Formulation and process development of (recombinant human) deoxyribonuclease I as a powder for inhalation

A formulation and process development study was performed to formulate recombinant human deoxyribonuclease I as a powder for inhalation. First, excipient compatibility (with bovine DNase as a model substance) was examined with a stability study at stressed conditions (60 and 85°C) while monitoring for occurrence of the Maillard reaction. Next, powders for inhalation were prepared by spray drying and spray freeze drying. We found that spray drying with inulin as stabilizer resulted in the best powder for inhalation. Finally, an ex-vivo test with the spray dried rhDNase I/inulin powder significantly decreased elastic and viscous moduli of sputum from five cystic fibrosis patients.     

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.     

Microdialysis sampling and the clinical determination of topical dermal bioequivalence

The influence of the deposition pattern and spray characteristics of nasal powder formulations on the insulin bioavailability was investigated in rabbits. The formulations were prepared by freeze drying a dispersion containing a physical mixture of drum dried waxy maize starch (DDWM)/Carbopol^® 974P (90/10, w/w) or a spray-dried mixture of Amioca^® starch/Carbopol^® 974P (25/75, w/w). The deposition in the nasal cavity of rabbits and in a silicone human nose model after actuation of three nasal delivery devices (Monopowder, Pfeiffer and experimental system) was compared and related to the insulin bioavailability. Posterior deposition of the powder formulation in the nasal cavity lowered the insulin bioavailability.

To study the spray pattern, the shape and cross-section of the emitted powder cloud were analysed. It was concluded that the powder bulk density of the formulation influenced the spray pattern. Consequently, powders of different bulk density were prepared by changing the solid fraction of the freeze dried dispersion and by changing the freezing rate during freeze drying. After nasal delivery of these powder formulations no influence of the powder bulk density and of the spray pattern on the insulin bioavailability was observed.     

The impact of drying method and formulation on the physical properties and stability of methionyl human growth hormone in the amorphous solid state

The objective of this work was to investigate the impact of drying method and formulation on the physical stability (aggregation) and selected important physical properties of dried methionyl human growth hormone (Met-hGH) formulations. Solutions of Met-hGH with different stabilizers were dried by different methods (freeze drying, spray drying, and film drying), with and without surfactant. Properties of the dried powders included powder morphology, specific surface area (SSA), protein surface coverage, thermal analysis, and protein secondary structure. Storage stability of Met-hGH in different formulations was also studied at 50 degrees C and at 60 degrees C for 3 months. The dried powders displayed different morphologies, depending mainly on the method of drying and on the presence or absence of surfactant. Film dried powders had the lowest SSA (approximately 0.03 m(2)/g) and the lowest total protein surface accumulation (approximately 0.003%). Surfactant caused a reduction in the SSA of both spray dried and freeze dried powders. Spray dried powders showed greater protein surface coverage and SSA relative to the same formulations dried by other means. Greater in-process perturbations of protein secondary structure were observed with polymer excipients. Formulation impacted physical stability. In general, low molecular weight stabilizers provided better stability. For example, the aggregation rate at 50 degrees C of Met-hGH in a freeze dried trehalose-based formulation was approximately four times smaller than the corresponding Ficoll-70-based formulation. Drying method also influenced physical stability. In general, the film dried preparations studied showed superior stability to preparations dried by other methods, especially those formulations employing low molecular weight stabilizers.     

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.     

Physicochemical and in vitro deposition properties of salbutamol sulphate/ipratropium bromide and salbutamol sulphate/excipient spray dried mixtures for use in dry powder inhalers

The physicochemical and aerodynamic properties of spray dried powders of the drug/drug mixture salbutamol sulphate/ipratropium bromide were investigated. The in vitro deposition properties of spray dried salbutamol sulphate and the spray dried drug/excipient mixtures salbutamol sulphate/lactose and salbutamol sulphate/PEG were also determined. Spray drying ipratropium bromide monohydrate resulted in a crystalline material from both aqueous and ethanolic solution. The product spray dried from aqueous solution consisted mainly of ipratropium bromide anhydrous. There was evidence of the presence of another polymorphic form of ipratropium bromide. When spray dried from ethanolic solution the physicochemical characterisation suggested the presence of an ipratropium bromide solvate with some anhydrous ipratropium bromide. Co-spray drying salbutamol sulphate with ipratropium bromide resulted in amorphous composites, regardless of solvent used. Particles were spherical and of a size suitable for inhalation. Twin impinger studies showed an increase in the fine particle fraction (FPF) of spray dried salbutamol sulphate compared to micronised salbutamol sulphate. Co-spray dried salbutamol sulphate:ipratropium bromide 10:1 and 5:1 systems also showed an increase in FPF compared to micronised salbutamol sulphate. Most co-spray dried salbutamol sulphate/excipient systems investigated demonstrated FPFs greater than that of micronised drug alone. The exceptions to this were systems containing PEG 4000 20% or PEG 20,000 40% both of which had FPFs not significantly different from micronised salbutamol sulphate. These two systems were crystalline unlike most of the other spray dried composites examined which were amorphous in nature.     

Identification of Stability Constraints in the Particle Engineering of an Inhaled Monoclonal Antibody Dried Powder

Monoclonal antibody (mAb) based therapies may provide a valuable new treatment modality for acute and chronic lung diseases, including asthma, respiratory infections, and lung cancer. Currently mAbs are delivered via systemic administration routes, but direct delivery to the lungs via the inhaled route could provide higher concentrations at the site of disease and reduced off-target effects. Though lyophilized mAbs may be reconstituted and delivered to the lungs using nebulizers, dry powder inhalers provide a more patient-friendly delivery method based upon their fast administration time and portability. However, particle engineering processes required to prepare respirable dried powders for DPI delivery involve multiple potential stressors for mAbs, which have not been fully explored. In this study, a systematic examination of various aspects of the particle engineering process (atomization, freezing, drying, and storage) was performed to further understand their impact on mAb structure and aggregation. Using anti-streptavidin IgG1 as a model mAb, atomization settings were optimized using a design of experiments approach to elucidate the relationship between feed flow rate, formulation solid content, and atomization airflow rate and protein structural changes and aggregation. The optimized atomization conditions were then applied to spray drying and spray freezing drying particle engineering processes to determine the effects of freezing and drying on IgG1 stability and aerosol performance of the powders. IgG1 was found to be particularly susceptible to degradation induced by the expansive air-ice interface generated by spray freeze drying and this process also produced powders that exhibited decreased storage stability. This study further delineates the design space for manufacturing of respirable biologic therapies and is intended to serve as a roadmap for future development work.     

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.     

Optimization of Particle Properties of Nanocrystalline Solid Dispersion Based Dry Powder for Inhalation of Voriconazole

A one-step spray drying based process was employed to generate ready-to-use nanocrystalline solid dispersion (NCSD) dry powder for inhalation (DPI) of voriconazole (VRC). The solid dispersion was prepared by spray drying VRC, MAN (mannitol) and soya lecithin (LEC) from mixture of methanol-water. Various formulation and process related parameters were screened, including LEC, inlet temperature, total solid content and feed flow rate to generate particles of geometric size ≤5 µm. Aerosil® 200 was explored as the quaternary excipient either during spray drying or by physically mixing with the optimized ternary NCSD. The powders were extensively characterized for solid form, primary particle size, assay, embedded nanocrystal size, morphology, porosity, density and moisture content. Aerodynamic properties were studied using next generation impactor (NGI), while surface elemental composition and topography were investigated using SEM-EDS (scanning electron microscopy- energy dispersive spectroscopy) and AFM (atomic force microscopy), respectively. At selected inlet temperature of 120 ?C, total solid content and feed flow rate significantly impacted the size of primary NCSD particles. Size of primary particles increased with increase in total solid content and feed flow rate of the solution. VRC nanocrystals were obtained in polymorphic Form B whereas the matrix of MAN consisted of mixture of polymorphic Forms α, β and δ. SEM-EDS analysis confirmed deposition of Aerosil® 200 on surface of spray dried particles. In addition to increased porosity and reduced density, increase in surface roughness of particles (evident from AFM topographic analysis) contributed to enhanced powder deposition at stages 3 and 4 in NGI. In comparison, physical blending of NCSD with Aerosil® 200 showed improvement in aerosolization due to flow enhancement property.     

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.     

Spray Dried Powders and Powder Blends of Recombinant Human Deoxyribonuclease (rhDNase) for Aerosol Delivery

Purpose. We have used rhDNase to investigate the feasibility of developing a dry protein powder aerosol for inhalation delivery. Methods. Powders of rhDNase alone and with sodium chloride were prepared by spray drying. Powder blends were obtained by mixing (tumbling and sieving) pure rhDNase powder with 'carrier' materials (lactose, mannitol or sodium chloride). The weight percent of drug in the blends was between 5 and 70%. The particle size distributions and crystallinity of the spray dried powders were obtained by laser diffraction and X-ray powder diffraction, respectively. Particle morphology was examined by scanning electron microscopy. The ability of the powders and powder blends to be dispersed into respirable aerosols was measured using a Rotahaler connected to a multistage liquid impinger operating at 60 L/min. Results. Pure rhDNase powder was quite cohesive with a fine particle fraction (FPF or 'respirable fraction': % wt. of particles < 7 m in the aerosol cloud) of about 20%. When particles also contained NaCl, the powders were dispersed better to form aerosols. A linear relationship was observed between the NaCl content and FPF for a similar primary size (~3 m volume median diameter) of particles. The particle morphology of these powders varied systematically with the salt content. For the blends, SEM revealed a monolayer-like adhesion of the fine drug particles to the carriers at drug contents 50 % wt. An overall 2-fold increase in FPF of rhDNase in the aerosol cloud was obtained for all the blends compared to the pure drug aerosols. Conclusions. The aerosol properties of spray dried rhDNase powders can be controlled by incorporation of a suitable excipient, such as NaCl, and its relative proportion. Coarse carriers can also enhance the performance of rhDNase dry powder aerosols.     

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.     

Caffeine microparticles for nasal administration obtained by spray drying

This study investigated the possibility to use spray drying technique to prepare powders formulations containing caffeine intended for nasal delivery. Spray dried powders containing caffeine and excipients, as filler and shaper agents, were prepared. Powders were investigated for particle size, morphology and delivery properties from Monopowder P nasal insufflator, assessing the influence of each excipient on microparticles characteristics. The results showed that the excipients strongly affected microparticle properties. Size, shape and agglomeration tendency are relevant characteristics of spray dried nasal powder.     

Effects of drying methods on the physicochemical and compressional characteristics of Okra powder and the release properties of its metronidazole tablet formulation

A study has been made of the effects of sun and oven drying methods on the physicochemical characteristics and compressibility of Okra powder and the release properties of its metronidazole tablet formulation. Corn starch was used as the reference standard. The mechanical properties of the tablets were evaluated using crushing strength and friability, while the release properties were determined using the disintegration times and dissolution rates. The results obtained showed that sun-dried Okra powder had smaller particle size, exhibited good flow and possessed higher hydration and swelling capacities compared to the oven dried samples. The compressibility of Okra powders assessed by the indices of plasticity from Heckel (Py) and Kawakita plots (Pk) showed that sun dried Okra powders had higher Py but lower Pk values than the oven-dried Okra powder. Metronidazole tablets formulated with oven dried Okra powder formed stronger tablets than tablets containing sun dried Okra powder. Generally, tablets containing sun dried Okra powders had faster disintegration and dissolution than tablets formulated with oven-dried powder. The results suggest that the choice of drying method during the processing of pharmaceutical raw materials is critical to its physicochemical properties and the release properties of its tablet formulations.     

Constant size, variable density aerosol particles by ultrasonic spray freeze drying

This work provides a new understanding of critical process parameters involved in the production of inhalation aerosol particles by ultrasonic spray freeze drying to enable precise control over particle size and aerodynamic properties. A series of highly porous mannitol, lysozyme, and bovine serum albumin (BSA) particles were produced, varying only the solute concentration in the liquid feed, c(s), from 1 to 5 wt%. The particle sizes of mannitol, BSA, and lysozyme powders were independent of solute concentration, and depend only on the drop size produced by atomization. Both mannitol and lysozyme formulations showed a linear relationship between the computed Fine Particle Fraction (FPF) and the square root of c(s), which is proportional to the particle density, ρ, given a constant particle size d(g). The FPF decreased with increasing c(s) from 57.0% to 16.6% for mannitol and 44.5% to 17.2% for lysozyme. Due to cohesion, the BSA powder FPF measured by cascade impaction was less than 10% and independent of c(s). Ultrasonic spray freeze drying enables separate control over particle size, d(g), and aerodynamic size, d(a) which has allowed us to make the first experimental demonstration of the widely accepted rule d(a)=d(g)(ρ/ρ(o))(1/2) with particles of constant d(g), but variable density, ρ (ρ(o) is unit density).     

Drying-Induced Variations in Physico-Chemical Properties of Amorphous Pharmaceuticals and Their Impact on Stability II: Stability of a Vaccine

Objectives To investigate the impact of drying method on the storage stability of dried vaccine formulations. Materials and Methods A sucrose-based formulation of a live attenuated virus vaccine of a parainfluenza strain, with and without surfactant, was dried from by different methods; freeze drying, spray drying and foam drying. Dried powders were characterized by differential scanning calorimetry, specific surface area (SSA) analysis and by electron spectroscopy for chemical analysis (ESCA) to evaluate vaccine surface coverage in the dried formulations. Dried formulations were subjected to storage stability studies at 4, 25 and 37°C. The vaccine was assayed initially and at different time points to measure virus-cell infectivity, and the degradation rate constant of the vaccine in different dried preparations was determined. Results SSA was highest with the spray dried preparation without surfactant (∼ 2.8 m²/g) and lowest in the foam dried preparations (with or without surfactant) (∼ 0.1 m²/g). Vaccine surface coverage was estimated based on ESCA measurements of nitrogen content. It was predicted to be highest in the spray dried preparation without surfactant and lowest in the foam with surfactant. Stability studies conducted at 25°C and 37°C showed that the vaccine was most stable in the foam dried preparation with surfactant and least stable in spray dried preparations without surfactant and in all freeze dried preparations regardless of the presence of surfactant. Addition of surfactant did lower the SSA and vaccine surface coverage in freeze dried preparations but still did not improve storage stability. Conclusions In drying methods that did not involve a freezing step, good storage stability of Medi 534 vaccine in the dried form was found with low SSA and low vaccine surface accumulation, both of which integrate into low fraction of vaccine at the surface. Ice appears to be a major destabilizing influence.     

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。     

Influence of Particle Size,Air Flow,and Inhaler Device on the Dispersion of Mannitol Powders as Aerosols

Purpose. To study the effect of particle size, air flow and inhaler type on the dispersion of spray dried mannitol powders into aerosols. Methods. Mannitol powders were prepared by spray drying. The solid state properties of the powders were determined by laser diffraction, X-ray powder diffraction, scanning electron microscopy, freeze fracture, Karl Fischer titration and gas pycnometry. The powders were dispersed using Rotahaler^® and Dinkihaler^®, connected to a multistage liquid impinger at different air flows. Results. Three crystalline mannitol powders with primary particle size (MMD) 2.7, 5.0, 7.3 m and a similar polydispersity were obtained. The particles were spherical with a density of 1.5 g/cm³ and a moisture content of 0.4 wt.%. At an air flow of 30 L/min all the powders were poorly dispersed by both inhalers. With the Rotahaler^® increasing the flow (60–120 L/min) increased the fine particle fraction (FPF) in the aerosols for the 2.7 m powder, and decreased the FPF for the 7.3 m powder; whereas the FPF for 5.0 m powder was unaffected. With the Dinkihaler^®, all the powders were near complete dispersion at 60 L/min. Conclusions. The FPF in the mannitol powder aerosols was determined by an interplay of the particle size, air flow and inhaler design.     

Production of salbutamol sulfate for inhalation by high-gravity controlled antisolvent precipitation

The purpose of this study was to produce salbutamol sulfate (SS) as a model anti-asthmatic drug using high-gravity controlled precipitation (HGCP) through antisolvent crystallisation. An aqueous solution of SS was passed through a HGCP reactor with isopropanol as antisolvent to induce precipitation. Spray drying was employed to obtain dry powders. Scanning electron microscopy, X-ray powder diffraction (XRD), density measurement, thermal gravimetric analysis, and dynamic vapour sorption were carried out to characterise the powder physical properties. The aerosol performance of the powders was measured using an Aeroliser connected to a multiple stage liquid impinger operating at 60 L/min. The HGCP SS particles were elongated with 0.1 microm in width but varying length of several mum, which formed spherical agglomerates when spray dried. The particles showed the same XRD pattern and true density (1.3g/cm3) as the raw material, indicating that they belonged to the same crystalline form. However, the spray dried agglomerates had a much lower tapped density (0.1g/cm3) than the raw material (0.6g/cm3). Compared with the powder obtained by spray drying directly from an aqueous solution, the SS powders obtained from HGCP were much less hygroscopic (0.6% versus 10% water uptake at 90% RH). The in vitro aerosol performance showed a fine particle fraction FPFloaded and FPFemitted up to 54.5+/-4.9% and 71.3+/-10.0%, respectively. In conclusion, SS powder with suitable physical and aerosol properties can be obtained through antisolvent HGCP followed by spray drying.