and prolong the systemic circulation of the drug. Materials & methods: PZQ was encapsulated into HCO nanoparticles by a hot homogenization and ultrasonication method. The physicochemical characteristics of SLN were investigated by optical microscope, scanning electron microscopy and photon correlation spectroscopy. Pharmacokinetics were studied after oral, subcutaneous and intramuscular administration in mice. Results: The diameter, polydispersivity index, ζ potential, encapsulation efficiency and loading capacity of the nanoparticles were 344.0 ± 15.1 nm, 0.31 ± 0.08, -16.7 ± 0.5 mV, 62.17 ± 6.53% and 12.43 ± 1.31%, respectively. In vitro release of PZQ-loaded HCO-SLN exhibited an initial burst release followed by a sustained release. SLN increased the bioavailability of PZQ by 14.9-, 16.1- and 2.6-fold, and extended the mean residence time of the drug from 7.6, 6.6 and 8.2 to 95.9, 151.6 and 48.2 h after oral, subcutaneous and intramuscular administration, respectively. Conclusion: The PZQ-loaded HCO-SLN could be a promising formulation to enhance the pharmacological activity of PZQ.

Cationic surface modification of PLG nanoparticles offers sustained gene delivery to pulmonary epithelial cells

Biodegradable polymeric nanoparticles are currently being explored as a nonviral gene delivery system; however, many obstacles impede the translation of these nanomaterials. For example, nanoparticles delivered systemically are inherently prone to adsorbing serum proteins and agglomerating as a result of their large surface/volume ratio. What is desired is a simple procedure to prepare nanoparticles that may be delivered locally and exhibit minimal toxicity while improving entry into cells for effectively delivering DNA. The objective of this study was to optimize the formulation of poly(D,L-lactide-co-glycolide) (PLG) nanoparticles for gene delivery performance to a model of the pulmonary epithelium. Using a simple solvent diffusion technique, the chemistry of the particle surface was varied by using different coating materials that adsorb to the particle surface during formation. A variety of cationic coating materials were studied and compared to more conventional surfactants used for PLG nanoparticle fabrication. Nanoparticles (approximately 200 nm) efficiently encapsulated plasmids encoding for luciferase (80-90%) and slowly released the same for 2 weeks. In A549 alveolar lung epithelial cells, high levels of gene expression appeared at day 5 for certain positively charged PLG particles and gene expression was maintained for at least 2 weeks. In contrast, PEI gene expression ended at day 5. PLG particles were also significantly less cytotoxic than PEI suggesting the use of these vehicles for localized, sustained gene delivery to the pulmonary epithelium.

Applications of novel drug delivery system for herbal formulations

Over the past several years, great advances have been made on development of novel drug delivery systems (NDDS) for plant actives and extracts. The variety of novel herbal formulations like polymeric nanoparticles, nanocapsules, liposomes, phytosomes, nanoemulsions, microsphere, transferosomes, and ethosomes has been reported using bioactive and plant extracts. The novel formulations are reported to have remarkable advantages over conventional formulations of plant actives and extracts which include enhancement of solubility, bioavailability, protection from toxicity, enhancement of pharmacological activity, enhancement of stability, improved tissue macrophages distribution, sustained delivery, and protection from physical and chemical degradation. The present review highlights the current status of the development of novel herbal formulations and summarizes their method of preparation, type of active ingredients, size, entrapment efficiency, route of administration, biological activity and applications of novel formulations.

Surface modifications of nanocarriers for effective intracellular delivery of anti-HIV drugs

A variety of nanocarriers such as bioconjugates, dendrimers, liposomes, and nanoparticles have been widely evaluated as potential targeted drug delivery systems. Passive targeting of nanoscale carriers is based on a size-flow-filtration phenomenon that is usually limited to tumors, the reticular endothelial system, and possibly lymph nodes (LNs). In fact, targeting the delivery of drugs to pivotal physiological sites such as the lymph nodes has emerged as a promising strategy in treating HIV disease. Ligands for specific cell surface receptors can be displayed on nanocarriers in order to achieve active targeting. The approach has been extensively used preclinically in cancer where certain receptors are over-expressed at various stages of the disease. Unfortunately, markers of HIV infection are lacking and latently infected cells do not show any signs of infection on their surface. However, the disease naturally targets only a few cell types. The HIV receptor CD4, coreceptors (CCR5 and CXCR4), and some receptors relatively specific for macrophages provide potentially valuable surface targets for drug delivery to all susceptible cells in patients infected by HIV. This review focuses on nanoscale targeting with an emphasis on surface modifications of drug delivery nanocarriers for active targeting. A number of related issues, including HIV biology, targets, pharmacokinetics, and intracellular fate as well as literature-cited examples of emerging surface-modified targeted carrier systems are discussed.

Crystalline drug aconitine-loaded poly(d,l-lactide-coglycolide) nanoparticles: preparation and in vitro release

This paper reports both the optimization of aconitine entrapment and its release from biodegradable poly(d,l-lactide-coglycolide) (PLGA) nanoparticles prepared using the O/W single-emulsion/solvent-evaporation technique. The influence of several parameters, such as the initial aconitine mass, aqueous-phase pH, volume ratio of aqueous/organic phase (W/O), PLGA concentration in the organic phase, etc., on aconitine encapsulation were investigated. The optimized nanoparticles had an entrapment efficiency of 88.40+/-3.02% with drug loading capacity of 9.42+/-2.93%. Crystallization growth, which played a crucial role in hindering the incorporation of aconitine into the polymer carrier, was proposed. Differential scanning calorimetry and X-ray powder diffraction demonstrated that aconitine existed in an amorphous state or as a solid solution in the polymeric matrix. The in vitro release profiles exhibited a sustained release of aconitine from nanoparticles and a pH-dependent character in phosphate-buffered saline with different pH values. Moreover, aconitine-loaded PLGA nanoparticles could lead to improvement in the stability of aconitine. This work demonstrated the feasibility of encapsulating aconitine into PLGA nanoparticles using the O/W single-emulsion/solvent-evaporation technique.

Evaluation of alkyl polyglucoside as an alternative surfactant in the preparation of peptide-loaded nanoparticles

The present study was carried out to evaluate potentials of alkyl polyglucoside (APG) as an alternative surfactant/stabilizer in the preparation of peptide-loaded nanoparticles. hGF(2) (human gel filtration fraction 2) was used as a model peptide and APG based on C(10) fatty alcohol (decyl polylglucoside) was used as a representative surfactant. PLA (poly D,L-lactide) and PLGA (poly D,L-lactide-co-glycolide) based nanoparticles were prepared and the effect of APG on particle size, entrapment efficiency and biological activity was evaluated. At a concentration as low as 0.05% w/v, APG provided an excellent stabilization effect, resulting in nanoparticles with better encapsulation efficiency and particle size well below 450 nm. The effective concentration of APG was found to be much less (10-fold) as compared to PVA. Moreover, APG also showed low residual content as compared to PVA. In-vitro and in-vivo biological activity evaluation confirmed that encapsulated peptide was compatible with APG. These preliminary results suggest that APGs can be used as alternate surfactants for nanoparticle preparation.

Sparfloxacin-loaded PLGA nanoparticles for sustained ocular drug delivery

Poor ocular bioavailability of drugs (<1%) from conventional eye drops (ie, solution, suspension, and ointments) is mainly due to the physiologic barriers of the eye. In general, ocular efficacy is closely related to ocular drug bioavailability, which may be enhanced by increasing corneal drug penetration and prolonging precorneal drug residence time. In our current work, we develop and evaluate a new colloidal system, that is, poly(dl-lactide-co-glycolide) (PLGA) nanoparticles for sparfloxacin ophthalmic delivery, to improve precorneal residence time and ocular penetration. Nanoparticles were prepared by nanoprecipitation technique and characterized for various properties such as particle size, zeta potential, in vitro drug release, statistical model fitting, stability, and so forth. Microbiological assay was carried out against Pseudomonas aeruginosa using the cup-plate method. Precorneal residence time was studied in albino rabbits by gamma scintigraphy after radiolabeling of sparfloxacin by Tc-99m. Ocular tolerance of the developed nanosuspension was also studied by the Hen Egg Test-Chorioallantoic Membrane (HET-CAM) method. The developed nanosuspension showed a mean particle size in the range of 180 to 190 nm, suitable for ophthalmic application with zeta potential of -22 mV. In vitro release from the developed nanosuspension showed an extended release profile of sparfloxacin according to the Peppas model. Acquired gamma camera images showed good retention over the entire precorneal area for the developed nanosuspension compared with that of a marketed formulation. The marketed drug formulation cleared very rapidly from the corneal region and reached the systemic circulation through the nasolacrimal drainage system, as significant radioactivity was recorded in kidney and bladder after 6 hours of ocular administration, whereas the developed nanosuspension cleared at a very slow rate (P < .05) and remained at the corneal surface for longer duration, as no radioactivity was observed in the systemic circulation. HET-CAM assay with 0 score in 8 hours indicates the nonirritant property of the developed nanosuspension. The developed lyophilized nanosuspension was found to be stable for a longer duration of time than the conventional marketed formulation with a good shelf life.

FROM THE CLINICAL EDITOR

Poor ocular bioavailability of drugs (<1%) from conventional eye drops is mainly due to the eye physiological barriers. In this study, a new colloidal system, PLGA nanoparticle for sparfloxacin ophthalmic delivery was demonstrated to improve precorneal residence time and ocular penetration. The developed lyophilized nanosuspension was found to be stable for longer duration of time than conventional marketed formulations.

Poly (epsilon-caprolactone) microparticles containing Levobunolol HCl prepared by a multiple emulsion (W/O/W) solvent evaporation technique: effects of some formulation parameters on microparticle characteristics

The aim of this study was to prepare poly (epsilon-caprolactone) (PCL) microparticles of Levobunolol HC1 (L-HC1) for use as an anti-glaucomatous drug to the eye. The double emulsion (W/O/W) solvent evaporation technique was used for encapsulating L-HC1 as a hydrophilic drug. The study examined the impact of different factors including the pH and volume of the external aqueous phase, the concentration of polyvinylalcohol (PVA) and Pluronic F68 (PF68) used as stabilizers and drug/polymer ratios on the characteristics of the microparticles. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were used to identify the physical state of the drug and polymer. The zeta potential of the particles was also identified. Entrapment efficiency was found to be highest with a 0.5% PVA concentration and 100 mL volume of external aqueous phase at pH 12. The high efficiency was due to a reduction in the degree of drug ionization. The microparticles were spherical and appropriately sized for ophthalmic application. Drug release from the microparticles appears to consist of two components, with an initial rapid release followed by a slower stage. Drug release was slower when the microparticle was incorporated into the thermally reversible gel (Pluronic F127) in comparison to drug release from the free drug incorporated into the gel and drug release from the free microparticle.

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.

Targeted nanomedicines: effective treatment modalities for cancer, AIDS and brain disorders

Novel technology in the nanomedicine field is expected to develop innovative products as targeted drug-delivery approaches. Targeted drug delivery of various drugs for the treatment of cancer, AIDS and brain disorders is the primary research area in which nanomedicines have a major role and need. This review is concerned with emerging targeted nanomedicines (polymeric nanoparticles, solid lipid nanoparticles, polymeric micelles, dendrimers, liposomes, gold nanoparticles and magnetic nanoparticles) and multifunctional carriers capable of combining targeted drug delivery and imaging (polymeric micelles, dendrimers and magnetic nanoparticles) in the field of pharmaceutical applications. The significant toxicity issues associated with these nanomedicines are also explored here.

Celecoxib-loaded poly(D,L-lactide-co-glycolide) nanoparticles prepared using a novel and controllable combination of diffusion and emulsification steps as part of the salting-out procedure

A novel procedure for the manufacture of celecoxib-loaded poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles is described that is based upon combining salting out and emulsion-evaporation steps. An entrapment efficiency, a measure of the actual to theoretical drug content, of 97.3% was achieved, being superior to that achieved when these popular techniques were used separately (emulsion evaporation, 40.1%; salting out, 10.0%). The ratio of a water miscible solvent (acetone) to a non water-miscible solvent (dichloromethane) was shown to be the primary determinants of size and drug loading. Once optimized, using an organic phase of 3 : 1 acetone : dichloromethane vol : vol ratio, further control on particle parameters could be exerted using modification of acetone diffusion by alterations in MgCl2 x 6H2O concentration. This step was shown to have a small effect on both the mean nanoparticle size and entrapment efficiency, but found to reduce the polydispersity considerably. Diffusion control using a 45% w/v MgCl2 x 6H2O solution produced nanoparticles with a mean size of 151.4 nm, a polydispersity index of 0.023 and 98.1% entrapment efficiency. Electron microscopy showed the particles to be smooth and spherical. Sheer homogenization during the emulsification step was shown to be not as effective as sonication, with the latter technique able to produce nanoparticles after 1 min of application. Drug release studies across a semi-permeable membrane demonstrated a reduction in the burst effect as the ratio of acetone in the organic phase was increased. Calorimetry studies suggested that celecoxib existed in the nanoparticle as a molecular dispersion, with additional evidence for a strong interaction between the PLGA and the absorbed poly(vinyl alcohol) stabilizer. Formation of a strong interaction between celecoxib and PLGA, together with the formation of a radial drug gradient give a release profile that does not possess the prevalent burst effect seen with other nanoparticulate drug-loaded systems.

Artificial Neural Networks: Comparison of Two Programs for Modeling a Process of Nanoparticle Preparation

Artificial Neural Networks (ANNs) were used to predict nanoparticle size and micropore surface area of polylactic acid nanoparticles, prepared by a double emulsion method. Different batches were prepared while varying polymer and surfactant concentration, as well as homogenization pressure. Two commercial ANNs programs were evaluated: Neuroshell Predictor, a black-box software adopting both neural and genetic strategies, and Neurosolutions, allowing a step-by-step building of the network. Results were compared to those obtained by statistical method. Predictions from ANNs were more accurate than those calculated using non-linear regression. Neuroshell Predictor allowed quantification of the relative importance of the inputs. Furthermore, by varying the network topology and parameters using Neurosolutions, it was possible to obtain output values which were closer to experimental values. Therefore, ANNs represent a promising tool for the analysis of processes involving preparation of polymeric carriers and for prediction of their physical properties.

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.

Effect of different formulation variables on some particle characteristics of poly (DL-lactide-co-glycolide) nanoparticles

This study investigates the effect of some formulation variables on particulate characteristics of poly (DL-lactide-co-glycolide) (PLGA) copolymer nanoparticles by applying 2(3) factorial design and response surface methodology (RSM). Nanoparticles were prepared by solvent displacement technique. Initially, appropriate formulation factors for elaboration of polymeric particles were selected by screening. A 2(3) full factorial design was employed to evaluate the influence of three formulation variables, polymer concentration (X(1)), dispersant concentration (X(2)) and phase volume ratio (X(3)) on the percentage of total particles at submicron range (Y(1)), mean diameter (Y(2)) and specific surface area (Y(3)) as particle characteristics. The results showed that all the three variables had significant influence on mean diameter of particles and amount of particles at submicron range. Simultaneous change of polymer concentration and dispersant concentration had significant effect on specific surface area of particles. Span value as an index of polydispersity indicated uniformity in particle size distribution.

Nanoparticles with entrapped α-tocopherol: synthesis, characterization, and controlled release

An emulsion evaporation method was used to synthesize spherical poly(DL-lactide-co-glycolide) (PLGA) nanoparticles with entrapped α-tocopherol. Two different surfactants were used: sodium dodecyl sulfate (SDS) and poly(vinyl alcohol) (PVA). For SDS nanoparticles, the size of the nanoparticles decreased significantly with the entrapment of α-tocopherol in the PLGA matrix, while the size of PVA nanoparticles remained unchanged. The polydispersity index after synthesis was under 0.100 for PVA nanoparticles and around 0.150 for SDS nanoparticles. The zeta potential was negative for all PVA nanoparticles. The entrapment efficiency of α-tocopherol in the polymeric matrix was approximately 89% and 95% for nanoparticles with 8% and 16% α-tocopherol theoretical loading, respectively. The residual PVA associated with the nanoparticles after purification was approximately 6% ( w/w relative to the nanoparticles). The release profile showed an initial burst followed by a slower release of the α-tocopherol entrapped inside the PLGA matrix. The release for nanoparticles with 8% α-tocopherol theoretical loading (86% released in the first hour) was faster than the release for the nanoparticles with 16% α-tocopherol theoretical loading (34% released in the first hour).

Nanoparticles formulation of Cuscuta chinensis prevents acetaminophen-induced hepatotoxicity in rats

Cuscuta chinensis is a commonly used traditional Chinese medicine to nourish the liver and kidney. Due to the poor water solubility of its major constituents such as flavonoids and lignans, its absorption upon oral administration could be limited. The purpose of the present study was to use the nanosuspension method to prepare C. chinensis nanoparticles (CN), and to compare the hepatoprotective and antioxidant effects of C. chinensis ethanolic extract (CE) and CN on acetaminophen-induced hepatotoxicity in rats. An oral dose of CE at 125 and 250 mg/kg and CN at 25 and 50mg/kg showed a significant hepatoprotective effect relatively to the same extent (P<0.05) by reducing levels of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. These biochemical assessments were supported by rat hepatic biopsy examinations. In addition, the antioxidant activities of CE and CN both significantly increased superoxide dismutase, catalase, glutathione peroxidase, and reduced malondialdehyde (P<0.05). Moreover, the results also indicated that the hepatoprotective and antioxidant effects of 50 mg/kg CN was effectively better than 125 mg/kg CE (P<0.05), and an oral dose of CN that is five times as less as CE could exhibit similar levels of outcomes. In conclusion, we suggest that the nanoparticles system can be applied to overcome other water poorly soluble herbal medicines and furthermore to decrease the treatment dosage.

Dual agents loaded PLGA nanoparticles: systematic study of particle size and drug entrapment efficiency

PLGA nanoparticles simultaneously loaded with vincristine sulfate (VCR) and quercetin (QC) were prepared via O/W emulsion solvent evaporation. Six independent processing parameters and PLGA characteristics were assessed systematically to enhance the incorporation of the dual agents with different properties (VCR and QC, hydrophilic and hydrophobic molecule, respectively) into PLGA nanoparticles and control particle size. Approaches investigated for the enhancement of drug entrapment efficiencies and the controlling of particle size included the influence of the molecular weight (MW) of PLGA and the lactide-to-glycolide (L:G) ratio of PLGA, PLGA concentration, PVA concentration, initial QC content, acetone-to-dichloromethane (A/D) volume ratio, aqueous phase pH and aqueous to organic phase (W/O) volume ratio. The nanoparticles produced by optimal formulation were submicron size (139.5+/-4.3 nm, n=3) with low polydispersity index (0.095+/-0.031, n=3). Nanoparticles observed by transmission electron microscopy (TEM) showed extremely spherical shape. The entrapment efficiencies determined by high performance liquid chromatography (HPLC) by ultracentrifuge method were 92.84+/-3.37% for VCR and 32.66+/-2.92% for QC (n=3). The drug loadings were 0.0037+/-0.0001% for VCR and 1.36+/-0.12% for QC (n=3).