Effervescent dry powder for respiratory drug delivery.

The objective of this work was to develop a new type of respiratory drug delivery carrier particle that incorporates an active release mechanism. Spray drying was used to manufacture inhalable powders containing polybutylcyanoacrylate nanoparticles and ciprofloxacin as model substances for pulmonary delivery. The carrier particles incorporated effervescent technology, thereby adding an active release mechanism to their pulmonary route of administration. Effervescent activity of the carrier particles was observed when the carrier particles were exposed to humidity. Gas bubbles caused by the effervescent reaction were visualized by confocal laser scanning microscopy. The images showed that nanoparticles were distributed throughout the gas bubble. For the effervescent formulation the average mass median aerodynamic diameter (MMAD) was 2.17 microm+/-0.42, fine particle fraction (FPF(<=5.6 microm)) was 46.47%+/-15 and the GSD was 2.00+/-0.06. The results also showed that the effervescent carrier particles released 56+/-8% ciprofloxacin into solution compared with 32+/-3% when lactose carrier particles were used. The mean nanoparticle size did not significantly change upon release when the nanoparticles were incorporated into an effervescent formulation. However, the mean size significantly increased upon release when only lactose was used as carrier particle matrix. In conclusion, effervescent carrier particles can be synthesized with an adequate particle size for deep lung deposition. This opens the door for future research to explore this technology for delivery of a large range of substances to the lungs with possible improved release compared to conventional carrier particles.     

Aerosol Delivery of Nanoparticles in Uniform Mannitol Carriers Formulated by Ultrasonic Spray Freeze Drying

Purpose

While most examples of nanoparticle therapeutics have involved parenteral or IV administration, pulmonary delivery is an attractive alternative, especially to target and treat local infections and diseases of the lungs. We describe a successful dry powder formulation which is capable of delivering nanoparticles to the lungs with good aerosolization properties, high loadings of nanoparticles, and limited irreversible aggregation.

Methods

Aerosolizable mannitol carrier particles that encapsulate nanoparticles with dense PEG coatings were prepared by a combination of ultrasonic atomization and spray freeze drying. This process was contrasted to particle formation by conventional spray drying.

Results

Spray freeze drying a solution of nanoparticles and mannitol (2 wt% solids) resulted in particles with an average diameter of 21?±?1.7 μm, regardless of the fraction of nanoparticles loaded (0–50% of total solids). Spray freeze dried (SFD) powders with a 50% nanoparticle loading had a fine particle fraction (FPF) of 60%. After formulation in a mannitol matrix, nanoparticles redispersed in water to < 1 μm with hand agitation and to < 250 nm with the aid of sonication. Powder production by spray drying was less successful, with low powder yields and extensive, irreversible aggregation of nanoparticles evident upon rehydration.

Conclusions

This study reveals the unique advantages of processing by ultrasonic spray freeze drying to produce aerosol dry powders with controlled properties for the delivery of therapeutic nanoparticles to the lungs.     

Enhanced Dispersibility and Deposition of Spray-dried Powders for Pulmonary Gene Therapy

Spray-drying represents a viable alternative to freeze-drying for preparing dry powder dispersions for delivering macromolecules to the lung. The dispersibility of spray-dried powders is limited however, and needs to be enhanced to improve lung deposition and subsequent biological activity. In this study, we investigate the utility of leucine as a dry powder dispersibility enhancer when added prior to spray-drying a model non-viral gene therapy formulation (lipid:polycation:pDNA, LPD). Freeze-dried lactose–LPD, spray-dried lactose–LPD and spray-dried leucine–lactose–LPD powders were prepared. Scanning electron microscopy showed that leucine increased the surface roughness of spray-dried lactose particles. Particle size analysis revealed that leucine-containing spray-dried powders were unimodally dispersed with a mean particle diameter of 3.12 μm. Both gel electrophoresis and in vitro cell (A549) transfection showed that leucine may compromise the integrity and biological functionality of the gene therapy vector. The deposition of the leucine containing powder was however significantly enhanced as evidenced by an increase in gene expression mediated by dry powder collected at lower stages of a multistage liquid impinger (MSLI). Further studies are required to determine the potential of leucine as a ubiquitous dispersibility enhancer for a variety of pulmonary formulations.     

The development of a novel dry powder inhaler

A novel active and multi-dose dry powder inhaler (DPI) was developed and evaluated to deliver a small quantity (100-500 μg) of pure drug without any excipient. This dry powder inhaler utilized two compressed air flows to dispense and deliver drug powder: the primary flow aerosolizes the drug powder from its pocket and the secondary flow further disperses the aerosol. In vitro tests by Anderson Cascade Impactor (ACI) indicated that the fine particle fraction (FPF) (<4.7 μm) of drug delivery could reach over a range of 50-70% (w/w). Emitted dose tests showed that delivery efficiency was above 85% and its relative standard deviation (RSD) was under 10%. Confocal microscopy was used to confirm the deposition of fluorescently labeled spray-dried powder in rabbit lungs. Also, a chromatographic method was used to quantify drug deposition. The results of animal tests showed that 57% of aerosol deposited in the rabbit lung and 24% deposited in its trachea. All the results implied that this novel active dry powder inhaler could efficiently deliver a small quantity of fine drug particles into the lung with quite high fine particle fraction.     

Enhanced dispersibility and deposition of spray-dried powders for pulmonary gene therapy

Spray-drying represents a viable alternative to freeze-drying for preparing dry powder dispersions for delivering macromolecules to the lung. The dispersibility of spray-dried powders is limited however, and needs to be enhanced to improve lung deposition and subsequent biological activity. In this study, we investigate the utility of leucine as a dry powder dispersibility enhancer when added prior to spray-drying a model non-viral gene therapy formulation (lipid:polycation:pDNA, LPD). Freeze-dried lactose-LPD, spray-dried lactose-LPD and spray-dried leucine-lactose-LPD powders were prepared. Scanning electron microscopy showed that leucine increased the surface roughness of spray-dried lactose particles. Particle size analysis revealed that leucine-containing spray-dried powders were unimodally dispersed with a mean particle diameter of 3.12 microm. Both gel electrophoresis and in vitro cell (A549) transfection showed that leucine may compromise the integrity and biological functionality of the gene therapy vector. The deposition of the leucine containing powder was however significantly enhanced as evidenced by an increase in gene expression mediated by dry powder collected at lower stages of a multistage liquid impinger (MSLI). Further studies are required to determine the potential of leucine as a ubiquitous dispersibility enhancer for a variety of pulmonary formulations.     

Lactose as a carrier in dry powder formulations: the influence of surface characteristics on drug delivery.

The aim of the study was to investigate the interdependence of carrier particle size, surface treatment of the carrier, and inclusion of fines on the drug delivery from dry power inhaler formulations. Two size fractions (< 63 and 63-90 microm) of alpha-lactose monohydrate were subjected to treatment with 95% (v/v) ethanol to introduce small asperities or cavities onto the otherwise smooth surface without substantially changing the particle shape. After blending with albuterol sulfate [ALB; volume median diameter (VMD), 1.9 microm; geometric standard deviation (GSD), 1.5], the solvent-treated lactose produced a fine particle fraction (FPF; < 6.18 microm) and dispersibility of the drug that was significantly (ANOVA p < 0.01) lower than that which resulted from formulations containing untreated lactose of a similar size fraction, after aerosolization at 60 L min(-1) via a Rotahaler. The two size fractions of the treated lactose resulted in similar deposition profiles of ALB. The effects of such surface asperities or cavities of lactose were offset by introducing a small amount (5% w/w) of smaller-sized lactose (5-10 microm) to the powder formulations. The fine lactose increased the FPF and dispersibility of ALB to such a level that all lactose batches, regardless of particle size or whether solvent treated, produced a similar fraction of aerosolized ALB. The inclusion of recrystallized needle lactose (5-15 microm) was superior to micronized lactose in improving the aerosolization of ALB. The findings of this study indicate that the presence and characteristics of the finer fraction of lactose carrier particles dominate over the particle size and surface smoothness of the carrier particles in determining dispersion and deaggregation of drugs from dry powder formulations for inhalation.     

A comparative study of a range of polymeric microspheres as potential carriers for the inhalation of proteins

The aim of this study was to compare protein-loaded inhalable microparticles manufactured using a range of biocompatible polymers including hydroxypropyl cellulose (HPC), chitosan, hyaluronic acid, alginate, gelatin, ovalbumin and poly(lactide-co-glycolide) (PLGA). Spray-drying was used to prepare microparticles containing bovine serum albumin labeled with fluorescein isothiocyanate (BSA-FITC). Particles of respirable size and high protein loading were obtained. No evidence of BSA degradation was seen from PAGE analysis. The microparticles were mixed with mannitol as a carrier and powder aerosolization was assessed with a multi-dose dry powder inhaler (DPI) using a multi-stage cascade impactor. The mass median aerodynamic diameter (MMAD) ranged between 2.9 and 4.7 microm. Potential polymer toxicity in the lungs was compared by impinging the particles on Calu-3 monolayers and assessing the cytotoxicity, induction of cytokine release, changes in transepithelial permeability and electrical resistance. No toxic effects were observed with most of the polymers though some evidence of compromised cell monolayer integrity was seen for PLGA and ovalbumin. PLGA and gelatin microparticles caused a significant increase in IL-8 release. Of the polymers studied, PLGA showed the greatest toxicity. Certain polymers showed particular promise for specific protein delivery needs in the lungs, such as HPC to improve flow properties, sodium hyaluronate for controlled release, and chitosan and ovalbumin for systemic delivery.     

Drug release study of large hollow nanoparticulate aggregates carrier particles for pulmonary delivery

The aim of the present work is to examine the viability of using large hollow nanoparticulate aggregates as the therapeutic carrier particles in dry powder inhaler delivery of nanoparticulate drugs. The large hollow carrier particles are manufactured by spray drying of nanoparticulate suspensions of biocompatible acrylic polymer with loaded drugs. The size and concentration of the nanoparticles, as well as the phospholipids inclusion, have been known to influence the resulting morphology (i.e. size and degree of hollowness) of the spray-dried carrier particles. The effects of the resulting morphology of the carrier particles on the drug release rate are therefore investigated by varying the above three variables. The results of the drug release study are presented using aspirin and salbutamol sulfate as the model drugs with a varying degree of water solubility. The results indicate that the drug release rate is governed by the degree of hollowness of the carrier particles, and to a lesser extent by the nanoparticles size, as a result of the variation in the drug loading capacity of nanoparticles of different sizes.     

Theophylline particle design using chitosan by the spray drying

Solid dispersions of theophylline with chitosan as a carrier were prepared using a spray-drying method. Chitosan dissolved in an acid solution forms a gel, but it does not dissolve in an alkaline solution. Therefore, drugs which form composite particles with chitosan would gradually be released in an acid solution, and are expected to have considerably sustained release in an alkaline solution. In this study, we aimed to apply this ability to sustained release pharmaceutics.

In this study, we used theophylline as a model drug and chitosan as a carrier. Mixtures of chitosan and the drug in prescribed ratios were dissolved in an acid solution.

The physicochemical properties of the solid dispersions obtained were investigated by powder X-ray diffraction, differential scanning calorimetry, and dissolution rate analyses, with a view to clarify the effect of crystallinity on the dissolution rate. Furthermore, the interaction between the drug and the carrier was investigated by FT-IR analysis.

The powder X-ray diffraction intensity of the drug in the spray-dried samples decreased with an increase in chitosan contents, which also caused changes from crystalline to amorphous forms. These results indicated that the system formed a solid dispersion. The dissolution profiles of the drug from the physical mixtures and solid dispersions were almost the same at pH 1.2. However, at pH 6.8, the release from the solid dispersions was sustained more than that from the physical mixtures. The FT-IR spectroscopy for the theophylline solid dispersions suggested that the carbonyl group of theophylline and the amino group of chitosan formed a hydrogen bond.

Mass median aerodynamic diameter (MMAD) was measured by using a cascade impactor to evaluate the possibility of solid dispersions as dry powder inhalations. The MMAD of the spray-dried theophylline-chitosan systems were 4.5–5.0 μm. The results suggested that the spray-drying method is usefull to produce dry powders for inhalation.     

Effect of separation characteristics between salbutamol sulfate (SS) particles and model carrier excipients on dry powder for inhalation]

Most often dry powder for inhalation are formulated as ordered mixtures of a carrier excipient and a micronized drug substance. In the present study, model powder blends were prepared from a mixture of lactose alpha-monohydrate, micro-crystalline cellulose pellets or synthesized sugar as carrier particles, and micronized salbutamol sulfate (SS). These ordered mixtures were aerosolized by the multidose JAGO dry powder inhaler (DPI) and their in vitro deposition properties were evaluated by a twin impinger (TI). The separation force between SS particles and carrier particles was investigated by the centrifuge method. In addition, the use of the air jet sieve (AJS) method was investigated to assess the separation behavior of drug particles from carrier excipient. Powder blends were sieved through a 325 mesh wire screen of an air jet sieve at an air pressure of 1500 Pa. The amount of drug deposited at the carrier surface was analysed before and after the sieving to calculate the percentage of the drug retained. A relationship was found between in vitro deposition properties (fine particle fraction, FPF) and the separation characteristics obtained by the centrifuge method and by the AJS method. The AJS method might be a suitable alternative for evaluating separation of a drug particle from carrier particles and hence can be used for the formulation screening of the dry powder inhalation.     

The influence of amino acids on aztreonam spray-dried powders for inhalation

The dry powder inhalation of antibiotics for the treatment of lung infections has attracted drastically increasing attention as it offers rapid local therapy at lower doses and minimal side effects. In this study, aztreonam (AZT) was used as the model antibiotic and spray-dried to prepare powders for inhalation. Amino acids of glycine (GLY), histidine (HIS) and leucine (LEU) were used as excipients to modify the spray-dried particles. It was demonstrated that the GLY-AZT spray-dried powders formed huge agglomerates with the size of 144.51 µm, which made it very difficult to be delivered to the lungs (FPF: 0.29% w/w only). In comparison with the AZT spray-dried powders, HIS-modified spray-dried powders showed increased compressibility, indicating larger distance and less cohesion between particles; while the LEU-modified spray-dried particles showed a hollow structure with significantly decreased densities. The fine particle fraction for HIS- and LEU-modified powders was 51.4% w/w and 61.7% w/w, respectively, and both were significantly increased (one-way ANOVA, Duncan's test, P <0.05) compared to that of AZT spray-dried powders (45.4% w/w), showing a great potential to be applied in clinic.     

可溶性载体对左旋硫酸沙丁胺醇胶囊型粉雾剂的体外影响

目的：通过对左旋硫酸沙丁胺醇胶囊型粉雾剂可溶性载体的考察,筛选出最佳的载体材料及制备工艺。方法：对于可溶性载体辅料,采用纳米磨与喷雾干燥仪分别制备药物、辅料的颗粒物,测定颗粒的理化性质及肺部有效沉积率。结果：喷雾干燥仪制备后,载体粒径在25.35~52.94 μm之间,其中乳糖外观圆整,粒径为25.35 μm,乳糖的休止角为33.20°,乳糖的含水量最低为0.99%,压缩度为17.68%,有效沉积率为14.21%,符合药典对粉雾剂的要求。结论：喷雾制备的乳糖,其粉体性能良好,是适合左旋沙丁胺醇粉雾剂的载体材料。     

The use of different grades of lactose as a carrier for aerosolised salbutamol sulphate

Five different grades of lactose namely, anhydrous lactose, medium lactose, regular lactose, lactose crystals and foremost lactose were fractionated under similar conditions to obtain a size range of 63-90 microm and were characterised using laser diffraction and time-of-flight particle sizing techniques, scanning electron microscopy, optical microscopy image analysis, thermal gravimetric analysis and differential scanning calorimetry. Each of these lactose fractions were then blended separately with micronised salbutamol sulphate in a ratio of 67.5:1 (w/w). The mixing uniformity and percentage recovery of salbutamol sulphate in the powder blends were analysed using a validated HPLC method. The deposition profiles of the drug were determined using a 5-stage liquid impinger after aerosolisation at 60 l min(-1) via a Rotahaler. Despite the identical processing conditions, the lactose fractions were shown to differ in particle size, size distribution and concentrations of fine particles. The particles from each fraction also exhibited different surface textures and dissimilar DSC thermograms. However, all the blends of the lactose with salbutamol sulphate were found to have a relatively high uniformity of salbutamol sulphate content, as suggested by a coefficient of variation of less than 3.2%. Anhydrous and medium lactose produced a more efficient delivery of salbutamol sulphate when aerosolised from the Rotahaler in comparison to other grades of lactose. For example, the fine particle fraction (FPF) and fine particle dose (FPD) of drug from formulations containing anhydrous lactose were 13.4+/-4.2% and 57.3+/-17.6 microg, respectively, which were approximately two times higher than the respective values of the formulation containing regular lactose. Medium lactose resulted in drug FPF (7. 9+/-2.7%) and FPD (32.4+/-11.8 microg), which were significantly (ANOVA P<0.05) higher than the same parameters obtained using lactose crystals, foremost lactose and regular lactose. More efficient drug delivery from anhydrous lactose may be partly attributed to the relatively higher concentration of fine lactose in this grade of carrier, although it showed a rougher surface than the other grades of lactose. However, the relatively high FPF of the drug from medium lactose may have been due to the relatively small mean particle size and smooth surface of the particles. Therefore, the source and grade of lactose may have a substantial effect on drug delivery from dry powder inhaler formulations and care should be taken in establishing appropriate quality control parameters when selecting an appropriate grade of carrier.     

Novel alternative methods for the delivery of drugs for the treatment of asthma

Successful delivery of dry powder aerosols to the lung requires careful consideration of the powder production process, formulation and inhaler device. Newer production methods are emerging to prepare powders with desirable characteristics for inhalational administration. The conventional formulation approach of adding coarse lactose carriers to the drug to form binary powder systems to enhance powder flow and dispersion properties has been expanded to using finer carrier particles and hydrophobic materials, as well as ternary systems. Particle morphology and surface properties have also been explored to enhance powder performance. For the inhaler device, the new generation inhalers are designed to reduce or completely decouple the influence of air flow on the aerosol generation. Each of these determinants for powder aerosol delivery is reviewed with a strong focus on the patent literature that contains enormous information about the latest development in this field.     

Dry powder inhalations containing thymopentin and its immunomodulating effects in Wistar rats

Thymopentin (TP5), a synthetic pentapeptide, has been used in clinic as a modulator for immunodeficiences through intramuscular administration. The purpose of this study was to design and evaluate dry powder inhalations (DPIs) for pulmonary delivery of TP5. Dry powder inhalations containing leucine (a dispersibility enhancer), mannitol, and lactose (bulking agents) were prepared by spray-drying from aqueous formulations. The formulation components on the aerosolisation characteristics of spray-dried powders were investigated through the use of various amount of leucine, lactose and mannitol. Following spray-drying, resultant powders were characterized using scanning electron microscopy, laser diffraction and tapped density measurements, and the aerosolisation performance was determined using Twin Stage Impinger. The immunosuppression Wistar rats model was constructed to evaluate the immunomodulating effects of TP5 DPIs in vivo. The results of T-lymphocyte subsets (CD3+, CD4+, CD8+, CD4+/CD8+ ratio) analyses suggest that TP5 DPIs have modulating effects. On an overall evaluation, TP5 pulmonary delivery DPIs may be feasible for the future clinical application.     

A novel apparatus for rat in vivo evaluation of dry powder formulations for pulmonary administration

The lungs have attracted increasing attention as a site for administration of drugs, including macromolecules that are poorly absorbed from the intestine. There have been a number of basic studies in which peptide solutions were administered to experimental animals via the lungs. Although there have been several studies of pulmonary peptide absorption from dry powder formulations, a simpler and more inexpensive apparatus for administration of dry powders would enhance rapid screening of the formulations. In this study, we developed a simple apparatus to disperse dry powders. The apparatus has two 3-way stopcocks; one allows dispersal of powders at a constant pressure and airflow, and the other allows rats to breathe before and after administration. Dry powders of fluorescein (FL) and FITC-dextran (FD4) were manufactured by the spray-drying technique. The effects of operating conditions on the absorption of these model drugs were examined in rats. The C(max) for FL from dry powder was lower than that from solution and mean residence time was extended, suggesting that dissolution was the rate-determining step for FL absorption from dry powder. For FD4, the rate of absorption may not be regulated by dissolution but by epithelial transport. Absorption of insulin from spray-dried powder via the rat trachea was investigated using this apparatus. Intratracheally administered spray-dried insulin powder decreased plasma glucose level to a greater extent than spray-dried insulin solution administered via the same route. Thus, the apparatus is simple, inexpensive, and useful for rapid screening of dry powder formulations.     

Alternative sugars as potential carriers for dry powder inhalations

Most dry powder inhaler (DPI) formulations rely on lactose monohydrate as a carrier in the drug powder blends. However, lactose cannot be used for compounds that interact with the reducing sugar function of the lactose, such as formoterol, budesonide or peptides and proteins. In this study, alternative carriers like mannitol, glucose, sorbitol, maltitol and xylitol have therefore been evaluated for their potential use in DPI formulations. Raw materials were characterised physico-chemically and blends with the model drug substance budesonide were tested with respect to the aerosolization behaviour of the powders.

It was found out that similarly to the problems known for lactose monohydrate, such as supplier variability, variability between different qualities of one supplier, the same difficulties apply to the alternative carriers investigated. Different sources and qualities of mannitol led to significant differences in the fine particle fraction (FPF), varying from 15 to 50% for two different qualities of mannitol. Similar observations were made for the other carrier materials studied. Also, the influence of conditioning the raw material at different relative humidity was found to have substantial influence on the performance of drug/carrier blends which is characterised by a strong decrease in the FPF. In summary, mannitol showed potential as a drug carrier to be used in DPIs whereas the more hygroscopic sugars only showed poor dispersibility.     

Leucine as an excipient in spray dried powder for inhalation

Leucine is a promising excipient with several applications in the development of inhalable spray-dried powder of high- and low-dose drugs. The addition of leucine has exhibited significant enhancing effects on the aerosolization and physical stability of the produced particles. Here, we focus not only on the applications of leucine in inhalable spray-drying powders, but also on the underlying mechanisms by which the formulation and processing parameters dictate the behavior of leucine during the drying process and, therefore, its functionalities within the dried powder. Additionally, we highlight the current regulatory status of leucine. Such insights are important for more efficient utilization of leucine in the future, both for dry powder inhaler formulations and other pharmaceutical applications.     

Drug-lactose binding aspects in adhesive mixtures: controlling performance in dry powder inhaler formulations by altering lactose carrier surfaces

For dry powder inhaler formulations, micronized drug powders are commonly mixed with coarse lactose carriers to facilitate powder handling during the manufacturing and powder aerosol delivery during patient use. The performance of such dry powder inhaler formulations strongly depends on the balance of cohesive and adhesive forces experienced by the drug particles under stresses induced in the flow environment during aerosolization. Surface modification with appropriate additives has been proposed as a practical and efficient way to alter the inter-particulate forces, thus potentially controlling the formulation performance, and this strategy has been employed in a number of different ways with varying degrees of success. This paper reviews the main strategies and methodologies published on surface coating of lactose carriers, and considers their effectiveness and impact on the performance of dry powder inhaler formulations.     

A dry powder inhaler with reduced mouth-throat deposition.

A novel, compact, and highly efficient dry powder inhaler (DPI) with low mouth-throat deposition is described. The performance of this DPI was evaluated by measuring both (1) the total aerosol deposition in and distal to an idealized mouth-throat cast and (2) the fine particle fraction (FPF) using a standard Mark II Anderson impactor. Ultraviolet (UV) spectroscopy techniques were used in the aerosol deposition measurements. Two inhalation aerosol powders, namely budesonide (extracted from a Pulmicort/Turbuhaler multi-dose device, 200 microg/dose) and ciprofloxacin + lipid + lactose (in-house), were dispersed by the DPI at a steady inhalation flow rate of 60 L/min. The newly developed DPI had a total aerosol delivery distal to the mouth-throat cast of 50.5% +/- 3.04% and 69.7% +/- 1.5% for the budesonide and ciprofloxacin + lipid + lactose aerosols, respectively. This is a significant improvement over the Turbuhaler original device delivery of 34.5% +/- 5.2%, particularly considering that in vitro mouth-throat deposition dropped from 27.5% +/- 5.4% with the budesonide Turbuhaler to 11.0% +/- 3.5% with the present inhaler. The different lung deliveries from the same inhaler for the two formulations above also confirm that the overall performance of an inhaler is optimizable via powder formulations.