Enhanced antioxidant effect of trans-resveratrol: potential of binary systems with polyethylene glycol and cyclodextrin.

Trans-resveratrol, a polyphenol extracted from Vitis vinifera, has different beneficial effects following its administration on the skin. Here the potential use of binary systems to enhance in vitro and in vivo activity of trans-resveratrol was investigated. Thus the aqueous solubility of trans-resveratrol was investigated in the presence of growing concentrations of polyethylene glycol (PEG) or ß-cyclodextrin (ßCD) as solubilizing excipients. Then, the solid dispersion of trans-resveratrol with PEG or inclusion complexes trans-resveratrol/ßCD were prepared and characterised by different methods. Cytotoxicity and inhibition of reactive oxygen species (ROS) following H2O2 challenge in the presence of trans-resveratrol, alone or associated to the excipients, was evaluated on human keratinocyte HaCaT cell line. Both the trans-resveratrol-containing binary systems induced significant reduction of H2O2-induced ROS production, especially in the case of ßCD that was selected for the following phase of the study. Thus, the effect of a cream containing trans-resveratrol, alone or associated to ßCD, on different skin parameters such as corneometry, colorimetry and elastometry, was evaluated on human volunteers. All patients showed a visible improvement of clinical conditions with a remarkable decrease of aging signs, but this effect was higher of the hemi face treated with the ßCD-containing formulation versus formulation containing trans-resveratrol alone.

Nanotechnologies to use bisphosphonates as potent anticancer agents: the effects of zoledronic acid encapsulated into liposomes.

Zoledronic acid (ZOL) is a potent amino-bisphosphonate used for the treatment of bone metastases with recently reported antitumor activity. However, the short plasma half-life and rapid accumulation in bone limits the use of ZOL as an antitumor agent in extraskeletal tissues. Therefore, we developed stealth liposomes encapsulating ZOL (LipoZOL) to increase extraskeletal drug availability. Compared to free ZOL, LipoZOL induced a stronger inhibition of growth of a range of different cancer cell lines in vitro. LipoZOL also caused significantly larger inhibition of tumor growth and increased the overall survival in murine models of human prostate cancer and multiple myeloma, in comparison with ZOL. Moreover, a strong inhibition of vasculogenetic events without evidence of necrosis in the tumor xenografts from prostate cancer was recorded after treatment with LipoZOL. We demonstrated both antitumor activity and tolerability of LipoZOL in preclinical animal models of both solid and hematopoietic malignancies, providing a rationale for early exploration of use of LipoZOL as a potential anticancer agent in cancer patients. FROM THE CLINICAL EDITOR: The short plasma half-life and rapid accumulation in bone limits the use of zoledronic acid as an antitumor agent in extraskeletal tissues. Therefore, stealth liposomes encapsulating ZOL (LipoZOL) have been developed to increase extraskeletal drug availability.

Improved delivery of angiogenesis inhibitors from PLGA:poloxamer blend micro- and nanoparticles.

Clinical studies have demonstrated the efficacy of new strategies in cancer therapy, such as chemotherapy and radiotherapy, associated to the administration of tumour vascularization inhibitors. A critical limitation for the clinical application of angiogenesis inhibitors relies in their instability in biological environment and high-dose requirements. This work has attempted to overcome this limitation by designing an adequate delivery vehicle consisting of PLGA:poloxamer blend micro- and nanoparticles. The potential of this delivery system was investigated for a new synthetic angiogenesis inhibitor named polyaminoacid JS-2892b. PLGA:poloxamer (ratio 10 : 1) blend microparticles were prepared by the oil-in-oil emulsion technique, while PLGA:poloxamer (ratio 1 : 1) blend nanoparticles were obtained by a modified solvent diffusion technique. The results showed that, by adjusting the formulation conditions, it was possible to efficiently encapsulate the polyaminoacid JS-2892b within PLGA:poloxamer micro- (particle size of 20 microm and encapsulation efficiency higher than 90%) and nanoparticles (particle size of less than 280 nm and encapsulation efficiency of 52%). In addition, the delivery of the polyaminoacid JS-2892b from the particles could be controlled, without altering its stability, for extended periods of time (from a few days to over a month). The release of the encapsulated compound was significantly affected by the particle size and the way the drug is dispersed into the polymeric matrix. Therefore, this study provides information about the formulation conditions and potential of biodegradable particles for the controlled release of polyaminoacid JS-2892b.

Oligonucleotide decoy to NF-kappaB slowly released from PLGA microspheres reduces chronic inflammation in rat.

Nuclear factor-kappaB (NF-kappaB) plays a key role in the expression of several genes involved in the immune and inflammatory process. Previously, we demonstrated that NF-kappaB activation can be significantly inhibited by a double stranded oligodeoxynucleotide (ODN). Nevertheless, the therapeutic use of ODN requires a delivery system able to improve poor crossing of cell membranes and rapid in vivo enzymatic degradation. Poly(D,L-lactide-co-glycolide) (PLGA) microspheres can increase ODN stability in biological environment and release the encapsulated drug in long time frames. Here, we used a decoy ODN against NF-kappaB and we investigated its effect, when administered in naked form or when delivered by PLGA microspheres, in a rat model of chronic inflammation. The subcutaneous implant of lambda-carrageenin-soaked sponges caused leukocyte infiltration and formation of granulation tissue which were inhibited up to 15 days by co-injection of microspheres releasing decoy ODN whereas naked decoy ODN showed this effect only up to 5 days. Molecular analysis performed on granulation tissue demonstrated an inhibition of NF-kappaB activation correlated to a decrease of tumor necrosis factor-alpha (TNF-alpha) and inducible nitric oxide synthase (iNOS) expression. Our results suggest that microspheres could be an useful tool to improve pharmacokinetics of decoy ODN and may represent a strategy to inhibit NF-kappaB activation in chronic inflammation.

Bioactivated collagen-based scaffolds embedding protein-releasing biodegradable microspheres: tuning of protein release kinetics.

In tissue engineering, the recapitulation of natural sequences of signaling molecules, such as growth factors, as occurring in the native extracellular matrix (ECM), is fundamental to support the stepwise process of tissue regeneration. Among the manifold of tissue engineering strategies, a promising one is based on the creation of the chrono-programmed presentation of different signaling proteins. This approach is based upon the integration of biodegradable microspheres, loaded with suitable protein molecules, within scaffolds made of collagen and, in case, hyaluronic acid, which are two of the fundamental ECM constituents. However, for the design of bioactivated gel-like scaffolds the determination of release kinetics must be performed directly within the tissue engineering template. In this work, biodegradable poly(lactic-co-glycolic)acid (PLGA) microspheres were produced by the multiple emulsion-solvent evaporation technique and loaded with rhodamine-labelled bovine serum albumin (BSA-Rhod), a fluorescent model protein. The microdevices were dispersed in collagen gels and collagen-hyaluronic acid (HA) semi-interpenetrating networks (semi-IPNs). BSA-Rhod release kinetics were studied directly on single microspheres through confocal laser scanning microscopy (CLSM). To thoroughly investigate the mechanisms governing protein release from PLGA microspheres in gels, BSA-Rhod diffusion in gels was determined by fluorescence correlation spectroscopy (FCS), and water transport through the microsphere bulk was determined by dynamic vapor sorption (DVS). Moreover, the decrease of PLGA molecular weight and glass transition temperature (T(g)) were determined by gel permeation chromatography (GPC) and differential scanning calorimetry (DSC), respectively. Results indicate that protein release kinetics and delivery onset strongly depend on the complex interplay between protein transport through the PLGA matrix and in the collagen-based release media, and water sequestration within the scaffolds, related to the scaffold hydrophilicity, which is dictated by HA content. The proper manipulation of all these features may thus allow the obtainment of a fine control over protein sequential delivery and release kinetics within tissue-engineering scaffolds.

Nano and microtechnologies for the delivery of oligonucleotides with gene silencing properties.

Oligonucleotides (ONs) are synthetic fragments of nucleic acid designed to modulate the expression of target proteins. DNA-based ONs (antisense, antigene, aptamer or decoy) and more recently a new class of RNA-based ONs, the small interfering RNAs (siRNAs), have gained great attention for the treatment of different disease states, such as viral infections, inflammation, diabetes, and cancer. However, the development of therapeutic strategies based on ONs is hampered by their low bioavailability, poor intracellular uptake and rapid degradation in biological fluids. The use of a non-viral carrier can be a powerful tool to overcome these drawbacks. Lipid or polymer-based nanotechnologies can improve biological stability and cellular uptake of ONs, with possibility of tissue and/or cellular targeting. The use of polymeric devices can also produce a prolonged release of the ON, thus reducing the need of frequent administrations. This review summarizes advantages and issues related to the main non-viral vectors used for ON delivery.

Retention of quinolones on human serum albumin and alpha1-acid glycoprotein HPLC columns: relationships with different scales of lipophilicity.

The retention of 10 quinolone antibacterial agents on HPLC stationary phases supporting human serum albumin (HSA) or alpha(1)-acid glycoprotein (AGP) was investigated. Among ofloxacine and flumequine, the two chiral compounds in the selected set, only the latter showed a split chromatographic peak and only on HSA but not on AGP, indicating that enantioselective specific sites play only a minor role in the retention. The retention of quinolones, which included four acidic and six zwitterionic congeners, was correlated with various lipophilicity scales: (i) theoretically calculated values, clogP, (ii) values measured at pH 7.4 by the shake-flask method, logD(7.4), and (iii) values extrapolated by retention data measured by ion-pair reversed-phase high performance liquid chromatography (RP-HPLC). We assumed that the latter values, logP(i.p.), were close to the lipophilicity of the neutral forms, logP(N), for both acidic and zwitterionic congeners. No relationship was found between retention on serum proteins and clogP values, whereas a reasonable relationship was found with logD(7.4) values, but only when the two subclasses, acidic and zwitterionic congeners, were considered separately. The relationship between retention data on serum proteins and logP(i.p.) values indicated that the affinity for serum proteins depends on the lipophilicity of the neutral forms only for logP values up to 1.5. Above this value, protein retention does not further increase, becoming almost constant. Based on both the observations above reported and the small values of the slopes of regression equations, we conclude that the interaction of the more lipophilic quinolones, mainly the zwitterions, with serum proteins is not governed uniquely by lipophilicity but also by other mechanisms, probably of electrostatic nature.

Microsphere-integrated collagen scaffolds for tissue engineering: effect of microsphere formulation and scaffold properties on protein release kinetics.

A promising approach to control the time and space distribution of signalling molecules inside tissue engineering scaffolds consists in entrapping biodegradable microspheres releasing the protein locally for long time frames. However, a rational design of microsphere-integrated scaffolds requires the knowledge of protein release profiles directly within the polymeric template. In this work, PLGA microspheres encapsulating rhodamine-labelled bovine serum albumin (BSA-Rhod) as a model protein were produced in different formulation conditions and tested for their release features in solution and in collagen and collagen/hyaluronic acid (HA) scaffolds. BSA-Rhod release profiles from single microspheres in solution and within the scaffold were assessed by using a confocal laser scanning microscopy (CLSM)-assisted method. Results suggest that the same diffusion-erosion process controls BSA-Rhod release from microspheres in solution and collagen. Nonetheless, two main factors contribute protein release within the scaffold, that is water activity in the release environment and transport properties of the protein in the gel. While microsphere formulation mainly controls the induction time necessary to activate protein release, polymer scaffold composition governs the release rate. Thus, the fine regulation of a tissue engineering construct may be obtained by an appropriate combination of microspheres and scaffolds, providing a spatial and temporal control over signalling molecule delivery.

Cyclodextrins in the production of large porous particles: development of dry powders for the sustained release of insulin to the lungs.

The aim of this work was to develop dry powders intended for insulin pulmonary delivery. To this purpose, large porous particles (LPP) made of poly(lactide-co-glycolide) (PLGA) were produced by the double emulsion-solvent evaporation technique. Hydroxypropyl-beta-cyclodextrin (HPbetaCD), also known as absorption enhancer for pulmonary protein delivery, was tested as aid excipient to optimize the aerodynamic behaviour of the microparticles. Several microsphere formulations, differing in HPbetaCD and insulin loadings, were produced and their properties compared. A contemporary release of insulin and HPbetaCD from the system can be achieved by selecting appropriate formulation conditions. HPbetaCD-containing LPP with flow properties and dimensions suitable for aerosolization and deposition in deep regions of the lung following inhalation were produced. In conclusion, the developed system turns to be of great potential for the combined delivery of the protein and the adsorption promoter in the respiratory tract.

Nanoscopic core-shell drug carriers made of amphiphilic triblock and star-diblock copolymers.

The aim of this work was to design injectable nanocarriers for drug delivery based on PCL-PEO amphiphilic block copolymers with linear ABA triblock and 4-armed (BA)(4) star-diblock architectures (A=PEO, B=PCL). The copolymers were obtained by coupling of a monofunctional -COOH end-capped PEO (M(n)=2.0kDa) with linear or 4-armed star-shaped PCL macromers bearing -OH terminal groups and were characterized by (1)H NMR spectroscopy and size exclusion chromatography. DSC and X-ray diffraction experiments showed that separate crystalline phases of PCL and PEO are present in bulk copolymers. Nanoparticles were produced by nanoprecipitation (NP) and by a new melting-sonication procedure (MS) without the use of toxic solvents, and characterized for size, polydispersity, zeta potential and core-shell structure. Nanoparticles were loaded with all-trans-retinoic acid (atRA) as a model drug and their release features assessed. Results demonstrate that both techniques allow the formation of PEO-coated nanoparticles with a hydrodynamic diameter that is larger for nanoparticles prepared by MS. atRA is released from nanoparticles at controlled rates depending on size, loading and, more important, preparation technique, being release rate faster for MS nanoparticles. Some biorelevant properties of the carrier such as complement activation were finally explored to predict their circulation time after intravenous injection. It is demonstrated that nanoparticles prepared by MS do not activate complement and are of great interest for future in vivo applications.

Cyclodextrin-containing poly(ethyleneoxide) tablets for the delivery of poorly soluble drugs: potential as buccal delivery system.

The aim of this work was to develop a tablet for the buccal delivery of the poorly soluble drug carvedilol (CAR), based on poly(ethyleneoxide) (PEO) as bioadhesive sustained-release platform and hydroxypropyl-beta-cyclodextrin (HPbetaCD) as modulator of drug release. As first, PEO tablets loaded with CAR/HPbetaCD binary systems with different dissolution properties were tested for CAR and HPbetaCD release features and compared to PEO tablets containing only CAR. When the drug was incorporated as CAR/HPbetaCD freeze-dried product, all CAR content was released from the tablet in about 10 h, displaying a constant release regimen after a transient. The effect of HPbetaCD incorporation on the release mechanism, was rationalized on the basis of the interplay of different physical phenomena: erosion and swelling of the tablet, drug dissolution, drug counter-diffusion and complex formation. In the second part of the study, the potential of HPbetaCD-containing PEO tablets as buccal delivery system for CAR was tested. It was found that the incorporation of HPbetaCD in the tablet did not alter significantly its good adhesion properties. The feasibility of buccal administration of CAR was assessed by permeation experiments on pig excised mucosa. The amount of CAR permeated from PEO tablet was higher in the case of HPbetaCD-containing tablets, the maximum value being obtained for CAR/HPbetaCD freeze-dried system. Our results demonstrate that, when the tablet is employed as transmucosal system, the role of drug dissolution enhancement in the hydrated tablet is much more relevant than in solution for increasing the delivery rate.

Drug/cyclodextrin solid systems in the design of hydrophilic matrices: a strategy to modulate drug delivery rate.

The aim of this study was to investigate how the delivery rate of erodible sustained-release hydrophilic matrices intended for the delivery of poorly soluble drugs can be optimized through the incorporation of drug/cyclodextrin binary systems. Carvedilol (CAR), a sparingly water-soluble antihypertensive drug, was selected as a model for the study. As first, we attempted to improve CAR apparent solubility by association with hydroxypropyl-beta-cyclodextrin (HPbetaCD) and then incorporated CAR/HPbetaCD binary systems in sustained-release tablets made of poly(ethyleneoxide) (PEO). Solid CAR/HPbetaCD binary systems were prepared by physical mixing, kneading, co-melting and freeze-drying methods and characterized by DSC and X-ray powder diffractometry. The amount of CAR dissolved from all the HPbetaCD-containing systems was higher than pure CAR, the co-molten and freeze-dried products showing the best dissolution performance. The incorporation of the binary systems in PEO tablets resulted in a CAR release rate much higher than tablets containing only CAR. It was found that the time necessary to achieve complete release from the tablet was linearly related to the dissolution parameters of CAR/HPbetaCD powders. In the case of co-molten and freeze-dried products, all CAR content could be released in about 12 and 10 h, respectively. Our results demonstrate that the incorporation of drug/cyclodextrin solid systems in erodable PEO matrices intended for the delivery of poorly water-soluble drugs is useful to modulate the release rate by controlling the dissolution properties of the drug inside the tablet.

Can protonated beta-blockers interact with biomembranes stronger than neutral isolipophilic compounds? A chromatographic study on three different phospholipid stationary phases (IAM-HPLC).

The chromatographic capacity factors (k') of 10 beta-adrenoceptor antagonists ("beta-blockers") were measured on three different immobilized artificial membrane-phosphatidylcholine (IAM-PC) HPLC stationary phases, namely IAM-PC-MG, IAM-PC-DD2, and IAM-PC-DD. The two former phases are made of phosphatidylcholine as found in biomembranes and differ each other in end-capping of free propylamino residues whereas the latter is made of single-chain phosphatidylcholine analogues. On IAM-PC-DD2 we found that structurally unrelated neutral compounds give a single correlation between logk' values and the respective octanol/water partition coefficients (logP), as previously observed on IAM-PC-MG phase. This was not observed on the IAM-PC-DD phase. IAM chromatography was performed at a pH of the aqueous eluent (7.0) close to the physiological pH 7.4. Retention on all IAM phases showed a biphasic pattern, being proportional to logP(N) (lipophilicity of neutral forms) for more lipophilic congeners (logP(N)>1.90), and quite constant for the others. The comparison of beta-blocker retention with that of neutral compounds on IAM-PC-MG and IAM-PC-DD2 suggests that they can interact with phospholipids as strongly or more strongly than neutral isolipophilic compounds, despite their being more than 98% in their ionized form. Therefore, we hypothesize that electrostatic interactions play a pivotal role in the interactions between beta-blockers and membrane phospholipids.

Microspheres made of poly(epsilon-caprolactone)-based amphiphilic copolymers: potential in sustained delivery of proteins.

Microspheres of amphiphilic multi-block poly(ester-ether)s (PEE)s and poly(ester-ether-amide)s (PEEA)s based on poly(epsilon-caprolactone) (PCL) were investigated as delivery systems for proteins. The interest was mainly focused on the effect of their molecular structure and composition on the overall properties of the microspheres, encapsulating bovine serum albumin (BSA) as a model protein. PEEs and PEEAs were prepared using a alpha,omega-dihydroxy-terminated PCL macromer (Mn= 2.0 kDa) as a hydrophobic component. Hydrophilic oxyethylene sequences were generated using poly(ethylene oxide)s (PEO)s of different molecular mass (Mn= 300-600 Da) in the case of PEEs, or 4,7,10-trioxa-1,13-tridecanediamine (Trioxy) and PEO150 (Mn= 150 Da) in the case of PEEAs. The copolymers showed a decrease of Tm and crystallinity values as compared with PCL. Within each class of copolymers, the bulk hydrophilicity increased with increasing the number of oxyethylene groups in the chain repeat unit. PEEAs were more hydrophilic than PEEs with a similar number of oxyethylene groups. Discrete spherical particles were prepared by both PEEs and PEEAs and their BSA encapsulation efficiency related to copolymer properties. Interestingly, the insertion of short hydrophilic segments is enough to significantly affect protein distribution inside microspheres and its release profiles, as compared to PCL microspheres. Different degradation rates and mechanisms were observed for copolymer microspheres, mainly depending on the distribution of oxyethylene units along the chain. The results highlight that a fine control over the structural parameters of amphiphilic PCL-based multi-block copolymers is a key factor for their application in the field of protein delivery.

Poly(lactide-co-glycolide) microspheres for the controlled release of oligonucleotide/polyethylenimine complexes.

In this article, microspheres able to induce the controlled release of oligonucleotide/polyethylenimine complexes are proposed. A model oligonucleotide (the oligothymidilate pdT16) was encapsulated within poly(lactide-co-glycolide) microspheres alone or associated with polyethylenimine (PEI) at different nitrogen/phospate (N/P) ratios. Microspheres were prepared by the multiple emulsion-solvent evaporation technique and characterized for morphology, diameter, encapsulation efficiency, and release kinetics. The introduction of PEI in the internal aqueous phase resulted in the formation of a soluble complex with pdT16 and in a strong increase of the oligonucleotide encapsulation efficiency. PEI affected microsphere morphology inducing the formation of very porous particles yielding to an accelerated release of pdT16. When incubated with HeLa cells, microspheres encapsulating pdT16/PEI complexes allowed both a reduction of the complex toxicity and an improvement of the intracellular penetration of the released oligonucleotide. We conclude that biodegradable microspheres encapsulating oligonucleotides/PEI complexes have a great potential as controlled release system because they allow the sustained release of an oligonucleotide carrier that crosses biological membranes and locates in nucleus.

Improving the efficacy of inhaled drugs in cystic fibrosis: challenges and emerging drug delivery strategies.

Cystic fibrosis (CF) is the most common autosomal recessive disease in Caucasians associated with early death. Although the faulty gene is expressed in epithelia throughout the body, lung disease is still responsible for most of the morbidity and mortality of CF patients. As a local delivery route, pulmonary administration represents an ideal way to treat respiratory infections, excessive inflammation and other manifestations typical of CF lung disease. Nonetheless, important determinants of the clinical outcomes of inhaled drugs are the concentration/permanence at the lungs as well as the ability of the drug to overcome local extracellular and cellular barriers. This review focuses on emerging delivery strategies used for local treatment of CF pulmonary disease. After a brief description of the disease and formulation rules dictated by CF lung barriers, it describes current and future trends in inhaled drugs for CF. The most promising advanced formulations are discussed, highlighting the advantages along with the major challenges for researchers working in this field.

Nanocarriers for topical administration of resveratrol: a comparative study.

The trans-resveratrol (t-res), a non-flavonoid polyphenol extracted from different plants, has recently earned interest for application on the skin for different applications. In this work, the potential of nanocarriers, namely transfersomes and ethanol-containing vesicles, to deliver t-res into/through the skin was investigated. Thus, transfersomes with different surfactants, namely polysorbate 80 (Tw80), sodium cholate (SC) and sodium deossicholate (SDC) and ethanol-containing vesicles with different lipid composition, namely soy phosphatidylcholine (SPC) and cholesterol (chol), encapsulating t-res were prepared and characterized. The nanocarriers had a mean diameter ranging between 83 and 116 nm with a high t-res encapsulation efficiency (≥ 70%). Moreover, cytotoxicity as well as the inhibition of production of reactive oxygen species (ROS) and lipid peroxidation, following incubation of H(2)O(2)-stimulated human keratinocyte (HaCaT) with t-res, as free or encapsulated into the nanocarriers, were investigated. Only blank nanocarriers containing Tw80 or ethanol were cytotoxic and led to increase of ROS, but this effect was not observed when using nanocarriers encapsulating t-res. Finally, permeation studies on porcine skin carried out on Franz diffusion cells, showed that only ethanol-containing vesicles based SPC were able to promote t-res permeation through the skin.

Engineering poly(ethylene oxide) buccal films with cyclodextrin: a novel role for an old excipient?

Inspired by the multiple roles cyclodextrins can play in polymeric systems, here we engineered poly(ethylene oxide) (PEO) films with (2-hydroxypropyl)-ß-cyclodextrin (CD) as multipurpose ingredient. To shed light on the potential of CD in formulating PEO buccal films for the delivery of poorly water-soluble drugs, we preliminarily assessed thermal and mechanical properties as well as wettability of films prepared at different PEO/CD ratios. PEO/CD platform containing 54% by weight of CD was chosen as the optimized composition since it matched acceptable mechanical properties, in terms of tensile strength and elasticity, with a good wettability. The platform was tested as buccal delivery system for triamcinolone acetonide (TrA), a lipophilic synthetic corticosteroid sparely water soluble. Confocal Raman imaging clearly showed that CD was homogeneously (i.e. molecularly) dispersed in PEO. Nevertheless, homogenous drug distribution in the film without TrA crystallization occurred only in the presence of CD. Finally, CD-containing PEO film placed in simulated buccal fluids provided a useful speed-up of TrA release rate while showing slower dissolution as compared to PEO film. These results, as well as compliance with quality specifications of pharmaceutical manufacturing products, strongly support the soundness of the strategy and prompt toward further applications of PEO/CD films in buccal drug delivery.

Dry powders based on PLGA nanoparticles for pulmonary delivery of antibiotics: modulation of encapsulation efficiency, release rate and lung deposition pattern by hydrophilic polymers.

Although few experimental studies have been handled so far to exploit the potential of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) in the production of dry powders for antibiotic inhalation, there has been no comprehensive study on the role played by NP composition. In this work, we try to shed light on this aspect by designing and developing a pulmonary delivery system for antibiotics, such as tobramycin (Tb), based on PLGA NPs embedded in an inert microcarrier made of lactose, referred to as nano-embedded micro-particles (NEM). At nanosize level, helper hydrophilic polymers were used to impart the desired surface, bulk and release properties to PLGA NPs prepared by a modified emulsion-solvent diffusion technique. Results showed that poly(vinyl alcohol) (PVA) and chitosan (CS) are essential to optimise the size and modulate the surface properties of Tb-loaded PLGA NPs, whereas the use of alginate (Alg) allows efficient Tb entrapment within NPs and its release up to one month. Optimized formulations display good in vitro antimicrobial activity against P. aeruginosa planktonic cells. Furthermore, spray-drying of the NPs with lactose yielded NEM with peculiar but promising flow and aerosolization properties, while preserving the peculiar NP features. Nonetheless, in vivo biodistribution studies showed that PVA-modified Alg/PLGA NPs reached the deep lung, while CS-modified NPs were found in great amounts in the upper airways, lining lung epithelial surfaces. In conclusion, PLGA NP composition appears to play a crucial role in determining not only the technological features of NPs but, once processed in the form of NEM, also their in vitro/in vivo deposition pattern.

New self-assembly nanoparticles and stealth liposomes for the delivery of zoledronic acid: a comparative study.

Zoledronic acid (ZOL) is a drug whose potent anti-cancer activity is limited by its short plasma half-life and rapid uptake and accumulation within bone. We have recently proposed new delivery systems to avoid ZOL accumulation into the bone, thus improving extra-skeletal bioavailability. In this work, we have compared the technological and anti-cancer features of either ZOL-containing self-assembly PEGylated nanoparticles (NPs) or ZOL-encapsulating PEGylated liposomes (LIPO-ZOL). ZOL-containing NPs showed superior technological characteristics in terms of mean diameter, size distribution, and ZOL encapsulation efficiency, compared to LIPO-ZOL. Moreover, the anti-cancer activity of NPs in nude mice xenografted with prostate cancer PC3 cells was higher than that one induced by LIPO-ZOL. In addition, NPs induced the complete remission of tumour xenografts and an increase of survival time higher than that one observed with LIPO-ZOL. It has also to be considered that PC3 tumour xenografts were almost completely resistant to the anti-cancer effects induced by free ZOL. Both nanotechnological products did not induce toxic effects not affecting the mice weight nor inducing deaths. Moreover, the histological examination of some vital organs such as liver, kidney and spleen did not find any changes in terms of necrotic effects or modifications in the inflammatory infiltrate. On the other hand, NPs but not LIPO-ZOL caused a statistically significant reduction of the tumour associated macrophages (TAM) in tumour xenografts. This effect was paralleled by a significant increase of both necrotic and apoptotic indexes. The effects of the NPs were also higher in terms of neo-angiogenesis inhibition. These results suggest the future preclinical development of ZOL-encapsulating NPs in the treatment of human cancer.