Body distribution of azidothymidine bound to nanoparticles after oral administration

Enhancement of the transdermal delivery of zidovudine by pretreating the skin with two physical enhancers: microneedles and sonophoresis

BACKGROUND

Zidovudine (AZT) has been the most widely used drug for antiretroviral therapy. In order to improve the therapy with this drug, different alternatives have been proposed, such as the transdermal administration. The use of permeation enhancers is necessary to favor the passage of this drug through the skin, due to its physicochemical properties and to the natural permeation barrier imposed by the skin.

OBJECTIVES

To evaluate the effect of two permeation enhancers, sonophoresis and microneedles, on the permeability of AZT through the skin.

METHODS

Permeation studies with an AZT solution were performed using pigskin clamped in Franz-type cells. Sonophoresis was applied under different conditions (i.e., amplitude, duty cycle and application time), selected according to an experimental design, where the response variables were the increase in temperature of the skin surface and the increase in transepidermal water loss. ATR-FTIR was also used to demonstrate the effect of enhancers on membrane components.

RESULTS

The permeability of AZT through intact skin was very poor, with a very long lag time. Pretreatment of the skin with sonophoresis increased AZT transport significantly, reducing the lag time. The maximum flux (27.52 µgcm^-2 h^-1) and the highest total amount permeated (about 624 µg/cm²) were obtained when applying sonophoresis in continuous mode, with an amplitude of 20%, and an application time of 2 min. Sonophoresis appears to have an impact on stratum corneum proteins. The use of microneedles further increased the flux (30.41 µgcm^-2 h^-1) and the total amount permeated (about 916 µg/cm²), relative to sonophoresis.

CONCLUSION

The results are encouraging in terms of promoting AZT transport through the skin using sonophoresis or microneedles as permeation enhancers.

N,N,N-trimethylchitosan-poly (n-butylcyanoacrylate) core-shell nanoparticles as a potential oral delivery system for acyclovir

This study investigated the feasibility of polysaccharide-coated poly(n-butyl cyanoacrylate) (PBCA) nanoparticles for oral delivery of acyclovir (ACV). PBCA nanoparticles were obtained by the emulsion polymerization method. Chitosan was chemically modified to obtain N,N,N-trimethylchitosan (TMC), which was used to coat the nanoparticles (PBCA-TMC). Nanoparticles were characterized by dynamic light scattering, zeta potential, differential scanning calorimetry (DSC), atomic force microscopy (AFM), cytotoxicity, and the effect on the transepithelial electrical resistance (TEER) of the Caco-2 cells. The size of the coated nanoparticles (296.2 nm) was significantly larger than uncoated (175.0 nm). Furthermore, PBCA nanoparticles had a negative charge (-11.7 mV), which was inverted to highly positive values (+36.5 mV) after coating. DSC analysis suggested the occurrence of the coating, which was confirmed by AFM images. The MTT assay revealed concentration-dependent cytotoxicity for the core-shell nanoparticles. Additionally, PBCA-TMC caused a significant but reversible decrease in the Caco-2 cell monolayer TEER. Entrapped ACV (PBCA-ACV-TMC), a Biopharmaceutical Classification System class III drug substance, increased approximately 3.25 times the Papp of ACV in the Caco-2 permeability assay. The nanoparticles were also able to provide in vitro ACV controlled release using media with different pH values (1.2; 6.8; 7.4). Accordingly, this new core-shell nanoparticle showed the potential to improve the oral delivery of ACV.

Pharmaceutical Approaches to HIV Treatment and Prevention

Human immunodeficiency virus (HIV) infection continues to pose a major infectious disease threat worldwide. It is characterized by the depletion of CD4+ T cells, persistent immune activation, and increased susceptibility to secondary infections. Advances in the development of antiretroviral drugs and combination antiretroviral therapy have resulted in a remarkable reduction in HIV-associated morbidity and mortality. Antiretroviral therapy (ART) leads to effective suppression of HIV replication with partial recovery of host immune system and has successfully transformed HIV infection from a fatal disease to a chronic condition. Additionally, antiretroviral drugs have shown promise for prevention in HIV pre-exposure prophylaxis and treatment as prevention. However, ART is unable to cure HIV. Other limitations include drug-drug interactions, drug resistance, cytotoxic side effects, cost, and adherence. Alternative treatment options are being investigated to overcome these challenges including discovery of new molecules with increased anti-viral activity and development of easily administrable drug formulations. In light of the difficulties associated with current HIV treatment measures, and in the continuing absence of a cure, the prevention of new infections has also arisen as a prominent goal among efforts to curtail the worldwide HIV pandemic. In this review, the authors summarize currently available anti-HIV drugs and their combinations for treatment, new molecules under clinical development and prevention methods, and discuss drug delivery formats as well as associated challenges and alternative approaches for the future.

Nanopharmaceuticals as a solution to neglected diseases: Is it possible?

The study of neglected diseases has not received much attention, especially from public and private institutions over the last years, in terms of strong support for developing treatment for these diseases. Support in the form of substantial amounts of private and public investment is greatly needed in this area. Due to the lack of novel drugs for these diseases, nanobiotechnology has appeared as an important new breakthrough for the treatment of neglected diseases. Recently, very few reviews focusing on filiarasis, leishmaniasis, leprosy, malaria, onchocerciasis, schistosomiasis, trypanosomiasis, and tuberculosis, and dengue virus have been published. New developments in nanocarriers have made promising advances in the treatment of several kinds of diseases with less toxicity, high efficacy and improved bioavailability of drugs with extended release and fewer applications. This review deals with the current status of nanobiotechnology in the treatment of neglected diseases and highlights how it provides key tools for exploring new perspectives in the treatment of a wide range of diseases.

Improving bioavailability and biodistribution of anti-HIV chemotherapy

In the context of the treatment of HIV/AIDS, many improvements have been achieved since the introduction of the combination therapy (HAART). Nevertheless, no cure for this disease has been so far possible, because of some particular features of the therapies. Among them, two important ones have been selected and will be the subject of this review. The first main concern in the treatments is the poor drug bioavailability, resulting in repeated administrations and therefore a demanding compliance (drug regimens consist of multiple drugs daily intake, and non-adherence to therapy is among the important reasons for treatment failure). A second important challenge is the need to target the drugs into the so-called reservoirs and sanctuaries, i.e. cells or body compartments where drugs cannot penetrate or are distributed in sub-active concentrations. The lack of antiviral action in these regions allows the virus to lie latent and start to replicate at any moment after therapy suspension. Recent drug delivery strategies addressing these two limitations will be presented in this review. In the first part, strategies to improve the bioavailability are proposed in order to overcome the absorption or the target cell barrier, or to extend the efficacy time of drugs. In the second section, the biodistribution issues are considered in order to target the drugs into the reservoirs and the sanctuaries, in particular the mononuclear phagocyte system and the brain.

Development of quercetin nanoformulation and in vivo evaluation using streptozotocin induced diabetic rat model

Quercetin-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (Qu-NP) were prepared by emulsion-diffusion-evaporation method and characterized as 179.9 ± 11.2 nm in size with 0.128 as polydispersity index, more than 86% drug entrapment efficiency, and zeta potential was -6.06 ± 1.51 mV. D-Trehalose (5% w/v) was found to be a suitable cryoprotectant for lyophilization of Qu-NP, and antioxidant assays indicated that Qu-NP were able to retain the antioxidant property similar to that of free drug at equivalent concentration after formulation development. In vitro release study of Qu-NP showed a controlled release pattern of quercetin. An enhanced oral bioavailability (523% relative increase) was observed in pharmacokinetic study with a 6-day sustained release from Qu-NP as compared to quercetin suspension, which indicated the reduced dosing frequency. Efficacy in diabetic rats suggested that same dose of Qu-NP on every fifth day was sufficient to bring effect similar to daily dose of oral quercetin suspension, and the same effect was also observed for catalase and superoxide dismutase levels in pancreas and kidneys. Thus, the system offers an efficacious oral therapy with reduced dose and dosing frequency for treatment of diabetes and is hence patient compliant.

Brain-targeted polymeric nanoparticles: in vivo evidence of different routes of administration in rodents

AIMS, MATERIALS & METHODS: The capacity of polymeric nanoparticles (NPs) to reach the target regardless of the administration route is a neglected field of investigation in pharmaceutical nanotechnology. Therefore, after having demonstrated in previous studies that glycopeptide-engineered NPs (g7-NPs) were able to reach the brain after intravenous administrations in rodents, this article aims to evaluate whether they can reach the CNS when administered by different routes.

RESULTS & CONCLUSIONS

The confocal microphotographs on murine brain sections showed the capability of g7-NPs to reach the target also after intraperitoneal, intranasal and oral administrations. This could open new vistas for the future application of g7-NPs in the therapeutic treatment of CNS diseases.

Engineered nanoparticulate drug delivery systems: the next frontier for oral administration?

For the past few decades, there has been a considerable research interest in the area of oral drug delivery using nanoparticle (NP) delivery systems as carriers. Oral NPs have been used as a physical approach to improve the solubility and the stability of active pharmaceutical ingredients (APIs) in the gastrointestinal juices, to enhance the intestinal permeability of drugs, to sustain and to control the release of encapsulated APIs allowing the dosing frequency to be reduced, and finally, to achieve both local and systemic drug targeting. Numerous materials have been used in the formulation of oral NPs leading to different nanoparticulate platforms. In this paper, we review various aspects of the formulation and the characterization of polymeric, lipid, and inorganic NPs. Special attention will be dedicated to their performance in the oral delivery of drug molecules and therapeutic genes.

Nanotechnology and the treatment of HIV infection

Suboptimal adherence, toxicity, drug resistance and viral reservoirs make the lifelong treatment of HIV infection challenging. The emerging field of nanotechnology may play an important role in addressing these challenges by creating drugs that possess pharmacological advantages arising out of unique phenomena that occur at the “nano” scale. At these dimensions, particles have physicochemical properties that are distinct from those of bulk materials or single molecules or atoms. In this review, basic concepts and terms in nanotechnology are defined, and examples are provided of how nanopharmaceuticals such as nanocrystals, nanocapsules, nanoparticles, solid lipid nanoparticles, nanocarriers, micelles, liposomes and dendrimers have been investigated as potential anti-HIV therapies. Such drugs may, for example, be used to optimize the pharmacological characteristics of known antiretrovirals, deliver anti-HIV nucleic acids into infected cells or achieve targeted delivery of antivirals to the immune system, brain or latent reservoirs. Also, nanopharmaceuticals themselves may possess anti-HIV activity. However several hurdles remain, including toxicity, unwanted biological interactions and the difficulty and cost of large-scale synthesis of nanopharmaceuticals.

Improvements in transfection efficiency with chitosan modified poly(DL-lactide-co-glycolide) nanospheres prepared by the emulsion solvent diffusion method, for gene delivery

This study sought to evaluate the in vitro transfection efficiency of plasmid DNA (pDNA)-loaded chitosan-modified poly(DL-lactide-co-glycolide) nanospheres (CS-PLGA NS) in a gene-delivery system. Using the emulsion solvent diffusion (ESD) method, pDNA-loaded PLGA NS was prepared and the surface of the PLGA NS was modified by binding to CS. Gene transfection ability of CS-PLGA NS was examined in A549 cells. The luciferase gene was used as a reporter gene. The pattern of luciferase activity by pDNA-loaded CS-PLGA NS was initially weak, but gradually grew stronger before decreasing activity. These phenomena should be in accordance with the sustained-release profile of pDNA from PLGA NS in the cytosol and the pDNA protection against DNase. Positively charged CS-PLGA NS was found, by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay, not to exhibit cytotoxicity on A549 cells. These results suggest that CS-PLGA NS are potential contributors to efficient pDNA delivery due to their increased interactions with cells and lack of cytotoxic effects.

Pharmacokinetics, tissue distribution and relative bioavailability of puerarin solid lipid nanoparticles following oral administration

Puerarin has various pharmacological effects; however, poor water-solubility and low oral bioavailability limit its clinical utility. A delivery system of solid lipid nanoparticles could enhance its oral absorption. The objective of this study was to investigate the pharmacokinetics, tissue distribution and relative bioavailability of puerarin in rats after a single dose intragastric administration of puerarin solid lipid nanoparticles (Pue-SLNs). The puerarin concentrations in plasma and tissues were determined by rapid resolution liquid chromatography electrospray ionization-tandem mass spectrometry. The C(max) value of puerarin after the administration of Pue-SLNs was significantly higher than that obtained with puerarin suspension (0.33±0.05 μg/mL vs. 0.16±0.06 μg/mL, P<0.01). The T(max) value after the administration of the Pue-SLNs was significantly shorter than that after puerarin suspension administration (40±0 min vs. 110±15.49 min, P<0.01). The AUC(0→t) values of puerarin were 0.80±0.23 mg h/L, and 2.48±0.30 mg h/L after administration of the puerarin suspension and Pue-SLNs, respectively. Following administration of the Pue-SLNs, tissue concentrations of puerarin also increased, especially in the target organs such as the heart and brain. These data suggest that SLNs are a promising delivery system to enhance the oral bioavailability of puerarin.

Modified nanoprecipitation method to fabricate DNA-loaded PLGA nanoparticles

OBJECTIVE

The objective of this study was to formulate DNA-loaded poly(d,l-lactide-co-glycotide) (PLGA) nanoparticles by a modified nanoprecipitation method.

METHODS

DNA-loaded PLGA nanoparticles were prepared by the modified nanoprecipitation method and the double emulsion/solvent evaporation method. The characterizations of DNA-loaded nanoparticles such as entrapment efficiency, morphology, particle size, zeta potential, structural integrity of the loaded DNA, and stability of the loaded DNA in PLGA nanoparticles against DNase I, in vitro release, cell viability and in vitro transfection capability were investigated.

RESULTS

The resulted PLGA nanoparticles by the modified nanoprecipitation method had uniform spherical shape, narrow size distribution with average particles size near 200 nm, negative zeta potential of -12.6 mV at pH 7.4, and a sustained-release property in vitro. Plasmid DNA could be efficiently encapsulated into PLGA nanoparticles (> 95%) without affecting its intact conformation using this modified nanoprecipitation method, which was superior to the double emulsion/solvent evaporation method. The PLGA nanoparticles were much safer to A549 cell compared to commercial Lipofectamine 2000 and could successfully transfer plasmid-enhanced green fluorescent protein into A549 cells.

CONCLUSION

In conclusion, the modified nanoprecipitation method could be applied as an efficient way to fabricate DNA-loaded PLGA nanoparticles instead of the conventional double emulsion/solvent evaporation method.

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.

Nanotechnology-based systems for the treatment and prevention of HIV/AIDS

The HIV/AIDS pandemic is an increasing global burden with devastating health-related and socioeconomic effects. The widespread use of antiretroviral therapy has dramatically improved life quality and expectancy of infected individuals, but limitations of currently available drug regimens and dosage forms, alongside with the extraordinary adapting capacity of the virus, have impaired further success. Alongside, circumventing the escalating number of new infections can only be attained with effective and practical preventative strategies. Recent advances in the field of drug delivery are providing evidence that engineered nanosystems may contribute importantly for the enhancement of current antiretroviral therapy. Additionally, groundwork is also being carried out in the field nanotechnology-based systems for developing preventative solutions for HIV transmission. This manuscript reviews recent advances in the field of nanotechnology-based systems for the treatment and prevention of HIV/AIDS. Particular attention is given to antiretroviral drug targeting to HIV reservoirs and the usefulness of nanosystems for developing topical microbicides and vaccines.

Chitosan-modified poly(D,L-lactide-co-glycolide) nanospheres for improving siRNA delivery and gene-silencing effects

Chitosan (CS) surface-modified poly(d,l-lactide-co-glycolide) (PLGA) nanospheres (NS) for a siRNA delivery system were evaluated in vitro. siRNA-loaded PLGA NS were prepared by an emulsion solvent diffusion (ESD) method, and the physicochemical properties of NS were investigated. The level of targeted protein expression and siRNA uptake were examined in A549 cells. CS-modified PLGA NS exhibited much higher encapsulation efficiency than unmodified PLGA NS (plain-PLGA NS). CS-modified PLGA NS showed a positive zeta potential, while plain-PLGA NS were negatively charged. siRNA uptake studies by observation with confocal leaser scanning microscopy (CLSM) indicated that siRNA-loaded CS-modified PLGA NS were more effectively taken up by the cells than plain-PLGA NS. The efficiencies of different siRNA preparations were compared at the level of targeted protein expression. The gene-silencing efficiency of CS-modified PLGA NS was higher and more prolonged than those of plain-PLGA NS and naked siRNA. This result correlated with the CLSM studies, which may have been due to higher cellular uptake of CS-modified PLGA NS due to electrostatic interactions. It was concluded that CS-modified PLGA NS containing siRNA could provide an effective siRNA delivery system.

Fighting tuberculosis: old drugs, new formulations

This review reports the state of the art on innovative drug delivery strategies designed for antitubercular chemotherapeutics. The introduction contains the fundamental biological background concerning tuberculosis and a review of the current antitubercular therapy, and is followed by a critical report of the micrometric and nanometric particulate systems designed and investigated to improve tuberculosis chemotherapy.

Targeted delivery of nanoparticles for the treatment of lung diseases

Targeted delivery of drug molecules to organs or special sites is one of the most challenging research areas in pharmaceutical sciences. By developing colloidal delivery systems such as liposomes, micelles and nanoparticles a new frontier was opened for improving drug delivery. Nanoparticles with their special characteristics such as small particle size, large surface area and the capability of changing their surface properties have numerous advantages compared with other delivery systems. Targeted nanoparticle delivery to the lungs is an emerging area of interest. This article reviews research performed over the last decades on the application of nanoparticles administered via different routes of administration for treatment or diagnostic purposes. Nanotoxicological aspects of pulmonary delivery are also discussed.

Poly(L-lactic acid)/polyethylenimine nanoparticles as plasmid DNA carriers

Non-viral vectors such as liposomes, polycations, and nanoparticles have been used as gene delivery systems. In this study, we prepared and characterized biodegradable poly(L-lactic acid) (PLA)/polyethylenimine (PEI) nanoparticles as gene carriers. pCMV/beta-gal and pEGFP-C1 were utilized as model plasmid DNAs (pDNA). Nanoparticles were prepared using a double emulsion-solvent evaporation technique, and their pDNA binding capacity was assessed by agarose gel electrophoresis. Transfection was studied in HEK 293 and HeLa cell lines, and the transfection efficiencies were determined by beta-galactosidase assay or flow cytometry. Three kinds of PLA/PEI systems were studied by varying the molecular weight of PEI. The PLA/PEI 25K system had a higher transfection efficiency than the PLA/PEI 0.8K or PLA/PEI 750K systems. The transfection efficiency was found to be dependent on the ratio of PLA/PEI nanoparticles to pDNA with an optimum ratio of 60:1 (w/w). The cytotoxicity was dependent on the quantity of PLA/PEI nanoparticles used, but it was comparable to that of commercial Lipofectin. These results demonstrate the potential of PLA/PEI nanoparticles as gene carriers.

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.

Delivery systems to increase the selectivity of antibiotics in phagocytic cells

Many infectious diseases are caused by facultative organisms that are able to survive in phagocytic cells. The intracellular location of these microorganisms protects them from the host defence systems and from some antibiotics with poor penetration into phagocytic cells. One strategy used to improve the penetration of antibiotics into phagocytic cells is the use of carrier systems that deliver these drugs directly to the target cell. Delivery systems such as liposomes, micro/nanoparticles, lipid systems, conjugates, and biological carriers such as erythrocyte ghosts may contribute to increasing the therapeutic efficacy of antibiotics and antifungal agents in the treatment of infections caused by intracellular microorganisms. The main objective of this review is to analyze recent advances and current perspectives in the use of antibiotic delivery systems in the treatment of intracellular infections such as mycobacterial infections, brucellosis, salmonellosis, listeriosis, fungal infections, visceral leishmaniasis, and HIV.

Establishing chitosan coated PLGA nanosphere platform loaded with wide variety of nucleic acid by complexation with cationic compound for gene delivery

The purpose of this paper was to establish the surface modified poly(d,l-lactide-co-glycolide) (PLGA) nanosphere platform with chitosan (CS) for gene delivery by using the emulsion solvent diffusion (ESD) method. The advantages of this method are a simple process under mild conditions without sonication. This method requires essentially dissolving both polymer and drug in the organic solvent. Therefore a hydrophilic drug such as nucleic acid is hardly applied to the ESD method. Nucleic acid can easily form an ion-complex with cationic compound, which can be dissolved in the organic solvent. Thereafter, nucleic acid solubility for organic solution can increase by complexation with cationic compound. We used DOTAP as a cationic compound to increase the loading efficiency of nucleic acid. By coating the PLGA nanospheres with CS, the loading efficiency of nucleic acid in the modified nanospheres increased significantly. The release profile of nucleic acid from PLGA nanospheres exhibited sustained release after initial burst. The PLGA nanospheres coated with chitosan reduced the initial burst of nucleic acid release and prolonged the drugs releasing at later stage. Chitosan coated PLGA nanosphere platform was established to encapsulate satisfactorily wide variety of nucleic acid for an acceptable gene delivery system.

Recent advances in delivery systems for anti-HIV1 therapy

In the last years, different non-biological and biological carrier systems have been developed for anti-HIV1 therapy. Liposomes are excellent potential anti-HIV1 carriers that have been tested with drugs, antisense oligonucleotides, ribozymes and therapeutic genes. Nanoparticles and low-density lipoproteins (LDLs) are cell-specific transporters of drugs against macrophage-specific infections such as HIV1. Through a process of protein transduction, cell-permeable peptides of natural origin or designed artificially allow the delivery of drugs and genetic material inside the cell. Erythrocyte ghosts and bacterial ghosts are a promising delivery system for therapeutic peptides and HIV vaccines. Of interest are the advances made in the field of HIV gene therapy by the use of autologous haematopoietic stem cells and viral vectors for HIV vaccines. Although important milestones have been reached in the development of carrier systems for the treatment of HIV, especially in the field of gene therapy, further clinical trials are required so that the efficiency and safety of these new systems can be guaranteed in HIV patients.

Hybrid polymer nanocapsules enhance in vitro delivery of azidothymidine-triphosphate to macrophages

One of the main limitations in the use of nucleoside reverse transcriptase inhibitors (NRTIs) such as azidothymidine (AZT) lies in their poor intracellular activation by cellular kinases into their active tri-phosphorylated form. Thus, the direct administration of triphosphate NRTIs like azidothymidine-triphosphate (AZT-TP), has been considered for bypassing this metabolic bottleneck, but these molecules do not diffuse intracellularly, due to their too hydrophilic character. Therefore, poly(iso-butylcyanoacrylate) (PIBCA) aqueous-cored nanocapsules have been tested as carriers to overcome the cellular delivery of AZT-TP. However, encapsulation of AZT-TP remained challenging because this molecule, due to its relatively low molecular weight, rapidly leaked out of the nanocapsules. In this study, we show that association of AZT-TP to a cationic polymer such as poly(ethyleneimine) (PEI) allowed to reach high entrapment efficiency of AZT-TP in PIBCA nanocapsules (up to 90%) as well as gradual in vitro release. The resulting hybrid PIBCA/PEI nanocapsules efficiently delivered AZT-TP in vitro to macrophages: the cellular uptake was increased by 30-fold compared to the free molecule, reaching relevant cellular concentrations for therapeutic purposes.

Effect of nanoparticulate polybutylcyanoacrylate and methylmethacrylate-sulfopropylmethacrylate on the permeability of zidovudine and lamivudine across the in vitro blood-brain barrier

Effect of size of nanoscaled polybutylcyanoacrylate (PBCA) and methylmethacrylate-sulfopropylmethacrylate (MMA-SPM) on the permeability of zidovudine (AZT) and lamivudine (3TC) across the blood-brain barrier (BBB) was investigated. Also, influence of alcohol on the permeability of AZT and 3TC incorporated with the two polymeric nanoparticles (NPs) was examined. The loading efficiency and the permeability of AZT and 3TC decreased with an increase in the particle size of the two carriers. By employing PBCA NPs, the BBB permeability of AZT and that of 3TC became, respectively, 8-20 and 10-18 folds. Application of MMA-SPM NPs leaded to about 100% increase in the BBB permeability of the two drugs. In the presence of 0.5% ethanol, 4-12% enhancement in the BBB permeability of the two drugs was obtained in the current carrier-mediated system.

Physicochemical characterization of poly(l-lactic acid) and poly(d,l-lactide-co-glycolide) nanoparticles with polyethylenimine as gene delivery carrier

Polymer nanoparticles have been used as non-viral gene delivery systems and drug delivery systems. In this study, biodegradable poly(L-lactic acid) (PLA)/polyethylenimine (PEI) and poly(D,L-lactide-co-glycolide) (PLGA)/PEI nanoparticles were prepared and characterized as gene delivery systems. The PLA/PEI and PLGA/PEI nanoparticles, which were prepared by a diafiltration method, had spherical shapes and smooth surface characteristics. The size of nanoparticles was controlled by the amount of PEI, which acted as a hydrophilic moiety, which effectively reduced the interfacial energy between the particle surface and the aqueous media. The nanoparticles showed an excellent dispersive stability under storage in a phosphate-buffered saline solution for 12 days. The positive zeta-potentials for the nanoparticles decreased and changed to negative values with increasing plasmid DNA (pDNA) content. Agarose gel electrophoresis showed that the complex formation between the nanoparticles and the pDNA coincided with the zeta-potential results. The results of in vitro transfection and cell viability on HEK 293 cells indicated that the nanoparticles could be used as gene delivery carriers.

Formulation and characterization of spray-dried powders containing nanoparticles for aerosol delivery to the lung

Spray-drying is a common practice of powder preparation for a wide range of drugs. Spray-dried powders can be used to deliver particles to the lungs via a dry powder inhaler (DPI). The present study investigated the feasibility of developing a platform for aerosol delivery of nanoparticles. Lactose was used as the excipient and spray-dried with two different types of nanoparticles: gelatin and polybutylcyanoacrylate nanoparticles. Results showed that some carrier particles were hollow while others had a continuous matrix. Gelatin nanoparticles were incorporated throughout the matrix and sometimes accumulated at one end of the lactose. Polycyanoacrylate nanoparticles mostly clustered in different spots within the lactose carriers. The mean sizes of both nanoparticle types were characterized at two different times: before they were spray-dried and after they were redissolved from the spray-dried powders. Both nanoparticle types remained in the nano-range size after spray-drying. The mean nanoparticle sizes were increased by approximately 30% after spray-drying, though this increase was statistically significant only for the gelatin nanoparticles. Dispersion of the powder with an in-house passive dry powder inhaler and subsequent cascade impaction measurements showed that incorporation of the nanoparticles did not affect the fine particle fraction (FPF) or mass median aerodynamic diameter (MMAD) of the powders. FPF was approximately 40% while MMAD was 3.0+/-0.2 microm, indicating the present formulations yield aerosols of a suitable particle size for efficient lung delivery of nanoparticles. The present work demonstrates that nanoparticles can be delivered to the lungs via carrier particles that dissolve after coming in contact with the aqueous environment of the lung epithelium. This opens the way for new drug-targeting strategies using nanoparticles for pulmonary delivery of drugs and diagnostics.