lloprost delivered via the BREELIBTM nebulizer: a review of the clinical evidence for efficacy and safety.

Inhaled iloprost is a well-established medication to treat pulmonary arterial hypertension (PAH), a serious and potentially fatal disease of the pulmonary resistance vessels. The therapeutic administration of iloprost requires six to nine inhalations per day, due to the short biological half-life of this prostacyclin analogue. The I-NebTM AADTM, introduced in 2006, is the most commonly used nebulizer for delivering iloprost, requiring at least 6.5 min for an inhaled dose of 5 µg. In order to reduce inhalation time, a portable nebulizer based on modern-device technology was developed. The acute safety and tolerability of rapid iloprost inhalation via the BREELIBTM nebulizer was assessed in a four-part clinical trial. In this review, I describe the rationale and features of the new nebulizer, with particular emphasis on the safety and tolerability profile of iloprost inhalation via BREELIBTM observed in the first clinical studies. Meanwhile, the BREELIBTM nebulizer is approved and available for inhaled iloprost therapy combining significantly reduced inhalation time with good tolerability. This new approach will certainly improve patient convenience and compliance, possibly resulting in broader acceptance and improved efficacy of iloprost aerosol therapy in PAH.

Inhalation of repurposed drugs to treat pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a rare, but severe and life-threatening disease characterized by vasoconstriction and remodeling of the pulmonary arterioles, leading to progressive increase in pulmonary vascular resistance and ultimately to right-heart failure. In the last two decades, significant progress in treatment of PAH has been made, with currently 12 drugs approved for targeted therapy. Among these, the stable prostacyclin analogues iloprost and treprostinil have been repurposed for inhalation. The paper highlights the development of the two drugs emphasizing the rationale and advantages of the inhalative approach. Despite substantial advances in the specific, mainly vasodilatory PAH therapy, disease progression is mostly inevitable and mortality remains unacceptably high. Thus, introduction of new drugs targeting the cancer-like remodeling of the diseased pulmonary arteries is urgently needed. Inhalation offers pulmonary selectivity and will hopefully pioneer the repurposing of novel highly potent drugs for effective aerosol therapy of PAH.

The safety and pharmacokinetics of rapid iloprost aerosol delivery via the BREELIB nebulizer in pulmonary arterial hypertension.

The BREELIB nebulizer was developed for iloprost to reduce inhalation times for patients with pulmonary arterial hypertension (PAH). This multicenter, randomized, unblinded, four-part study compared inhalation time, pharmacokinetics, and acute tolerability of iloprost 5 µg at mouthpiece delivered via BREELIB versus the standard I-Neb nebulizer in 27 patients with PAH. The primary safety outcome was the proportion of patients with a maximum increase in heart rate (HR) ≥ 25% and/or a maximum decrease in systolic blood pressure ≥ 20% within 30 min after inhalation. Other safety outcomes included systolic, diastolic, and mean blood pressure, HR, oxygen saturation, and adverse events (AEs). Median inhalation times were considerably shorter with BREELIB versus I-Neb (2.6 versus 10.9 min; n = 24). Maximum iloprost plasma concentration and systemic exposure (area under the plasma concentration-time curve) were 77% and 42% higher, respectively, with BREELIB versus I-Neb. Five patients experienced a maximum systolic blood pressure decrease ≥ 20%, four with BREELIB (one mildly and transiently symptomatic), and one with I-Neb; none required medical intervention. AEs reported during the study were consistent with the known safety profile of iloprost. The BREELIB nebulizer offers reduced inhalation time, good tolerability, and may improve iloprost aerosol therapy convenience and thus compliance for patients with PAH.

Potential of the isolated lung technique for the examination of sildenafil absorption from lung-delivered poly(lactide-co-glycolide) microparticles.

Herein, we challenged the isolated lung (IL) technique to discriminate the performance of lung-delivered polymeric microparticles (MPs) having distinct drug release rates. For this purpose, sildenafil-loaded poly(lactide-co-glycolide) MPs were administered to the airspace of an IL model and the drug absorption profile was monitored. MPs (particle size of ~5µm) composed of PLGA of lower molecular weight (and glass transition temperature) manifested in the most rapid in vitro drug release (half-times ranging from <15 to ~200min). Moreover, microencapsulation resulted in a delayed sildenafil transfer over the air/perfusate barrier (half-times ranging from <5 to ~230min), where the actual ex vivo absorption profile depended on the release behavior of the utilized formulation. Finally, the obtained in vitro and ex vivo results were tested for level C, B and A correlations. The plotted data showed good agreement (R(2)>0.96) and the slopes of the resulting lines of regression (i.e., 0.80-0.85) indicated a slightly elevated in vitro drug release behavior. Overall, the IL model was able to differentiate between distinct microparticulate formulations and is, therefore, a valuable technique for early testing of potential inhalable controlled release medications.

Prolonged vasodilatory response to nanoencapsulated sildenafil in pulmonary hypertension.

Direct vasodilator delivery to the airways enables a selective therapy of pulmonary hypertension (PH). However, short-term effects of the applied medication require multiple daily inhalations. Controlled release formulations (polymeric nanomedicines) offer the potential of prolonging drug effects within the respiratory tract, thereby reducing the number of necessary inhalations. In the model of U46619-elicited PH, sildenafil and two sildenafil-loaded polymeric submicron particle formulations were evaluated for their pharmacodynamic and pharmacokinetic characteristics and acute tolerability. Lung-delivered sildenafil caused a selective dose-dependent decline of the pulmonary arterial pressure and vascular resistance. Compared to the transient pharmacodynamic effect observed for sildenafil, the same dose of nanoencapsulated sildenafil resulted in prolongation, but not augmentation, of the pulmonary vasodilatation. An extended pharmacokinetic profile was observed for nanoencapsulated sildenafil, and nanomedicines revealed no acute toxicity. The amplification of pulmonary vasodilatory response caused by nanoencapsulation of sildenafil offers an intriguing approach to ameliorate the therapy of PH. From the Clinical Editor: Pulmonary hypertension usually results in right heart failure long term. Current medical therapy includes the use of potent vasodilators such as sildenafil. In this article, the authors investigated the use of nanoencapsulated formulation for sustained delivery via inhalation route. An extended pharmacokinetic profile was seen for this nanoformulation with little side effects. It is hoped that clinical application of this would come to fruition soon.

Innovative formulations for controlled drug delivery to the lungs and the technical and toxicological challenges to overcome(.).

Inhalation of therapeutic aerosols has a long tradition and is, moreover, regarded as a safe and efficient route of drug administration to the respiratory tract. Especially, the targeting opportunities of this approach are beneficial for the treatment of numerous airway diseases. However, the rapid decay of local drug concentration and the resulting short-term duration of action of conventional medications necessitates several daily inhalations, which is clearly in conflict with a patients' convenience and compliance. Recent progress in pharmaceutical engineering has provided promising drug delivery vehicles (e.g., liposomes, nanoparticles and thermo-responsive preparations) allowing for a sustained release of the encapsulated medication at the target site. Nevertheless, aspects such as generating tailored aerosols from these formulations (including stability during aerosolization) and the choice of biocompatible excipients remain considerable challenges, which need to be addressed in order to optimize inhalation therapy. Therefore, toxicology issues raised by these novel drug delivery vehicles with respect to physicochemical and material properties and biocompatibility are described in this review. This brief overview is intended to serve as a foundation to prompt future advancement in the field of controlled drug delivery to the lungs.

Characterization of lung-delivered in-situ forming controlled release formulations.

OBJECTIVES: This study investigated the controlled drug release potential of formulations revealing temperature-induced sol-gel transition following administration to the respiratory tract. METHODS: Diverse sildenafil-containing aqueous poloxamer 407 preparations were evaluated for critical gelation temperature and rheological properties. The in-vitro drug release profiles of the in-situ forming formulations were studied in a Franz type cell, while the drug absorption characteristics were determined in an isolated lung model. Furthermore, the weight gain of isolated lungs was monitored and the bronchoalveolar lavage fluid was analysed for the total protein content. KEY FINDINGS: Poloxamer 407 solutions with concentrations of >12 wt.% revealed gelation upon temperature increase (>20°C). Compared with free sildenafil solution, sildenafil-containing polymer formulations showed a prolonged in-vitro drug release profile. Likewise, 17 and 21 wt.% of poloxamer 407 were characterized by a sustained sildenafil transfer from the lung into the perfusate. However, a 10 wt.% polymer solution displayed an immediate sildenafil absorption. Interestingly, increasing the poloxamer 407 concentration (21 and 17 vs. 10 wt.%) led to decreased organ weight gain kinetics and a lower total protein content found in the bronchoalveolar lavage fluid. CONCLUSIONS: In-situ forming controlled release hydrogels represent a viable approach for inhalative therapy.

Systematic aging of degradable nanosuspension ameliorates vibrating-mesh nebulizer performance.

CONTEXT: The process of vibrating-mesh nebulization is affected by sample physicochemical properties. Exemplary, electrolyte supplementation of diverse formulations facilitated the delivery of adequate aerosols for deep lung deposition. OBJECTIVE: This study addressed the impact of storage conditions of poly(lactide-co-glycolide) nanosuspension on aerosol properties when nebulized by the eFlow®rapid. MATERIALS AND METHODS: First, purified nanosuspensions were supplemented with electrolytes (i.e. sodium chloride, lactic and glycolic acid). Second, the degradable nanoparticles (NP) were incubated at different temperatures (i.e. 4, 22 and 36 °C) for up to two weeks. The effect of formulation supplementation and storage on aerosol characteristics was studied by laser diffraction and correlated with the sample conductivity. RESULTS AND DISCUSSION: Nebulization of purified nanosuspensions resulted in droplet diameters of >7.0 µm. However, electrolyte supplementation and storage, which led to an increase in sample conductivity (>10-20 µS/cm), were capable of providing smaller droplet diameters during vibrating-mesh nebulization (≤5.0 µm). No relevant change of NP properties (i.e. size, morphology, remaining mass and molecular weight of the employed polymer) was observed when incubated at 22 °C for two weeks. CONCLUSION: Sample aging is an alternative to electrolyte supplementation in order to ameliorate the aerosol characteristics of degradable NP formulations when nebulized by vibrating-mesh technology.

Correlation of drug release with pulmonary drug absorption profiles for nebulizable liposomal formulations.

Liposomes have attracted extensive attention as inhalative drug delivery vehicles. The preparation of tailored liposomal formulations (i.e. nebulization stability and controlled drug release profiles) would facilitate new perspectives for the treatment of pulmonary diseases. 5(6)-Carboxyfluorescein (CF)-loaded submicron liposomal formulations with varying phase transition temperatures were prepared from lipid blends in different molar ratios. Their physicochemical properties, in vitro dye release, stability to nebulization (Aeroneb Pro) and ex vivo pulmonary dye absorption and distribution characteristics were investigated. Phase transitions of liposomes were adjusted below and above body temperature (32.9-55.2 °C). The amount of CF released from liposomes in vitro correlated well with their membrane fluidity. An increase in phase transition temperature resulted in an extended dye release profile. All formulations revealed aerodynamic particle sizes of ∼4 µm with remarkable stability when nebulized by vibrating-mesh technology (percentage of encapsulated model drug ∼80%). Analogous to the release results observed in vitro, liposomal formulations revealing phase transitions above body temperature displayed an increased pulmonary CF retention in an ex vivo lung model. Consequently, an in vitro-ex vivo correlation was established, which demonstrated an excellent agreement of the dye release results with the absorption profiles observed in the biological system (R(2) ≥ 0.91). Overall, the concept of liposomal "phase transition release" is promising for controlled pulmonary drug delivery applications. The ex vivo technique enables a reliable determination of lung-specific pharmacokinetics of drug delivery vehicles, which enhances tailored carrier preparation and testing during early formulation development.

Nebulization performance of biodegradable sildenafil-loaded nanoparticles using the Aeroneb Pro: formulation aspects and nanoparticle stability to nebulization.

Polymeric nanoparticles meet the increasing interest for drug delivery applications and hold great promise to improve controlled drug delivery to the lung. Here, we present a series of investigations that were carried out to understand the impact of formulation variables on the nebulization performance of novel biodegradable sildenafil-loaded nanoparticles designed for targeted aerosol therapy of life-threatening pulmonary arterial hypertension. Narrowly distributed poly(D,L-lactide-co-glycolide) nanoparticles (size: ∼200 nm) were prepared by a solvent evaporation technique using poly(vinyl alcohol) (PVA) as stabilizer. The aerodynamic and output characteristics using the Aeroneb Pro nebulizer correlated well with the dynamic viscosity of the employed fluids for nebulization. The nebulization performance was mainly affected by the amount of employed stabilizer, rather than by the applied nanoparticle concentration. Nanoparticles revealed physical stability against forces generated during aerosolization, what is attributed to the adsorbed PVA layer around the nanoparticles. Sildenafil was successfully encapsulated into nanoparticles (encapsulation efficiency: ∼80%). Size, size distribution and sildenafil content of nanoparticles were not affected by nebulization and the in vitro drug release profile demonstrated a sustained sildenafil release over ∼120 min. The current study suggests that the prepared sildenafil-loaded nanoparticles are a promising pharmaceutical for the therapy of pulmonary arterial hypertension.

Development of a biodegradable nanoparticle platform for sildenafil: formulation optimization by factorial design analysis combined with application of charge-modified branched polyesters.

Biodegradable nanoparticles have gained tremendous attraction as carriers for controlled drug delivery to the lung. Despite numerous advances in the field, e.g. development of suitable methods for pulmonary administration of polymeric nanoparticles, a sufficient association of the therapeutic agent with the carrier system as well as drug release in a controlled fashion remain considerable challenges. Hence, this study examines the optimization of biodegradable sildenafil-loaded nanoparticle formulations intended for aerosol treatment of pulmonary hypertension. A factorial design analysis was employed to identify the important experimental factors involved in the preparation of nanoparticles by the solvent evaporation technique. The effect of tailored charge-modified branched polyesters on drug loading and in vitro drug release from nanoparticles was also evaluated. Moreover, colloidal stability of obtained nanoparticles was assessed, and stabilization of nanoparticles by lyophilization was accomplished without additional excipients. Essential experimental factors were identified and optimized to allow the preparation of nanoparticles composed of linear polyesters with a sildenafil content of ~5 wt.%. The in vitro drug release profile from these nanoparticles demonstrated a sustained release of sildenafil over ~90 min. Application of charge-modified branched polyesters enhanced the drug content in nanoparticles and drug release profile, according to the charge-density present in the employed polymer. Accordingly an increase in drug loading by a factor of ~1.4, a prolonged drug release profile from nanoparticles over ~240 min was achieved. Sildenafil release from nanoparticles made of linear and charge-modified branched polyesters was governed by a diffusion process. The obtained drug diffusion coefficients were decreased as the charge-density present in the applied polymer was increased, which promotes the strategy to improve drug loading and release rates by electrostatic interactions between polymer and drug. In addition, nanoparticles showed high colloidal stability in different media of importance for pulmonary application and were successfully stabilized by lyophilization. In conclusion, optimization of the nanoparticle preparation process together with the application of tailored polymeric materials facilitated the synthesis of promising drug carriers for sildenafil that permit a novel treatment modality for severe pulmonary hypertension.

Characterization of novel spray-dried polymeric particles for controlled pulmonary drug delivery.

Numerous studies have addressed the controlled pulmonary drug delivery properties of colloidal particles. However, only scant information on the potential of spray-drying for submicron particle preparation is available. By exploiting the advantages of spray-drying, the characteristics of submicron particles can be optimized to meet the requirements necessary for lung application. Submicron particles were prepared from organic poly(d,l-lactide-co-glycolide) (PLGA) solutions, and composite particles were spray-dried from aqueous PLGA nanosuspensions. The feed concentration, as well as the spray-mesh diameter influenced the resulting particle sizes. Nanoparticles were virtually unaffected after spray-drying. The aerodynamic characteristics of both particle species revealed aerosol particle sizes suitable for deposition in the deep lungs (≤4µm). While the entrapped drug was released within ~90min from the composite particles, extensive drug retardation (~480min) was observed for PLGA particles spray-dried from organic solution. These results suggest that nanospray-drying is a convenient method to prepare submicron, controlled drug delivery vehicles useful for pulmonary application potentially allowing access to alveolar tissue.

The potential for inhaled treprostinil in the treatment of pulmonary arterial hypertension.

Inhaled treprostinil is a safe and well-tolerated approved pharmaceutical for the treatment of pulmonary arterial hypertension. In a series of open-label studies and in the pivotal trial with 253 patients, this long-acting prostacyclin analogue demonstrated pronounced pulmonary selectivity of vasodilatory effects, improved physical capacity and excellent tolerability and safety following aerosol administration. For efficient treatment, only four daily inhalations of treprostinil are necessary compared with six to nine in iloprost aerosol therapy. This review describes in detail the development of inhaled treprostinil, starting with intravenous epoprostenol followed by inhaled iloprost and subcutaneous treprostinil, all three representing well-established and widely approved prostanoid therapies for pulmonary hypertension. In order to circumvent the drawbacks of intravenous epoprostenol, stable prostacyclin analogues with similar pharmacological properties have been investigated. In addition, alternative routes of administration have been proposed and evaluated, mainly inhaled and subcutaneous delivery. The concept of inhaled treprostinil was to combine the pulmonary selectivity of an aerosolized vasodilator with the long-acting effects of a stable prostacyclin analogue. Pulmonary arterial hypertension remains, however, a severe, life-threatening disease, in spite of the enormous progress in specific drug therapy over the last decade. Therefore, further improvement of drug therapy will be essential, with clear potential for inhaled treprostinil: a reduction of inhalation frequency and duration would markedly improve quality of life and compliance, and a longer-lasting local prostanoid effect might further enhance the efficacy of inhaled treprostinil. The advantageous pharmacological properties of treprostinil offer the opportunity to establish a convenient metered dose inhaler as a delivery system, to combine inhaled treprostinil with available or future drugs for pulmonary arterial hypertension, or to develop sustained release formulations of treprostinil suitable for inhalation based on liposomes or biodegradable nanoparticles.

Amphiphilic, low molecular weight poly(ethylene imine) derivatives with enhanced stability for efficient pulmonary gene delivery.

BACKGROUND: Poly(ethylene imine) (PEI) is a widely used transfection reagent for mammalian cells, but in vivo application of PEI 25 kDa is restricted by its toxicity. Low molecular weight (LMW) PEI is less toxic, but also less efficient than its high molecular weight equivalent, and prone to aggregation. METHOD: A set of polymers was synthesized by coupling poly(ethylene glycol) (PEG) that contained either C(16/18) -chains (Cx-EO) or butyl-poly(propylene oxide)-co-poly(ethylene glycol) (ButPP). Critical micelle concentration (CMC) was determined for copolymers. Polyplexes were characterized by DNA binding ability, polyplex size and aggregation, hemolysis, and cytotoxicity. Transfection efficiency was tested in vitro and in vivo in mouse lungs. RESULTS: Copolymers formed stable complexes with DNA, and showed enhanced complex stability in isotonic solution for at least 1 h. CMC was determined for Cx-EO-PEI 4.7 and 8.3 at 0.0019 and 0.0037 mM, respectively; membrane activity in a haemolysis assay was demonstrated for ButPP-PEI: both factors possibly enhance endosomal escape effect after PEGylation. IC(50) values of all synthesized polymers were in the range 6-33 ng/ml. Transfection efficiency of unmodified LMW-PEIs was equivalent or better than that of PEI 25 as a result of aggregation in vitro. Cells treated with polyplexes of amphiphilic polymers showed reduced transfection compared to PEI 25. After instillation in mouse lungs, highest transfection efficiency was demonstrated with Cx-EO copolymer of lowest molecular weight PEI. CONCLUSIONS: A new set of polymers with low toxicity and high stability was synthesized, which contains promising candidates for pulmonary gene transfer, as documented by in vivo experiments in mice.

Biophysical investigation of pulmonary surfactant surface properties upon contact with polymeric nanoparticles in vitro.

Nanoparticulate drug carriers have been proposed for the targeted and controlled release of pharmaceuticals to the lung. However, inhaled particles may adversely affect the biophysical properties of pulmonary surfactant. This study examines the influence of polymeric nanoparticles with distinct physicochemical properties on the adsorption and dynamic surface tension lowering properties of pulmonary surfactant. Nanoparticles had a mean size of 100 nm with narrow size distributions. Although poly(styrene) and poly(D,L-lactide-co-glycolide) nanoparticles revealed a dose-dependent influence on biophysics of pulmonary surfactant, positively-charged nanoparticles made from poly(butyl methacrylate-co-(2-dimethylaminoethyl) methacrylate-co-methyl methacrylate) showed no effect. This behavior is attributed to the differences in ζ-potential and surface hydrophobicity, which in turn involves an altered adsorption pattern of the positively charged surfactant proteins to the nanoparticles. This study suggests that polymeric nanoparticles do not substantially affect the biophysical properties of pulmonary surfactant and may be a viable drug-delivery vehicle for the inhalative treatment of respiratory diseases. FROM THE CLINICAL EDITOR: Inhaled nanoparticulate drug carriers may adversely affect the biophysical properties of pulmonary surfactant. In this study the influence of polymeric nanoparticles was characterized from this standpoint, with the conclusion that polymeric nanoparticles do not substantially affect the biophysical properties of pulmonary surfactant and may be viable drug-delivery vehicles for inhalational treatment.

Novel 'nano in nano' composites for sustained drug delivery: biodegradable nanoparticles encapsulated into nanofiber non-wovens.

Novel 'nano in nano' composites consisting of biodegradable polymer nanoparticles incorporated into polymer nanofibers may efficiently modulate drug delivery. This is shown here using a combination of model compound-loaded biodegradable nanoparticles encapsulated in electrospun fibers. The dye coumarin 6 is used as model compound for a drug in order to simulate drug release from loaded poly(lactide-co-glycolide) nanoparticles. Dye release from the nanoparticles occurs immediately in aqueous solution. Dye-loaded nanoparticles which are encapsulated by electrospun polymer nanofibers display a significantly retarded release.

Amine-modified poly(vinyl alcohol)s as non-viral vectors for siRNA delivery: effects of the degree of amine substitution on physicochemical properties and knockdown efficiency.

PURPOSE: The objective of this study was to investigate how the degree of amine substitution of amine-modified poly(vinyl alcohol) (PVA) affects complexation of siRNA, protection of siRNA against degrading enzymes, intracellular uptake and gene silencing. METHODS: A series of DEAPA-PVA polymers with increasing amine density was synthesized by modifying the hydroxyl groups in the PVA backbone with diethylamino propylamine groups using CDI chemistry. These polymers were characterized with regard to their ability to complex and protect siRNA against RNase. Finally, their potential to mediate intracellular uptake and gene silencing in SKOV-luc cells was investigated. RESULTS: A good correlation between amine density and siRNA complexation as well as protection of siRNA against RNase was found. Consisting solely of tertiary amines, this class of polymer was able to mediate efficient gene silencing when approximately 30% of the hydroxyl groups in the PVA backbone were modified with diethylamino propylamine groups. Polymers with a lower amine density (up to 23%) were inefficient in gene silencing, while increasing the amine density to 48% led to non-specific knockdown effects. CONCLUSION: DEAPA-PVA polymers were shown to mediate efficient gene silencing and offer a promising platform for further structural modifications.

Pulmonary targeting with biodegradable salbutamol-loaded nanoparticles.

BACKGROUND: Aerosol therapy using particulate drug carriers has become an increasingly attractive method to deliver therapeutic or diagnostic compounds to the lung. Polymeric nanoparticles are widely investigated carriers in nanomedicine. The targeted and controlled release of drugs from nanoparticles for pulmonary delivery, however, is a research field that has been so far rather unexploited. Therefore, the objective of this study was to compare the pulmonary absorption and distribution characteristics of salbutamol after aerosolization as solution or entrapped into novel polymeric nanoparticles in an isolated rabbit lung model (IPL). METHODS: Physicochemical properties, morphology, encapsulation efficiency, in vitro drug release, stability of nanoparticles to nebulization, as well as pulmonary drug absorption and distribution after nebulization in the IPL were investigated. RESULTS: Salbutamol-loaded poly(D,L-lactide-co-glycolide) (PLGA) and poly(vinyl sulfonate-co-vinyl alcohol)-graft-poly(D,L-lactide-co-glycolide) (VS(72)-10) nanoparticles were prepared by a modified solvent displacement technique with a mean particle size of approximately 120 nm and a polydispersity index below 0.150. VS(72)-10 nanoparticles showed a more negative zeta-potential of -54.2 +/- 3.3 mV compared to PLGA nanoparticles (-36.5 +/- 2.6 mV). Salbutamol encapsulation efficiency was 25.2 +/- 4.9% and 63.4 +/- 3.5% for PLGA and VS(72)-10 nanoparticles, respectively. After nebulization utilizing the MicroSprayer physicochemical properties of salbutamol-loaded VS(72)-10 nanoparticles were virtually unchanged, whereas nebulized salbutamol-loaded PLGA nanoparticles showed a significant increase in mean particle size and polydispersity. In vitro release studies demonstrated a sustained release of the encapsulated salbutamol from VS(72)-10 nanoparticles. In parallel, a sustained salbutamol release profile was observed after aerosol delivery of these particles to the IPL as reflected by a lower salbutamol recovery in the perfusate (40.2 +/- 5.8%) when compared to PLGA nanoparticles (55.2 +/- 9.1%) and salbutamol solution (62.8 +/- 7.1%). CONCLUSIONS: The current study suggests that inhalative delivery of biodegradable nanoparticles may be a viable approach for the treatment of respiratory diseases.

Nanocomposites of lung surfactant and biodegradable cationic nanoparticles improve transfection efficiency to lung cells.

The objective of this study was to develop highly efficient ternary nanocomposites for aerosol gene therapy consisting of a biodegradable polymer core, poly[vinyl-3-(diethylamino)propylcarbamate-co-vinyl acetate-co-vinyl alcohol]-graft-poly(d,l-lactide-co-glycolide), pDNA and a third component to alter surface properties, physicochemical characteristics and biological activity. The effects of the surface altering components lung surfactant, carboxymethyl cellulose (CMC) or poloxamer on nanocomposites were characterized with regard to size, zeta potential, cytotoxicity, biological activity and surface properties. With increasing concentrations of lung surfactant, CMC or poloxamer, sizes of nanocomposites increased. AFM nanoindentation measurements showed a significant increase in adhesion forces of nanocomposites compared to pure nanoparticles. Zeta potential values, cytotoxicity and intracellular uptake demonstrated a strong dependency on the surface altering component. While an excess of CMC led to a decreased uptake into cells due to the negative zeta potential, nanocomposites with lung surfactant displayed enhanced intracellular uptake. Transfection efficiency of nanocomposites with lung surfactant was 12-fold higher compared to pure nanoparticles and 30-fold higher compared to polyethylenimine in lung cells and could also be maintained after nebulization. Ternary nanocomposites prepared with lung surfactant proved to be a potent pulmonary gene delivery vector due to its high stability during aerosolization with a vibrating mesh nebulizer and favourable biological activity.