Stabilization of Aerosolizable Nano-carriers by Freeze-Drying

Advanced Manufacturing Methods for High-Dose Inhalable Powders

Pulmonary drug delivery is governed by three main categories of forces: interparticle forces in the powder formulation, the dispersion forces during inhalation by the device, and deposition forces in the lungs. The interaction between fine inhalable powder particles of the active ingredient is governed by various types of forces, such as capillary forces, electrostatic forces, and van der Waals forces. The different types of inter-particle interactions influence the balance between powder dispersibility and agglomerate stability. The high level of cohesion forces arising from high surface energy of very fine powder hinders powder flowability, leading to issues of agglomeration. Therefore, there is a critical need for advanced manufacturing techniques to overcome the challenges of handling and manufacture of fine cohesive particles, particularly high-dose powders for inhalation. This review will focus on the challenges facing the formulation process of very fine inhalable powder, the various types of existing particle engineering techniques for high-dose powder inhalers, and the characterization techniques employed to analyse the powder characteristics required to meet the acceptance criteria of inhalable preparations.

Polysaccharide-based formulations as potential carriers for pulmonary delivery - A review of their properties and fates

Polysaccharides can be elite carriers for therapeutic molecules due to their versatility and low probability to trigger toxicity and immunogenic responses. Local and systemic therapies can be achieved through particle pulmonary delivery, a promising non-invasive alternative. Successful pulmonary delivery requires particles with appropriate flowability to reach alveoli and avoid premature clearance mechanisms. Polysaccharides can form micro-, nano-in-micro-, and large porous particles, aerogels, and hydrogels. Herein, the characteristics of polysaccharides used in drug formulations for pulmonary delivery are reviewed, providing insights into structure-function relationships. Charged polysaccharides can confer mucoadhesion, whereas the ability for specific sugar recognition may confer targeting capacity for alveolar macrophages. The method of particle preparation must be chosen considering the properties of the components and the delivery device to be utilized. The fate of polysaccharide-based carriers is dependent on enzyme-triggered hydrolytic and/or oxidative mechanisms, allowing their complete degradation and elimination through urine or reutilization of released monosaccharides.

State-of-the-Art Review of The Application and Development of Various Methods of Aerosol Therapy

Aerosol therapy is a rapidly developing field of science. Due to a number of advantages, the administration of drugs to the body with the use of aerosol therapy is becoming more and more popular. Spraying drugs into the patient's lungs has a significant advantage over other methods of administering drugs to the body, including injection and oral methods. In order to conduct proper and effective aerosol therapy, it is necessary to become familiar with the basic principles and applications of aerosol therapy under various conditions. The effectiveness of inhalation depends on many factors, but most of all on: the physicochemical properties of the sprayed system, the design of the medical inhaler and its correct application, the dynamics of inhalation (i.e. the frequency of breathing and the volume of inhaled air). It is worth emphasizing that respiratory system diseases are one of the most frequently occurring and fastest growing diseases in the world. Accordingly, in recent years, a significant increase in the number of new spraying devices and pharmaceutical drugs for spraying has appeared on the market. It should also be remembered that the process of spraying a liquid is a complicated and complex process, and its efficiency is very often characterized by the use of micro- and macro parameters (including average droplet diameters or the spectrum of droplet diameter distribution). In order to determine the effectiveness of the atomization process and in the delivery of drugs to the patient's respiratory tract, the analysis of the size of the generated aerosol droplets is most often performed. Based on the proposed literature review, it has been shown that many papers dealt with the issues related to aerosol therapy, the selection of an appropriate spraying device, the possibility of modifying the spraying devices in order to increase the effectiveness of inhalation, and the possibility of occurrence of certain discrepancies resulting from the use of various measurement methods to determine the characteristics of the generated aerosol. The literature review presented in the paper was prepared in order to better understand the spraying process. Moreover, it can be helpful in choosing the right medical inhaler for a given liquid with specific rheological properties. The experimental data contained in this study are of great cognitive importance and may be of interest to entities involved in pharmaceutical product engineering (in particular in the case of the production of drugs containing liquids with complex rheological properties).

Alendronate sodium-polymeric nanoparticles display low toxicity in gastric mucosal of rats and Ofcol II cells

The use of bisphosphonates constitutes the gold-standard therapy for the control and treatment of bone diseases. However, its long-term use may lead to gastric problems, which limits the treatment. Thus, this study aimed to formulate a nanostructured system with biodegradable polymers for the controlled release of alendronate sodium. The nanoparticles were characterized, and its gastric toxicity was investigated in rats. The synthesis process proved to be effective for encapsulating alendronate sodium, exhibiting nanoparticles with an average size of 51.02 nm and 98.5% of alendronate sodium incorporation. The release tests demonstrated a controlled release of the drug in 420 min, while the morphological analyzes showed spherical shapes and no apparent roughness. The biological tests demonstrated that the alendronate sodium nanoformulation reversed the gastric lesions, maintaining the normal levels of malondialdehyde and myeloperoxidase. Also, the encapsulated alendronate sodium showed no toxicity in murine osteoblastic cells, even at high concentrations.

The function and performance of aqueous aerosol devices for inhalation therapy

OBJECTIVES

In this review paper, we explore the interaction between the functioning mechanism of different nebulizers and the physicochemical properties of the formulations for several types of devices, namely jet, ultrasonic and vibrating-mesh nebulizers; colliding and extruded jets; electrohydrodynamic mechanism; surface acoustic wave microfluidic atomization; and capillary aerosol generation.

KEY FINDINGS

Nebulization is the transformation of bulk liquids into droplets. For inhalation therapy, nebulizers are widely used to aerosolize aqueous systems, such as solutions and suspensions. The interaction between the functioning mechanism of different nebulizers and the physicochemical properties of the formulations plays a significant role in the performance of aerosol generation appropriate for pulmonary delivery. Certain types of nebulizers have consistently presented temperature increase during the nebulization event. Therefore, careful consideration should be given when evaluating thermo-labile drugs, such as protein therapeutics. We also present the general approaches for characterization of nebulizer formulations.

SUMMARY

In conclusion, the interplay between the dosage form (i.e. aqueous systems) and the specific type of device for aerosol generation determines the effectiveness of drug delivery in nebulization therapies, thus requiring extensive understanding and characterization.

Design and characterization of a new peptide vector for short interfering RNA delivery

RNA interference holds tremendous potential as one of the most powerful therapeutic strategies. However, the properties of short interfering RNA (siRNA), such as hydrophilicity, negative charge, and instability in serum have limited its applications; therefore, significant efforts have been undertaken to improve its cellular uptake. Cell penetrating peptides have been utilized to deliver various biologically active molecules, such as proteins, liposomes, nanoparticles, peptide nucleic acids, and recently small interfering RNAs. Here, we introduce a new cell penetrating peptide GL1(Ac-GLWRAWLWKAFLASNWRRLLRLLR-NH2) to improve the intracellular uptake of siRNA. This peptide consists of four tryptophan residues that facilitated its binding with the cell membrane, five arginine residues and one lysine residue which are positively charged at physiological pH, which induced the formation of peptide-siRNA complexes and enhanced the affinity of the peptide and cell membrane. Moreover, GL1 adopted helical secondary structure due to the altered distribution of polar and nonpolar residues in the sequence. In this study, we investigated the effect of peptide/siRNA molar ratio on the particle size, surface charge, secondary structure, and uptake efficiency. The results showed that GL1 formed stable complexes with siRNA mainly through electrostatic interaction and hydrophobic interaction, and the complexes displayed a spherical shape with the size of ~100 nm and positive surface charge. Utilizing the techniques of fluorescence microscopy and flow cytometry, the intracellular localization of Cy3-labeled GAPDH siRNA was visualized and the cellular uptake was quantified. It is worth noting that in the serum free environment, compared to Lipofectamine 2000, GL1 achieved higher cellular uptake of siRNA (~95%); in the presence of serum, GL1 retained the same level of siRNA cellular uptake (~84%) as Lipofectamine 2000. In addition, the viability of cells treated by GL1 in all studied molar ratios was >85%, which was significantly higher than that treated by Lipofectamine 2000 (~70%). Taken together, the peptide GL1 demonstrated promise as a siRNA delivery system.

Aerosol-based fabrication of modified chitosans and their application for gene transfection

Modified chitosan nanoparticles were conveniently obtained by a one-step aerosol method, and their potential for gene transfection was investigated. Droplets containing modified chitosans were formed by collison atomization, dried to form solid particles, and collected and studied for potential use as nanocarriers. Modified chitosans consisted of a chitosan backbone and an additional component [covalently attached cholesterol; or blends with poly(l-lysine) (PLL), polyethyleneimine (PEI), or poly(ethylene glycol) (PEG)]. Agarose gel retardation assays confirmed that modified chitosans could associate with plasmid DNA. Even though the average cell viability of cholesterol-chitosan (Ch-Cs) showed a slightly higher cytotoxicity (∼90% viability) than that for unmodified chitosan (Cs, ∼95%), transfection (>7.5 × 10(5) in relative light units (RLU) mg(-1)) was more effective than it was for Cs (∼7.6 × 10(4) RLU mg(-1)). The blending of PEI with Cs (i.e., a Cs/PEI) to produce transfection complexes enhanced the transfection efficiency (∼1.3 × 10(6) RLU mg(-1)) more than did the addition of PLL (i.e., a Cs/PLL, ∼9.3 × 10(5) RLU mg(-1)); however, it also resulted in higher cytotoxicity (∼86% viability for Cs/PEI vs ∼94% for Cs/PLL). The average cell viability (∼92%) and transfection efficiency (∼1.9 × 10(6) RLU mg(-1)) were complemented further by addition of PEG in Cs/PEI complexes (i.e., a Cs/PEI-PEG). This work concludes that gene transfection of Cs can be significantly enhanced by adding cationic polymers during aerosol fabrication without wet chemical modification processes of Cs.

Polymer nanoparticle-based controlled pulmonary drug delivery

The development of novel formulations for controlled pulmonary drug delivery purposes has gained remarkable interest in medicine. Although nanomedicine represents attractive concepts for the treatment of numerous systemic diseases, scant information is available on the controlled drug release characteristics of colloidal formulations following lung administration, which might be attributed to the lack of methods to follow their absorption and distribution behavior in the pulmonary environment.In this chapter, we describe the methods of preparation and characterization of drug-loaded polymeric nanoparticles prepared from biodegradable charge-modified branched polyesters, aerosolization of the nanosuspensions using a vibrating-mesh nebulizer, and evaluation of the pulmonary pharmacokinetics (i.e., absorption and distribution characteristics) of the nanoscale drug delivery vehicles following aerosol delivery to the airspace of an isolated lung model. The disclosed methodology may contribute to the design of advanced colloids for the treatment of respiratory disorders.

Processing/formulation parameters determining dispersity of chitosan particles: an ANNs study

Although a great number of studies may be found in literature about the parameters affecting the size of chitosan nanoparticles, no systematic work so far has detailed the factors affecting the polydispersity of chitosan as an important factor determining the quality of many preparations. Herein, using artificial neural networks (ANNs), four independent variables, namely, pH and concentration of chitosan solution as well as time and amplitude of sonication of the solution were studied to determine their influence on the polydispersity of solution. We found that in an ultrasound prepared nanodispersion of chitosan, all the four input parameters have reverse but non-linear relation with the polydispersity of the nanoparticles.

Development and characterization of phospholipid-stabilized submicron aqueous dispersions of coenzyme Q₁₀ presenting continuous vibrating-mesh nebulization performance

Coenzyme Q₁₀ (CoQ₁₀) is a poorly-water soluble compound that is being investigated for the treatment of carcinomas. The aim of this research was to develop a suitable formulation for pulmonary delivery of this anticancer agent. An appropriate selection of excipients (phospholipids) and a suitable device (Aeroneb Pro® vibrating-mesh nebulizer) were selected initially after reviewing the literature. After characterization of the bulk drug, a feasible manufacturing process was selected to obtain small particle size dispersions of CoQ₁₀. Following selection of an appropriate process, the parameters affecting drug particle size were studied. Using LD and gravimetrical analysis, nebulization was evaluated to assess the performance of the inhalation system triad: drug-excipients-device. CoQ₁₀ powder studied was crystalline with a melting point approximately at 51 °C and with a particle size of 30 µm. Microfluidization was found to be a suitable method to prepare submicron drug particles in aqueous dispersions. Increasing microfluidization processing to more than 50 passes did not provide further particle downsizing for both soya phosphatidylcholine (lecithin) and dipalmitoyl phosphatidylcholine (DPPC) dispersions of CoQ₁₀, presenting Z-average values of approximately 130 and 70 nm, respectively. Nebulization performance of lecithin-stabilized CoQ₁₀ dispersions varied according to number of passes in the microfluidizer. Formulations processed with 10 passes presented steadier nebulization over time and different rheological behavior compared to those processed with 30 or 50 passes. In conclusion, aqueous dispersions of CoQ₁₀ were adequately produced using a microfluidizer with characteristics that were suitable for pulmonary delivery with an Aeroneb Pro® nebulizer. Furthermore, the rheology of these dispersions appeared to play a significant role in the aerosol generation from the active vibrating-mesh nebulizer used.

Experiment on the feasibility of using modified gelatin nanoparticles as insulin pulmonary administration system for diabetes therapy

Polymeric nanoparticles are widely used as targeted carriers for biomacromolecules. In this paper, modified gelatin nanoparticles were prepared and their feasibility as insulin pulmonary administration system was investigated. D: ,L: -glyceraldehyde and poloxamer 188 were used for gelatin nanoparticle preparation. Novel water-in-water emulsion technique was used to prepare insulin-loaded nanoparticles. Morphological examination of insulin-loaded nanoparticles was carried out using scanning electron microscopy (SEM). Intratracheal instillation of insulin-loaded nanoparticles was performed to evaluate animal hypoglycemic effect. With fluorescence labeling of insulin, alveolar deposition and absorption of insulin-loaded nanoparticles were investigated. Histological changes in the lung were also observed to evaluate the safety. From the micromorphology observation, insulin-loaded nanoparticles under gelatin-poloxamer 188 ratio at 1:1 showed smooth and uniform surface, with average particle size 250 nm and Zeta potential -21.1 mV. From animal experiment, insulin-loaded nanoparticles under gelatin-poloxamer 188 ratio at 1:1 promoted insulin pulmonary absorption effectively and showed good relative pharmacological bioavailability. Proved by alveolar deposition result, FITC-insulin-loaded nanoparticle group was characterized by an acute and rapid hypoglycemic effect. In addition, nanoparticles could guarantee the safety of lung by reducing insulin deposition in lung. A transient weak inflammatory response was observed at 1 day after administration. With good physical characterization, high bioavailability, fast and stable hypoglycemic effect, insulin-loaded nanoparticles might be developed as a novel insulin pulmonary system for diabetes therapy.

Following the concentration of polymeric nanoparticles during nebulization

PURPOSE

Nebulization represents one strategy to achieve pulmonary deposition of biodegradable nanoparticles. Besides stability as a key requirement to maintain functionality, the output of nanoparticles from the nebulizer needs to be considered to facilitate an efficient pulmonary therapy.

METHODS

Formulations nebulized by air-jet and vibrating-membrane technology were analyzed for their aerodynamic characteristics by laser diffraction. The nebulization stability of poly(D,L-lactide-co-glycolide) nanoparticles was assessed by dynamic light scattering. Moreover, several methods were employed to account for the shift in solute and NP reservoir concentration during nebulization.

RESULTS

Regardless of the formulation or nebulizer used generated aerosols all showed aerodynamic characteristics suitable for deep lung deposition. However, nanoparticles were prone to aggregation and concentrated during air-jet nebulization. The particle concentration effect was significantly pronounced in comparison to molecular solutes under the same nebulization conditions, due to nanoparticle aggregation and subsequent particle remainder in the reservoir. In contrast, vibrating-membrane technology did not affect nanoparticle integrity and reservoir concentration during nebulization, as the unaffected submicron particles passed through the tapered holes of the actuated plate.

CONCLUSIONS

Aggregation and concentration effects during air-jet nebulization emphasize that nanosuspensions should preferably be delivered with a suitable vibrating-membrane device in order to ensure an effective pulmonary application.

Lyophilised ready-to-use formulations of PEG-PCL-PEI nano-carriers for siRNA delivery

The purpose of the present study was to transfer aqueous PEG-PCL-PEI nano-suspensions into dry ready-to-use formulations, suitable for delivery of siRNA. Therefore, freshly prepared nano-suspensions were lyophilised with glucose as lyoprotectant. Firstly, the required glucose concentration for sufficient stabilisation of unloaded carriers was determined via dynamic light scattering. Morphology of fresh and rehydrated carriers was visualised by cryogenic scanning electron microscopy. Subsequently, the feasibility of siRNA loading before and after lyophilisation was investigated. For both strategies complex diameter and in vitro transfection efficiency were determined and correlated to freshly prepared samples. Hydrodynamic diameter (95.2 ± 1.4 nm) and size distribution (0.132 ± 0.019) of unloaded nano-suspension were restored after rehydration by addition of ≥ 1.5% of glucose before lyophilisation. Moreover, after loading of rehydrated carriers with siRNA, no significant difference in complex size was observed as compared to freshly prepared ones. Stabilisation of pre-formed carrier/siRNA complexes during lyophilisation is feasible at elevated N/P (e.g. 20) and glucose concentrations above 5%. As determined via real-time-PCR, lyophilised samples were as active as freshly prepared ones regarding transfection efficiency. In conclusion, lyophilisation is an effective technique to produce physically stable PEG-PCL-PEI formulations. These general findings may be applicable to further particulate gene delivery systems to shelf ready-to-use formulations.

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.

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.