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.

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.

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.

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.

Engineered PLGA nano- and micro-carriers for pulmonary delivery: challenges and promises.

OBJECTIVES: The aim of this review is to summarize the current state-of-the-art in poly(lactic-co-glycolic acid) (PLGA) carriers for inhalation. It presents the rational of use, the potential and the recent advances in developing PLGA microparticles and nanoparticles for pulmonary delivery. The most promising particle engineering strategies are discussed, highlighting the advantages along with the major challenges for researchers working in this field. KEY FINDINGS: Biodegradable polymer carriers, such as PLGA particles, may permit effective protection and long-term delivery of the inhaled drug and, when adequately engineered, its efficient transport to the target. The carrier can be designed for inhalation on the basis of several strategies through the adequate combination of available particle technologies and excipients. In so doing, the properties of PLGA particles can be finely tuned at micro-size and nano-size level to fulfill specific therapeutic needs. This means not only to realize optimal in vitro/in vivo lung deposition of the formulation, which is still crucial, but also to control the fate of the drug in the lung after particle landing. SUMMARY: Although many challenges still exist, PLGA carriers may be highly beneficial and present a new scenario for patients suffering from chronic lung diseases and for pharmaceutical companies working to develop novel inhaled products.

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.

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.

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.

Resveratrol-containing gel for the treatment of acne vulgaris: a single-blind, vehicle-controlled, pilot study.

BACKGROUND: Acne vulgaris is a complex, chronic, and common skin disorder of pilosebaceous units. The major pathogenic factors involved are ductal hyperkeratinization, obstruction of sebaceous follicles resulting from abnormal keratinization of the infundibular epithelium, stimulation of sebaceous gland secretion by androgens, and microbial colonization of pilosebaceous units by Propionibacterium acnes, which promotes perifollicular inflammation. AIM: The aim of the study was to investigate the therapeutic effects of resveratrol, a natural phytoalexin produced by some spermatophytes, such as grapes and other plants, on acneic skin. METHODS: Resveratrol was incorporated in a carboxymethylcellulose-based gel. The chemical stability of resveratrol after storage at 4°C for 30 days was investigated by high-performance liquid chromatography (HPLC). The resveratrol-containing hydrogel was administered to 20 patients affected by acne vulgaris enrolled in this single-blind study. The resveratrol-containing formulation was applied daily as a solo treatment on the right side of the face for 60 days, while the hydrogel vehicle was applied to the left side of the face as a control. To objectively evaluate the results, a digital photographic database was used to collect images. The number and type of lesions were recorded for each patient, to compare the Global Acne Grading System (GAGS) score before treatment with that obtained at the end of the study. Moreover, with the innovative technique of follicular biopsy, areas of acneic skin were prepared for histopathology. The average area occupied by microcomedones at baseline was compared with that at the end of treatment. RESULTS: HPLC analysis demonstrated that resveratrol, upon incorporation into the gel, did not convert to its cis-isomer when stored at 4°C for 30 days. All patients were satisfied with the active treatment and none experienced adverse effects. Clinical evaluation showed a 53.75% mean reduction in the GAGS score on the resveratrol-treated sides of the face compared with 6.10% on the vehicle-treated sides of the face. These data were supported by histologic analysis, which showed a 66.7% mean reduction in the average area of microcomedones on the resveratrol-treated sides of the face. The comparison with the vehicle-treated side of the face (9.7% reduction) showed a clinically relevant and statistically significant decrease of lesions in areas treated with resveratrol-containing hydrogel. CONCLUSION: This pilot study showed positive results for resveratrol gel in acne, and should be considered a valid starting point for further testing of the effectiveness of this molecule in different concentrations and formulations and in a larger group of patients.

Use of cyclodextrins as solubilizing agents for simvastatin: effect of hydroxypropyl-ß-cyclodextrin on lactone/hydroxyacid aqueous equilibrium.

The chemical conversion of simvastatin from the lactone (SVL) to the hydroxyacid (SVA) form is becoming an intriguing issue associated with the pharmacological use of SVL. On this matter, recent findings suggest that SVL complexation with cyclodextrins (CDs) may be a useful strategy to affect its aqueous solubility and chemical stability. In this work, a reverse-phase high-performance liquid chromatography (RP-HPLC) method able to selectively identify and quantify SVL and SVA has been set up, validated and applied to follow SVL hydrolysis in the presence of HPßCD. The combination of stability results with simvastatin/HPßCD stability constants achieved from UV-vis measurements and solubility/dissolution studies allowed to get an insight into SVL/HPßCD, SVA/HPßCD and SVL/SVA equilibria taking place in aqueous solution. Results show that in the presence of HPßCD the aqueous SVL/SVA equilibrium is shifted versus the hydroxyacid form. UV-vis results, showing that the lactone and the open-ring form of simvastatin interact with HPßCD in a similar extent, suggest that hydrolysis occurs also on SVL/HPßCD complex, thus supporting a mode of interaction that does not involve the lactone ring. This hypothesis is strengthened by NMR analysis performed on SVA, HPßCD and their inclusion complex, which indicates that the lactone ring is not included in HPßCD hydrophobic cavity. Finally, results suggest that particular attention must be paid to SVL lactonization in aqueous solution when using CD-based formulations and in demonstrating their effective benefit for a specific therapeutic use.

Injectable thermally responsive mucoadhesive gel for sustained protein delivery.

Poloxamer thermoresponsive gels are widely explored in controlled drug delivery. Nevertheless, these gels possess inadequate mechanical properties, poor bioadhesiveness, and high permeability to water. To overcome these issues, we blended mucoadhesive hyaluronic acid (HA) with poloxamer analogs. This study aimed to investigate the features affecting the microscopic properties of the gels, which determine their macroscopic properties and capability to control/sustain protein release. Results showed that HA hampers water-poloxamer interactions, thus, strongly influencing physicochemical properties of poloxamer gels. This leads to gels with improved mechanical properties in which the diffusion kinetics of macromolecular active molecules are drastically slowed down. Poloxamer-HA gels can sustain the delivery of proteins, such as insulin, and may allow the modulation of its release kinetics by modifying HA content within the gels in the administration sites in which the active molecule release mechanism is mainly governed by its diffusion.

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.

Bioactivation of collagen matrices through sustained VEGF release from PLGA microspheres.

The success of any tissue engineering implant relies upon prompt vascularization of the cellular construct and, hence, on the ability of the scaffold to broadcast specific activation of host endothelium and guide vessel ingrowth. Vascular endothelial growth factor (VEGF) is a potent angiogenic stimulator, and if released in a controlled manner it may enhance and guide scaffold vascularization. Therefore, the aim of this work was to realize a scaffold with integrated depots able to release VEGF in a controlled rate and assess the ability of this scaffold to promote angiogenesis. VEGF-loaded poly(lactide-co-glycolide) (PLGA) microspheres were produced and included in a collagen scaffold. The release of VEGF from microspheres was tailored to be sustained over several weeks and occurred at a rate of approximately 0.6 ng/day per mg of microspheres. It was found that collagen scaffolds bioactivated with VEGF-loaded microspheres strongly enhanced endothelial cell activation and vascular sprouting both in vitro and in vivo as compared with a collagen scaffold bioactivated with free VEGF. This report demonstrates that by finely tuning VEGF release rate within a polymeric scaffold, sprouting of angiogenic vessels can be guided within the scaffolds interstices as well as broadcasted from the host tissues.

Enantioselective retention of beta-blocking agents on human serum albumin and alpha 1-acid glycoprotein HPLC columns: relationships with different scales of lipophilicity.

The enantioselective retention of thirteen beta-blockers on HPLC stationary phases supporting human serum albumin (HSA) or alpha(1)-acid glycoprotein (AGP) was investigated. Eight beta-blockers were enantiomerically resolved on the AGP column whereas only four beta-blockers were resolved on the HSA column. Moreover, interactions between beta-blockers and AGP were much stronger than those with HSA. Retention values on both HSA and AGP for less retained enantiomers related well with various lipophilicity parameters, with the best relationships found with log k(w)(IAM) values obtained on HPLC stationary phases supporting phospholipids, i.e. the so-called Immobilized Artificial Membrane (IAM). Differently from n-octanol lipophilicity values, these values encode both lipophilic. Electrostatic intermolecular recognition forces which may be involved in the interaction between ionized analytes, such as beta-blockers, and proteins. However, their effectiveness to describe non-specific interactions with serum-proteins for other classes of drugs needs further investigations. Analyses performed on AGP with eluent containing dimethyloctylamine (DMOA) as the displacer demonstrated that enantioselective sites bind to both (-)-forms and (+)-forms, but the binding to (-)-forms is stronger. The enantiomer competition to bind to a same site may be relevant from a pharmacokinetic point of view when racemic mixtures are administered. Finally, in contrast to previously reported data in the literature, we found that AGP can bind enantioselectively not only the more lipophilic congeners but also the less lipophilic ones.

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.

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.

Modulation of release rate and barrier transport of Diclofenac incorporated in hydrophilic matrices: role of cyclodextrins and implications in oral drug delivery.

The aim of this work was to investigate how the incorporation of a hydrophilic cyclodextrin (CD) inside erodible hydrophilic matrices affects drug-release behavior and transport properties through artificial and biological membranes. To this purpose, Diclofenac (Dic) was incorporated in poly(ethyleneoxide) (PEO) matrices as poorly soluble free acid (DicH) or freely water-soluble sodium salt (DicNa) in the presence or absence of hydroxypropyl-beta-cyclodextrin (HP beta CD). Preliminary experiments demonstrated that HP beta CD increased Dic apparent solubility as a function of its amount in the solution and medium pH due to complex formation. Permeation of ionized Dic through porcine buccal mucosa gave higher values of J(SS) and K(p) as compared to silicon membranes and depended on the presence of HP beta CD. Incorporation of HP beta CD in PEO tablets resulted in an increase of release rate for both forms of Dic whereas cumulative drug flux through silicon membranes and porcine buccal mucosa was increased for DicH and decreased for DicNa. An interpretation of this behavior was attempted on the basis of the presence of a transport resistance occurring inside the hydrated gel matrix as modified by the presence of CD. In conclusion, this study has demonstrated that the use of CDs in hydrophilic matrices intended for oral drug delivery should be rationalized since their modulator effect relies not only on drug-dissolution rate but also on environment where drug release occurs (aqueous medium, membrane interface).

Insulin-loaded PLGA/cyclodextrin large porous particles with improved aerosolization properties: in vivo deposition and hypoglycaemic activity after delivery to rat lungs.

The aim of the present work is to develop large porous particles (LPP) of poly (lactide-co-glycolide) (PLGA) containing insulin with optimal aerodynamic properties and to test their in vivo potential, in pulmonary delivery. Insulin-loaded LPP were fabricated by a double emulsion method by aid of hydroxypropyl-beta-cyclodextrin (HPbetaCD). Conceiving this system for the controlled release of insulin to the lungs, the aerosolization properties and the release features in simulated lung fluids of PLGA/HPbetaCD/insulin LPP were investigated in depth. The technological results show that the combination of appropriate amounts of insulin and HPbetaCD plays a crucial role to achieve PLGA/HPbetaCD/insulin LPP with the desired bulk and aerodynamic properties, that is a highly porous structure, a very low density (0.1 g/ml), an experimental mass mean aerodynamic diameter (MMAD(exp)) ranging from 4.01 to 7.00 and a fine particle fraction (FPF) estimated to be 26.9-89.6% at the different airflow rates tested (i.e. 30-90 l/min). Confocal microscopy studies, performed after administration of labeled PLGA/HPbetaCD/insulin LPP to the rat lung by means of a low-scale dry powder inhaler (DPI), suggest that particles reach alveoli and remain in situ after delivery. The pharmacological effect of PLGA/HPbetaCD/insulin LPP was confirmed by dose-response studies performed on both normoglycaemic and streptozotocin-induced diabetic rats. While insulin solutions administered via pulmonary route are unable to cause a significant hypoglycaemic effect, insulin delivered through PLGA/HPbetaCD/insulin LPP at the same doses (0.5-4.0 IU/kg) significantly reduces blood glucose level as a function of the administered dose in both animal models. The developed LPP, tested in hyperglycaemic rats at evident pathological conditions, exerts a very significant and longer hypoglycaemic effect even at insulin doses as low as 0.5 IU/kg (about 0.5 mg of PLGA/HPbetaCD/insulin LPP per rat) as compared to a insulin solution. Taken together, our results support the viability of a dry powder formulation based on biodegradable LPP for the controlled release of insulin to the lungs. In vivo data show that PLGA/HPbetaCD/insulin LPP are able to reach alveoli, release insulin, which is absorbed in its bioactive form.

A novel poloxamers/hyaluronic acid in situ forming hydrogel for drug delivery: rheological, mucoadhesive and in vitro release properties.

The influence of hyaluronic acid (HA) on the gelation properties of poloxamers blends has been studied with the aim of engineering thermosensitive and mucoadhesive polymeric platforms for drug delivery. The gelation temperature (T(gel)), viscoelastic properties and mucoadhesive force of the systems were investigated and optimised by means of rheological analyses. Poloxamers micellar diameter was evaluated by photon correlation spectroscopy (PCS). Moreover in order to explore the feasibility of these platforms for drug delivery, the optimised systems were loaded with acyclovir and its release properties studied in vitro. By formulating poloxamers/HA platforms, at specific concentrations, it was possible to obtain a thermoreversible gel with a T(gel) close to body temperature. The addition of HA did not hamper the self assembling process of poloxamers just delaying the gelation temperature of few Celsius degrees. Furthermore, HA presence led to a strong increase of the poloxamer rheological properties thus indicating possible HA interactions with micelles through secondary bonds, such as hydrogen ones, which reinforce the gel structure. These interactions could also explain PCS results which show, in systems containing HA, aggregates with hydrodynamic diameters much higher than those of poloxamer micelles. Mucoadhesion experiments showed a rheological synergism between poloxamers/HA gels and mucin dispersion which led to a change of the flow behaviour from a quite Newtonian one of the separate solutions to a pseudoplastic one of their mixture. In vitro release experiments indicated that the optimised platform was able to prolong and control acyclovir release for more than 6h.