Spray freeze drying to produce a stable Delta(9)-tetrahydrocannabinol containing inulin-based solid dispersion powder suitable for inhalation.

The purpose of this study is to investigate whether spray freeze drying produces an inhalable solid dispersion powder in which Delta(9)-tetrahydrocannabinol (THC) is stabilised. Solutions of THC and inulin in a mixture of tertiary butanol (TBA) and water were spray freeze dried. Drug loads varied from 4 to 30 wt.%. Various powder characteristics of the materials were determined. Stability of THC was determined and compared with freeze dried material. The powders, dispersed with an inhaler based on air classifier technology, were subjected to laser diffraction analysis and cascade impactor analysis. Highly porous particles having large specific surface areas (about 90 m(2)/g) were produced. At high drug loads, THC was more effectively stabilised by spray freeze drying than by freeze drying. Higher cooling rates during spray freeze drying result in improved incorporation. Fine particle fractions of up to 50% were generated indicating suitability for inhalation. It was concluded that spray freeze drying from a water-TBA mixture is a suitable process to include lipophilic drugs (THC) in inulin glass matrices. High cooling rates during the freezing process result in effective stabilisation of THC. The powders can be dispersed into aerosols with a particle size appropriate for inhalation.     

Cospray dried antibiotics for dry powder lung delivery

The aim of this study was to assess the potential of delivering a combination antibiotic therapy, containing doxycycline and ciprofloxacin (both hydrochloride) as a dry powder (DPI) formulation for inhalation. Single and combination antibiotics were produced by spray drying. Particle size distributions were characterized by laser diffraction and imaging conducted by scanning electron microscopy. Solid-state characterisation of the antibiotics was carried out using differential scanning calorimetry, dynamic vapour sorption, X-ray powder diffraction, and differential scanning calorimetry. Using the Aerolizer device, the aerosol performance was measured using multistage liquid impinger and analysed using high performance liquid chromatography (R(2) = 1.0, CV = 0.4-1.0%). Furthermore, a disk diffusion test was performed for the assessment of the in vitro antimicrobial activity of the raw and spray dried antibiotics against bacteria. Results showed that cospray drying of the ciprofloxacin and doxycycline produced an antibiotic formulation (in a 1:1 ratio) suitable for inhalation that showed to be physically more stable then the analogous single spray dried antibiotic. The cospray dried powder has improved dispersion over the less stable single spray dried ciprofloxacin. The spray dried antibiotics were observed to have similar antimicrobial activity to the original antibiotics for Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyrogenes, suggesting the spray drying process does not affect the anti-bacterial activity of the drug. Cospray dried antibiotics from a DPI is thus feasible and can potentially be an attractive delivery alternative to the more conventional systemic delivery route.     

The role of particle engineering in relation to formulation and de-agglomeration principle in the development of a dry powder formulation for inhalation of cetrorelix.

We formulated cetrorelix acetate, as an adhesive mixture for use in dry powder inhalation. To achieve the highest possible deposition efficiency we investigated both the influence of different micronization techniques and different inhalers. The Novolizer with an air classifier as the powder de-agglomeration principle and the ISF inhaler were used for in vitro deposition experiments (cascade impaction). Micronization by milling as the classical approach and micronization by spray drying and spray freeze drying as advanced particle engineering techniques were investigated to determine whether advanced techniques are necessary to obtain high fine particle fractions (FPF) for this specific drug. It was found that the effects obtained with a certain micronization technique depended on the complex interaction of the physical characteristics of the drug substance with the type of formulation chosen, as well as with the de-agglomeration principle used. The combination of particle engineering by spray drying and the use of the air classifier technology resulted in a fine particle fraction of 66%, while spray freeze drying yielded extremely fragile particles resulting in a FPF of only 25%. The behaviour of the milled material showed similar trends as the spray dried material but FPF values were lower. It was concluded that when a drug is to be formulated as a powder for inhalation with high fine particle fractions, it is profitable to use advanced particle engineering techniques, however the applied technique should be tuned with the characteristics of the formulation type and process as well as with device development.     

吸入粉雾剂的喷雾工艺及表征研究进展

吸入粉雾剂是改善肺部疾病治疗的研究热点,具有上市产品多、生产工艺成熟、颗粒影响因素多、晶型转化因素多、颗粒表面物性变化等特点。目前,吸入粉雾剂存在产品效用、贮藏及生产工艺因素的关联研究不系统等问题,本文对近年来肺部吸入粉雾剂制备新技术（喷雾冷冻干燥技术、微流控-喷雾技术、模板打印技术）及粉体颗粒物理化学表征新技术（反向气相色谱、原子力显微镜测定技术、能量色散X射线光谱技术、飞行时间-离子质谱法等）进行综述,以期对该剂型的研发提供新的借鉴。     

Local and systemic delivery of high-molecular weight drugs by powder inhalation

The pulmonary route has recently attracted attention as a noninvasive administration route for peptide and protein drugs, and an insulin powder for inhalation was approved by authorities in Europe and the USA. The present study examined usefulness of insulin and gene powders for systemic and local inhalation therapy. We prepared several dry insulin powders by spray drying to examine the effect of additives on insulin absorption. Citric acid appears to be a safe and potent absorption enhancer for insulin in dry powder. However, in the powder with citric acid (MIC0.2 SD) insulin was unstable compared with the other powders examined. To improve insulin stability, a combination of insulin powder and citric acid powder was prepared (MIC Mix). MIC Mix showed hypoglycemic activity comparable to MIC0.2 SD while the insulin stability was much better than that of MIC SD. Next, dry insulin powders with mannitol were prepared with supercritical carbon dioxide (SCF); the powder thus prepared reduced blood glucose level rapidly and was more effective than that prepared by spray drying. Chitosan-pDNA complex powders as a pulmonary gene delivery system were also prepared with SCF and their in vivo activity was evaluated. The addition of chitosan suppressed the degradation of pCMV-Luc during preparation and increased the storage stability. The luciferase activity in mouse lung was evaluated after pulmonary administration of the powders. The chitosan-pDNA powder with an N/P ratio=5 increased the luciferase activity to 27 times that of the pCMV-Luc solution. These results suggest that gene powder with chitosan is a useful pulmonary gene delivery system.     

含碳酸氢铵羟基喜树碱粉雾剂的研制

目的:提高10-羟基喜树碱(HPCT)粉雾剂的沉积性能。方法:利用喷雾干燥法制备HPCT粉雾剂,考察处方中加入碳酸氢铵后粉末的密度、比表面积、表面形态、粒度及体外沉积性能。结果:制备出了敲击密度为0.015g·mL-1、比表面积为19.81m2·g-1、体积平均直径为15.64μm的粉末,该低密度、大粒径的多孔性粉粒大大提高了药物的体外沉积性能,粉雾剂的体外沉积率由18.0%提高至51.6%。结论:加入碳酸氢铵能够显著提高HPCT粉雾剂的沉积性能。     

Studies on the spray dried lactose as carrier for dry powder inhalation

The purpose of this study was to investigate the spray dried lactose as carrier for dry powder inhalation (DPI). The lactose particles were prepared by spray drying, then the particle size, shape and crystal form were characterized by laser diffraction, scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The spray dried lactose particles were spherical and amorphous, but would transfer to crystal form when storage humidity was above 32%. Thus, the humidity of the storage environment should be controlled below 30% strictly in order to maintain the amorphous nature of spray dried lactose which is a great benefit to DPI development.     

Characterization of a cyclosporine solid dispersion for inhalation

For lung transplant patients, a respirable, inulin-based solid dispersion containing cyclosporine A (CsA) has been developed. The solid dispersions were prepared by spray freeze-drying. The solid dispersion was characterized by water vapor uptake, specific surface area analysis, and particle size analysis. Furthermore, the mode of inclusion of CsA in the dispersion was investigated with Fourier transform infrared spectroscopy. Finally, the dissolution behavior was determined and the aerosol that was formed by the powder was characterized. The powder had large specific surface areas (~ 160 m(2)). The water vapor uptake was dependant linearly on the drug load. The type of solid dispersion was a combination of a solid solution and solid suspension. At a 10% drug load, 55% of the CsA in the powder was in the form of a solid solution and 45% as solid suspension. At 50% drug load, the powder contained 90% of CsA as solid suspension. The powder showed excellent dispersion characteristics as shown by the high emitted fraction (95%), respirable fraction (75%), and fine-particle fraction (50%). The solid dispersions consisted of relatively large (x(50) approximately 7 mum), but low-density particles (rho approximately 0.2 g/cm(3)). The solid dispersions dissolved faster than the physical mixture, and inulin dissolved faster than CsA. The spray freeze-drying with inulin increased the specific surface area and wettability of CsA. In conclusion, the developed powder seems suitable for inhalation in the local treatment of lung transplant patients.     

Design and evaluation of inhalable chitosan-modified poly (DL-lactic-co-glycolic acid) nanocomposite particles

The aim of this study was to investigate two types of chitosan-modified poly (DL-lactic-co-glycolic acid) (PLGA) nanocomposite particles containing salmon calcitonin for pulmonary delivery, which were obtained using spray drying fluidized bed granulation (Agglomaster?) and dry powder coating techniques (Mechanofusion?), respectively. The physicochemical properties, pulmonary distribution, pulmonary clearance rate as well as in vivo hypocalcemia actions of the two types of nanocomposite particles were investigated. As indicated by scanning electron micrographs, soft matrix nanocomposite particles and soft ordered nanocomposite particles were produced by Agglomaster? and Mechanofusion?, respectively. Both forms of chitosan-modified PLGA nanocomposite particles exhibited a high inhalation efficiency, i.e. more than 50% of the two types of nanocomposite particles could be deposited in the deep lung of male Wistar rats. However, the chitosan-modified PLGA nanocomposite particles designed by Agglomaster? exhibited superior properties to those obtained by Mechanofusion? with respect to the redispersibility of fine particles in aqueous liquid, the pulmonary retention time and pharmacological effects. In addition, compared with non-modified PLGA nanocomposite particles, the chitosan-modified PLGA nanocomposite particles obtained by Agglomaster? exhibited enhanced pulmonary absorption of salmon calcitonin via the lung. The findings in this study suggest that the spray drying fluidized bed granulation technique is superior to the dry powder coating technique for producing chitosan-modified dry powder formulations containing salmon calcitonin for inhalation. This can be attributed to the avoidance of aggregation of chitosan-modified PLGA nanocomposite particles when using Agglomaster? rather than Mechanofusion?.     

Formulation of pH responsive peptides as inhalable dry powders for pulmonary delivery of nucleic acids

Nucleic acids have the potential to be used as therapies or vaccines for many different types of disease, but delivery remains the most significant challenge to their clinical adoption. pH responsive peptides containing either histidine or derivatives of 2,3-diaminopropionic acid (Dap) can mediate effective DNA transfection in lung epithelial cells with the latter remaining effective even in the presence of lung surfactant containing bronchoalveolar lavage fluid (BALF), making this class of peptides attractive candidates for delivering nucleic acids to lung tissues. To further assess the suitability of pH responsive peptides for pulmonary delivery by inhalation, dry powder formulations of pH responsive peptides and plasmid DNA, with mannitol as carrier, were produced by either spray drying (SD) or spray freeze drying (SFD). The properties of the two types of powders were characterised and compared using scanning electron microscopy (SEM), next generation impactor (NGI), gel retardation and in vitro transfection via a twin stage impinger (TSI) following aerosolisation by a dry powder inhaler (Osmohaler™). Although the aerodynamic performance and transfection efficacy of both powders were good, the overall performance revealed SD powders to have a number of advantages over SFD powders and are the more effective formulation with potential for efficient nucleic acid delivery through inhalation.     

Production of Ultrafine Sumatriptan Succinate Particles for Pulmonary Delivery

PURPOSE: Drug particle physical properties are critical for the efficiency of a drug delivered to the lung. The purpose of this study was to produce ultrafine sumatriptan succinate particles for inhalation. METHODS: Sumatriptan succinate particles were produced via reactive precipitation without any surfactants. Several low toxic organic solvents such as acetone, isopropanol, and tetrahydrofuran were investigated as the reaction medium. And the dry powder was obtained via spray drying. FT-IR, HPLC, SEM and XRD were exploited to characterize the physicochemical properties of the ultrafine sumatriptan succinate dry powder. The aerosol performance of the powder was evaluated using an Aeroliser connected to a multi stage liquid impinger operating at 60 l/min. RESULTS: The mean particle size of the ultrafine sumatriptan succinate particles obtained under optimum conditions was in the range of 630-679 nm and consequently they were in the respirable range. The spray-dried powder whose fine particle fraction was increased up to 50.6 +/- 8.2% showed good aerosol performance whereas the vacuum-dried powder was approximate 18.2 +/- 3.0%. CONCLUSIONS: Good aerosol performance ultrafine sumatriptan succinate particles could be produced by reactive precipitation without any additives followed by spray drying at the optimum parameters.     

Improvement of insulin absorption from intratracheally administrated dry powder prepared by supercritical carbon dioxide process

The purpose of this study was to improve insulin absorption from dry powder after administration in lung without an absorption enhancer. The dry powders, with mannitol as a carrier, were prepared with or without an absorption enhancer (citric acid) by supercritical carbon dioxide (SCF) and spray drying (SD) processes. Insulin powder was precipitated from dimethyl sulfoxide and aqueous solutions by dispersing the insulin solutions from parallel and V-type nozzles, respectively, into supercritical carbon dioxide, which is an antisolvent for insulin. In vitro aerosol performance was evaluated with a cascade impactor. Insulin powder containing citric acid prepared by the SCF method (MIC SCF) showed improved inhalation performance compared with insulin powder prepared by the SD process, although the particle size of the former powder was larger than that in powders prepared by SD. Insulin absorption was estimated from the change in plasma glucose level. The blood glucose level after administration of the insulin powder without citric acid prepared by the SCF process (MI SCF) decreased rapidly, and a significant difference was observed for areas under the curve of change in plasma glucose concentration versus time (AUCs) between MI SCF and the insulin powder without citric acid prepared by the SD process (MI SD). These results suggest that the SCF technique would be useful to prepare dry powders suitable for inhalation.     

Spray drying of fenofibrate loaded nanostructured lipid carriers

The conversion of aqueous dispersion of nanostructured lipid carriers (NLCs) into dry powder by spray drying could be a useful approach to render NLCs with better physical chemical stability than the aqueous dispersion. In this study, aqueous NLC dispersion containing fenofibrate was converted into dry, easily reconstitutable powder using spray drying. A central composite face centered design (CCFD) was used to investigate the influence of the ratio of lipid to protectant (mannitol and trehalose) and crystallinity of spray-dried powder on the particle size, yield and residual moisture content of the dried powder. A linear relationship (R² = 0.9915) was established between the crystalline content of the spray-dried powders against the ratio of mannitol to trehalose from 3:7 to 10:0 (w/w). Spray drying of NLC aqueous dispersion using a mannitol and trehalose mixture resulted in an increase in particle size of the NLCs after reconstitution in water as compared to that in the initial aqueous dispersion. The decrease in crystallinity of the dry powder by reducing the ratio of mannitol to trehalose could improve the reconstitution of the NLCs in water. However the yield and residual moisture content of dry powder decreased with an increase in the ratio of mannitol to trehalose. Lipid nanoparticles were able to retain the drug incorporation and the prolonged drug release profile after spray drying. The experimental model was robust, and suggested that spray drying is a viable technique for the conversion of NLCs into dry powder.     

Particle engineering of materials for oral inhalation by dry powder inhalers. II-Sodium cromoglicate

Sodium cromoglicate is an antiasthmatic and antiallergenic drug used in inhalation therapy and commonly administered by a dry powder inhaler. In the present study we sought to examine the feasibility of producing nanoporous microparticles (NPMPs) of this hydrophilic material by adaptation of a spray drying process previously applied to hydrophobic drugs, and to examine the physicochemical and in vitro deposition properties of the spray dried particles in comparison to a commercial product. The storage stability of successfully prepared NPMPs was assessed under a number of conditions (4°C with dessicant, 25°C at 60% relative humidity and 25°C with dessicant). Spray dried sodium cromoglicate was amorphous in nature. NPMPs of sodium cromoglicate displayed superior aerodynamic properties resulting in improved in vitro drug deposition, as assessed by Andersen Cascade Impactor and twin impinger studies, in comparison to the commercial product, Intal. Deposition studies indicated that porosity and sphericity were important factors in improving deposition properties. The optimum solvent system for NPMP production was water:methanol:n-butyl acetate, as spherical NPMPs spray dried from this solvent system had a higher respirable fraction than non-spherical NPMPs of sodium cromoglicate (spray dried from methanol:n-butyl acetate), non-porous sodium cromoglicate (spray dried from water) and micronised sodium cromoglicate (Intal). While particle morphology was altered by storage at high humidity (60% RH) and in vitro deposition performance deteriorated, it was possible to maintain NPMP morphology and aerosolisation performance by storing the powder with dessicant.     

Preparation of inhalable salbutamol sulphate using reactive high gravity controlled precipitation

Reactive high gravity controlled precipitation (HGCP) was carried out to produce salbutamol sulphate (SS) particles suitable for inhalation. Aqueous solutions of free salbutamol base and sulphuric acid were mixed intensely inside a HGCP reactor to form the particles. Spray drying was employed to obtain dry powders. Physical properties of the powders were characterised by scanning electron microscopy, X-ray powder diffraction, thermal gravimetric analysis and dynamic water vapour sorption. Aerosol performance of the powders was measured using an Aeroliser connected to a multiple stage liquid impinger operating at 60 L/min. The results showed that the reactive HGCP powder, comprising primary SS sub-micron particles (approximately 100 nm in width and approximately 500 nm in length) packed into loose spherical agglomerates of about 2 microm in diameter, is of the same polymorphic form as the raw crystalline material, has a high specific surface area (24.7 +/- 0.1 m(2)/g), but a low moisture content (0.2%) and low moisture uptake (1.4% at RH 90%). The aerosol performance of the reactive HGCP powder is excellent, showing FPF(loaded) and FPF(emitted) of 76 +/- 5% and 83 +/- 7%, respectively, with low capsule and device retention. In conclusion, reactive HGCP followed by spray drying is suitable to produce stable crystalline powders of salbutamol with enhanced inhalation properties.     

喷雾与减压干燥的秦香止泻干膏粉吸湿性及流动性比较

目的比较喷雾干燥法与减压干燥法对秦香止泻干浸膏粉吸湿性及流动性的影响,为确定秦香止泻浓缩液（或稠浸膏）合理的干燥方法提供依据。方法通过测定秦香止泻干浸膏粉的吸湿速度,吸湿量达2％时的相对湿度（relative humidit,RH）,建立其动力学模型,提取吸湿速度参数并比较大小;通过测定秦香止泻干浸膏粉的休止角比较流动性优劣。结果两种干燥方法制成的干浸膏粉吸湿动力学模型皆符合对数正态分布模型,减压干燥比啧雾干燥吸湿速度快,吸湿量随RH变化的函数关系,喷雾干燥粉符合逻辑斯蒂模型;减压干燥粉符合修正指数函数曲线,吸湿量达2％时的RH,喷雾干燥粉为90．12％;减压干燥85．81％,减压干燥法比喷雾干燥法制成的干浸膏粉休止角大,流动性差。结论喷雾干燥制成的干浸膏粉不易吸湿,稳定性好,流动性好。     

Particle Engineering for Pulmonary Drug Delivery

With the rapidly growing popularity and sophistication of inhalation therapy, there is an increasing demand for tailor-made inhalable drug particles capable of affording the most efficient delivery to the lungs and the most optimal therapeutic outcomes. To cope with this formulation demand, a wide variety of novel particle technologies have emerged over the past decade. The present review is intended to provide a critical account of the current goals and technologies of particle engineering for the development of pulmonary drug delivery systems. These technologies cover traditional micronization and powder blending, controlled solvent crystallization, spray drying, spray freeze drying, particle formation from liquid dispersion systems, supercritical fluid processing and particle coating. The merits and limitations of these technologies are discussed with reference to their applications to specific drug and/or excipient materials. The regulatory requirements applicable to particulate inhalation products are also reviewed briefly.     

Recent advances in liposomal dry powder formulations: preparation and evaluation

Liposomal drug dry powder formulations have shown many promising features for pulmonary drug administration, such as selective localization of drug within the lung, controlled drug release, reduced local and systemic toxicities, propellant-free nature, patient compliance, high dose carrying capacity, stability and patent protection. Critical review of the recent developments will provide a balanced view on benefits of liposomal encapsulation while developing dry powder formulations and will help researchers to update themselves and focus their research in more relevant areas. In liposomal dry powder formulations (LDPF), drug encapsulated liposomes are homogenized, dispersed into the carrier and converted into dry powder form by using freeze drying, spray drying and spray freeze drying. Alternatively, LDPF can also be formulated by supercritical fluid technologies. On inhalation with a suitable inhalation device, drug encapsulated liposomes get rehydrated in the lung and release the drug over a period of time. The prepared LDPF are evaluated in vitro and in vivo for lung deposition behavior and drug disposition in the lung using a suitable inhaler device. The most commonly used liposomes are composed of lung surfactants and synthetic lipids. Delivery of anticancer agents for lung cancer, corticosteroids for asthma, immunosuppressants for avoiding lung transplantation rejection, antifungal drugs for lung fungal infections, antibiotics for local pulmonary infections and cystic fibrosis and opioid analgesics for pain management using liposome technology are a few examples. Many liposomal formulations have reached the stage of clinical trials for the treatment of pulmonary distress, cystic fibrosis, lung fungal infection and lung cancer. These formulations have given very promising results in both in vitro and in vivo studies. However, modifications to new therapies for respiratory diseases and systemic delivery will provide new challenges in conducting well-designed inhalation toxicology studies to support these products, especially for chronic diseases.     

柴藿颗粒浸膏喷雾干燥工艺研究

目的:优选柴藿颗粒浸膏喷雾干燥的最佳工艺条件.方法:采用L9(34)正交实验法对影响浸膏喷雾干燥的工艺条件:浸膏密度(A)、喷雾速度(B)、出口温度(C)进行考察,每个因素三个水平,并以柴藿颗粒浸膏喷雾干燥的出粉率为考察指标.结果:柴藿颗粒浸膏喷雾干燥最佳工艺条件为A1B3C2,即浸膏密度0.8 g/mL、喷雾速度2 mL/min、出口温度80℃.结论:该工艺稳定、有效、可控,为中试生产工艺提供了科学的理论依据.