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Spray-dried products, such as synthetic peptides and hormones, have already been approved by the U.S. Food and Drug Agency and the European Medicines Agency, while spray-dried antibodies or interleukins, are not yet available on the market. Concerning the latter group, knowledge on whether and how spray-drying (SD) can be performed without adversely affecting their biological activity is lacking. Accordingly, this study aimed at establishing a SD process (Buchi B-90 spray dryer) using three Interleukin-8 based proteins (7–74 kDa) that were dispersed in phosphate buffered saline to maintain their stability. A Box-Behnken Design of Experiments was conducted to identify the appropriate process parameters taking into account the thermal stability of interleukin-8. In parallel, a FD process was developed. Both powders were stored for up to 12 weeks. Powder characterization included residual moisture evaluation and the mean particle size of the SD powder was investigated with Laser Diffraction Analysis. The hydrodynamic volume was measured via size exclusion chromatography and sodium dodecyl sulfate–polyacrylamide gel electrophoresis. The secondary structure of the model proteins in the solid state was assessed with Fourier-transformation infrared spectroscopy for detecting the protein folding patterns and reconstituted with Circular Dichroism Spectroscopy. Finally, the binding affinity was studied with Surface Plasmon Resonance and Isothermal Fluorescence Titration, the protein stability with Chaotropic Unfolding, and the activity studies were carried out with the chemotaxis assay. The results showed that SD and FD powders with a residual moisture of less than 5 wt% were obtained. The interleukins showed no unfolding upon processing, neither in solid state nor reconstituted. Oligomerization was observed for FD, but not for SD interleukins. However, the unfolding, binding affinity and activity of all interleukins examined did not decrease in neither SD nor FD powders, even after 12 weeks of storage. Thus, it can be concluded that SD of interleukin formulations at outlet temperatures close to ambient temperature is a promising process for transferring them into a stable powder.

Spray drying is a technique that can be used to stabilize biopharmaceuticals, such as vaccines, within dry particles. Compared to liquid pharmaceutical products, dry powder has the potential to reduce costs associated with refrigerated storage and transportation. In this study, spray drying was investigated for processing an adjuvanted tuberculosis subunit vaccine, formulated as an oil-in-water nanoemulsion, into a dry powder composed of microparticles. Applying in-silico approaches to the development of formulation and processing conditions, successful encapsulation of the adjuvanted vaccine within amorphous microparticles was achieved in only one iteration, with high retention (>90%) of both the antigen and adjuvant system. Moisture-controlled stability studies on the powder were conducted over 26 months at temperatures up to 40 °C. Results showed that the powder was physically stable after 26 months of storage for all tested temperatures. Adjuvant system integrity was maintained at temperatures up to 25 °C after 26 months and after one month of storage at 40 °C. The spray-dried product demonstrated improved antigen thermostability when stored above refrigerated temperatures as compared to the liquid product. These results demonstrate the feasibility of spray drying as a method of encapsulating and stabilizing an adjuvanted vaccine.

To increase their stability, therapeutic (or monoclonal) antibodies (mAbs) are often formulated as solids by using a variety of drying techniques, e.g. freeze-drying, spray-drying, or spray freeze-drying. The addition of excipients is required to preserve stability of the protein during the drying process and subsequent storage of the resulting solid form. The addition of low molecular weight excipients, such as amino acids, to sugar based spray- and freeze-dried formulations has been suggested to improve the storage stability of proteins in the dried state. In this study sugars (sucrose, trehalose), amino acids (Gly, Ala, Pro, Ser, Val, Leu, Ile, Gln, His, Lys, Arg, Phe, Trp) and combinations thereof were investigated for their stabilizing effect during spray-drying and subsequent storage and for their reconstitution time reducing effect. Two IgG4 mAbs were used as model antibodies. From an initial screening study, basic and small neutral amino acids, in combination with a sugar, such as sucrose or trehalose, showed reconstitution time reducing and stabilizing properties. Arg in particular displayed excellent reconstitution and stability enhancing properties. Moreover, Arg was the only amino acid providing stabilizing properties comparable to sucrose or trehalose. Previous work by the authors described a statistically substantiated comparison between the three basic amino acids in a sugar containing formulation, albeit limited to a single concentration level [5]. Therefore, a follow-up design of experiments (DoE) study was performed to determine the optimum trehalose/amino acid content required for an optimal protein stability and reconstitution time and to compare the effects of two basic amino acids, Lys and Arg, to those of two neutral amino acids, Gly and Pro. The conducted DoE covered a wide range of trehalose (30-120 mM) and amino acid (50-150 mM) concentrations. The concentration of trehalose was found to be the main contributor to a reduction in reconstitution time and an increase in stability. Here we show that the addition of amino acids such as Gly, Pro, and Lys does not improve stability nor does it reduce the reconstitution time. Of the tested amino acids, only Arg showed a marked reduction in reconstitution time and improvement in stability compared to a trehalose. Moreover, the properties displayed by Arg could justify its application as the main stabilizer in spray-dried mAb formulations, eliminating the need for a sugar matrix altogether. But the weight ratio of stabilizer to protein was found the factor exerting the strongest overall influence on the formulation's reconstitution time and stability. More specifically, sufficient physical stability and an acceptable reconstitution time could be obtained with a protein to stabilizer weight ratio of at least 1:1. ispartof: EUROPEAN JOURNAL OF PHARMACEUTICS AND BIOPHARMACEUTICS vol:156 pages:131-142 ispartof: location:Netherlands status: published

Tuberculosis is still one of the leading causes of death from a single infectious agent (i.e. Mycobacterium tuberculosis). First line therapy includes per oral administration of high doses of rifampicin over several months and is often times accompanied by the occurrence of unwanted side effects that might limit the patient’s adherence to the therapy. Thus, local antibiotic treatment at the site of infection i.e. the lungs is desirable. Amongst other approaches, spray drying of solutions of rifampicin has been shown as suitable method to produce respirable dry powders. In this work, we present inhalable formulations manufactured via spray drying of aqueous solutions of rifampicin. Powders manufactured were characterized for their aerodynamic and solid state properties, as well as their physical and chemical stability. The main focus of this study was to investigate the mechanism of particle formation using an acoustic levitator. Fine particle fractions of the test formulations ranged from 80 to 89% whereas a reference formulation (a spray dried isopropyl alcoholic solution of rifampicin) showed a lower fine particle fraction of 37%. Acoustic levitator and surface tension experiments showed that interfacial properties of rifampicin lead to early crust formation upon drying of the droplets, which eventually decoupled from the liquid core and formed highly collapsed, low apparent density powders with excellent aerosol properties.

Active pharmaceutical ingredient (API) nanosuspensions from naproxen (Nap) and itraconazole (Itra) stabilized with Kollidon®VA64 (KVA) and sodium dodecyl sulfate (SDS) were produced in two different size classes each by wet media milling. These API nanosuspensions were spray dried with lactose, trehalose and sucrose as matrix formers in different proportions and at different drying temperatures (Toutlet). Toutlet as well as the API content significantly influenced the redispersibility of the API nanoparticles. It could be shown that these two parameters are related to each other, with an increasing API content leading to a decreasing maximum applicable Toutlet (Tcritical). Drying above Tcritical always led to an alteration of the size characteristics of the API nanoparticles and thus to a non-redispersible product with respect to the defined quality criteria. For each proportion of API to matrix former, a Tcritical could be found. Tcritical showed a linear relation to the API content. The linear regression of this relation was defined as process boundary. The y-intercept of the process boundary correlated well with the glass transition temperature (Tg) of the pure matrix former used for spray drying. The two APIs under investigation led to virtually identical behaviour if other parameters were kept constant. The particle size of the initial nanosuspension had an important influence. Nanosuspensions with comparatively small particle sizes led to a significantly stronger decrease of the process boundaries compared to the use of larger particle sizes. The maximum API content that leads to a redispersible product is thus decisively determined by Toulet of the spray dryer, Tg as well as the proportion of the matrix former and by the particle size of the API nanoparticles used.

While nanoparticulate drugs for deep lung delivery hold promise for particular disease treatments, their size-related physical instability and tendency of being exhaled during breathing remain major challenges to their inhaled formulation development. Here we report a viable method for converting drug nanosuspensions into inhalable, stable and redispersible nano-agglomerates through combined in-situ thermal gelation and spray drying. Itraconazole (ITZ) nanosuspensions were prepared by flash nanoprecipitation, and co-spray dried with two different grades of the gel-forming polymer, methylcellulose (MC M20 and MC M450) as protectants. MC M20 was found superior in protecting ITZ nanoparticles against thermal stress (through nanoparticle entrapment within its gel network structure) during spray drying. In terms of redispersibility, an Sf/Si ratio (i.e., ratio of nanoparticle sizes after and before spray drying) of unity (1.02 ± 0.03), reflecting full particle size preservation, was achieved by optimizing the suspending medium content and spray drying parameters. Formulation components, nanosuspension concentration and spray drying parameters all showed a significant impact on the aerosol performance of the resulting agglomerates, but an absence of defined trends or correlations. Overall, the MC-protected nano-agglomerates displayed excellent in-vitro aerosol performance with fine particle fractions higher than 50% and mass median aerodynamic diameters within the 2-3 µm range, which are ideal for deep lung delivery.

In anticipation of non-invasive routes capable of delivering adequately high, systemic monoclonal antibody (mAb) concentrations, subcutaneous (SC) injection is arguably the most patient friendly alternative administration route available for this drug class. However, due to the limited volume that can be administered through this route and mAbs' relatively low therapeutic activity, solutions for subcutaneous injection often need to be highly concentrated, making them inherently more prone to potentially detrimental protein (self-) interaction, which is why mAb formulations for SC injection and other highly concentrated mAb solutions are often dried to increase their stability. In this work we investigated spray drying (SD) as a drying technique for formulating mAbs as powders for reconstitution, assessing the influence of SD process parameters, as well as excipients present in the feed solution on both mAb stability and relevant powder characteristics for reconstitution using a model mAb. By employing a design of experiments approach, we were able to provide statistically substantiated evidence for the reconstitution time reducing and stability improving properties of l-arginineHCl, l-histidineHCl, l-lysineHCl and polysorbate 20 when combined with a disaccharide in SD mAb powders for reconstitution. Additionally, the study yielded several statistical models describing process parameter influences on relevant powder and mAb stability characteristics. ispartof: European Journal of Pharmaceutics and Biopharmaceutics vol:127 pages:407-422 ispartof: location:Netherlands status: published

To evaluate the feasibility of producing solid dispersions with 3-fluid nozzle spray drying to improve the dissolution behavior of lipophilic drugs, 60 experiments were performed based on a Design of Experiment. Solid dispersions with mannitol as a hydrophilic matrix and diazepam as a model drug with a drug load of 20 wt-% were produced. The variables of the experiments were the water/organic solvent ratio, liquid feed flow, total solid content, atomizing airflow and type of organic solvent (ethanol or ethyl acetate). The responses measured were dissolution rate, yield, actual drug load, particle size and crystallinity of diazepam and mannitol. Increasing water/organic solvent ratio was found to be the main factor for enhancing the dissolution rate. The total solid content of the solutions to be spray dried did not affect any of the responses, which means that processing solutions of high concentrations is possible. The choice of organic solvent did not affect the responses as well, i.e. both the fully water miscible solvent ethanol and the poorly water miscible solvent ethyl acetate could be used which makes this production method highly versatile., published version, peerReviewed

Solid lipid nanoparticles (SLNs) have gained tremendous attraction as carriers for controlled drug delivery. Despite numerous advances in the field, one long-standing historical challenge for their practical applications remains unmet: redispersibility after drying. In this work, a novel design of SLNs using a layer-by-layer (LbL) technique was developed and the formulations were optimized by surface response methodology (Box-Behnken design). To the best of our knowledge, this is the first study reporting the fabrication of SLNs from all natural ingredients in the absence of any synthetic surfactants or coatings. The SLNs were prepared by a combined solvent-diffusion and hot homogenization method, with soy lecithin as natural emulsifier (first layer), followed by the subsequent coating with sodium caseinate (second layer) and pectin (third layer), both of which are natural food biopolymers. The adsorption of pectin coating onto caseinate was reinforced by hydrophobic and electrostatic interactions induced by a pH-driven process along with thermal treatment. The innovative nano spray drying technology was further explored to obtain ultra-fine powders of SLNs. Compared to uncoated or single-layer coated SLNs powders, which showed severe aggregation after spray drying, the well-separated particles with spherical shape and smooth surface were obtained for layer-by-layer (LbL) SLNs, which were redispersible into water without variation of dimension, shape and morphology. The SLNs were characterized by Fourier transform infrared and high-performance differential scanning calorimetry for their physical properties. The LbL-coated SLNs based on all natural ingredients have promising features for future applications as drug delivery systems, overcoming the major obstacles in conventional spray drying and redispersing SLNs-based formulations.

Antibiotic therapy for a direct administration to the lung in cystic fibrosis patients has to provide suitable availability, possibly in the lower respiratory tract, characterized by the presence of thick secretions. One of the crucial steps in the therapeutic management of the respiratory disease could be the drug solubilization directly in this site of action. The aim of the study was to prepare respirable powders of clarithromycin, while improving drug aqueous solubility. With this aim, several batches of micronized particles were prepared by spray drying different feed solutions, varying the solvent composition (water/isopropyl alcohol ratio), the drug concentration and pH of the liquid feeds. Particle size distribution of raw materials and engineered particles was determined using a light-scattering laser granulometer while particle morphology was assessed by scanning electron microscopy. The in vitro deposition of the micronized clarithromycin powders was evaluated by means of a Single-Stage Glass Impinger using the RS01 model7 by Plastiape® as device for the aerosolization. Solubility measurements of raw and spray-dried (SD) drug were carried out at 37°C in phosphate buffer (0.05M, pH 6.8). Results indicate that morphology and aerodynamic properties of SD particles were strongly influenced by organic solvent concentration and pH of the liquid feeds processed, both modifying drug solubility. Spherical particles and crystals were obtained at higher pH and lower organic solvent content, while wrinkled particles with very interesting aerodynamic properties and higher drug solubility were obtained at lower pH values. Thanks to a fine tuning of the process parameters and liquid feed composition, we produced SD powders with good aerodynamic properties, without using any excipients. Furthermore, SD powders of clarithromycin hydrochloric salt showed higher activity against Pseudomonas aeruginosa growth, compared to clarithromycin raw material.

This work describes uniform polymer coatings allowing for an adjustment of the orifice dimension of vibrating-mesh nozzles and therefore, size of emerging formulation droplets and dried particles, which is of general interest for diverse spray-drying applications. Chemical vapor deposition of poly(p-xylylene) (PPXN) on aperture templates of the B-90 spray-dryer (orifice diameters: ∼4.0μm) caused a reduction of the opening cross-sections of ∼50%. Thus, a more efficient formulation atomization was observed (finer droplets). Likewise, application of PPXN-coated, rather than plain nozzles, resulted in significantly smaller (particle diameter: 1.3 vs. 3.6μm) and narrower distributed (span: ∼1.4 vs. ∼1.8) sildenafil-loaded poly(lactide-co-glycolide) microparticles. Prediction of the size of spray-dried microparticles using the size results of atomized droplets ("residual core method") was shown to be in agreement with the observed values. Formulations prepared with plain and PPXN-coated nozzles exhibited a sustained sildenafil release profile with mean dissolution times of ∼1.5 and ∼4.0h, respectively. Regardless of the starting aperture template, any desired orifice dimension and therefore, dried particle size could be achieved by generating adequate polymer deposits.

In this study, we evaluated the influence of supercritical carbon dioxide (scCO2) spray drying conditions, in the absence of organic solvent, on the ability to produce dry protein/trehalose formulations at 1:10 and 1:4 (w/w) ratios. When using a 4 L drying vessel, we found that decreasing the solution flow rate and solution volume, or increasing the scCO2 flow rate resulted in a significant reduction in the residual water content in dried products (Karl Fischer titration). The best conditions were then used to evaluate the ability to scale the scCO2 spray drying process from 4 L to 10 L chamber. The ratio of scCO2 and solution flow rate was kept constant. The products on both scales exhibited similar residual moisture contents, particle morphologies (SEM), and glass transition temperatures (DSC). After reconstitution, the lysozyme activity (enzymatic assay) and structure (circular dichroism, HP-SEC) were fully preserved, but the sub-visible particle content was slightly increased (flow imaging microscopy, nanoparticle tracking analysis). Furthermore, the drying condition was applicable to other proteins resulting in products of similar quality as the lysozyme formulations. In conclusion, we established scCO2 spray drying processing conditions for protein formulations without an organic solvent that holds promise for the industrial production of dry protein formulations.

The aim of the study was to prepare molecular dispersions of a physically highly unstable amorphous drug, paracetamol (acetaminophen with a T(g) of ca. 25°C) via co-spray drying with a variety of polymers. Solid dispersions at a range of drug loadings (10-90%w/w) using hydroxypropyl methylcellulose/acetate succinate (HPMC/HPMC AS), polyvinylpyrrolidone (PVP) and copovidone were produced and characterised by modulated temperature differential scanning calorimetry (MTDSC), thermogravimetric analysis (TGA), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). PVP-based polymers showed a greater tendency than the HPMC-based group to generate temperature-stable dispersions. In particular, copovidone (Plasdone® S-630) was found to be the most effective of the polymers studied and could formulate molecular dispersions at drug loadings up to and including 40%w/w. However, no evidence for direct drug-polymer interactions was found for such systems as a possible stabilising mechanism. The expected relationship of a higher T(g) of the polymer leading to greater stabilisation was not observed, while there was an inverse relationship between viscosity grade and amorphous phase generation. The study has therefore shown that temperature-stable amorphous dispersions of a low T(g) drug may be prepared by co-spray drying, particularly using PVP-based polymers.

The aim of this study was to prepare novel Zn(2+)-cross-linked alginate microparticles for controlled pulmonary delivery of protein drugs via a simple one-step spray-drying process and to physicochemically characterize these systems. Microparticles were prepared by spray-drying aqueous alginate solutions, containing the model protein BSA, Zn(NH(3))(4)SO(4), and optionally additional excipients. Upon ammonia evaporation, the alginate was cross-linked by Zn(2+)-ions. The microparticles were characterized by SEM, laser and X-ray diffraction, gel electrophoresis, aerodynamic particle size, and drug release measurements. Particles in a size range suitable for deep lung administration were obtained. Pure alginate microparticles were spherical in shape, whereas the addition of zinc led to a more collapsed geometry. Protein release depended on the (i) alginate:ZnSO(4) ratio (minimum release rate at 2:1); (ii) BSA content (decreasing release rate and extent with decreasing BSA content); (iii) type of release medium (increasing release rate with increasing phosphate concentration). The emitted microparticle dose was high for all formulations (∼90%). Fine particle fractions (FPF, depositing in the deep lung) up to 40% could be achieved. The FPF was affected by the BSA content, alginate:ZnSO(4) ratio and presence/absence of poloxamer. Thus, novel Zn(2+)-cross-linked alginate microparticles were prepared via a simple one-step process, providing an interesting potential for controlled pulmonary delivery of proteins.

Strangles is an extremely contagious and sometimes deadly disease of the Equidae. The development of an effective vaccine should constitute an important asset to eradicate this worldwide infectious disease. In this work, we address the development of a mucosal vaccine by using a Supercritical Enhanced Atomization (SEA) spray-drying technique. Aqueous solutions containing the Streptococcus equi extracts and chitosan were converted into nanospheres with no use of organic solvents. The immune response in a mouse model showed that the nanospheres induced a well-balanced Th1 and Th2 response characterized by a unitary ratio between the concentrations of IgG2a and IgG1, together with IgA production. This strategy revealed to be an effective alternative for immunization against S. equi, and therefore, it may constitute a feasible option for production of a strangles vaccine.

The aim of the present work was to develop dry powders containing naringin for a direct administration to the lung to combat oxidative stress. Naringin microparticles were prepared by spray-drying the neat flavonoid (2-5% w/v) from different water/ethanol co-solvents. The spray-dried powders were characterised for morphology, density, particle size distribution, residual humidity, crystallinity, solubility, thermal behaviour and respirable fraction. The fine fraction of the powders was measured by single-stage glass impinger and Andersen cascade impactor, using the Turbospin device for the deposition tests, wherein the dose to be aerosolised was premetered in a gelatine capsule. By increasing the ethanol content, the feed liquid turned from a suspension into a solution: the spray of flavonoid suspensions led to powders with high crystallinity degree, low water solubility and high bulk density, while the spray of drug solutions led to more amorphous particles, with higher solubility, lower density and improved aerodynamic behaviour. The optimisation of the operative parameters produced enhanced aerosol performance of the flavonoid powders containing only the active compound.

Several techniques were compared for improving the dissolution of fenofibrate, a poorly soluble drug. Particle size reduction was realized by jet milling (micronization; cogrinding with lactose, polyvinylpyrrolidone or sodium lauryl sulphate) and by media milling using a bead mill (nanosizing) with subsequent spray-drying. Solid state characterization by X-ray diffraction and Differential Scanning Calorimetry verified the maintenance of the crystalline state of the drug after dry milling and its conversion to the amorphous state during spray-drying. Micronization of fenofibrate enhanced its dissolution rate in biorelevant media (8.2% in 30min) compared to crude material (1.3% in 30min). Coground mixtures of the drug increased the dissolution rate further (up to 20% in 30min). Supersaturated solutions were generated by nanosizing combined with spray-drying, this process converted fenofibrate to the amorphous state. Fenofibrate drug products commercially available on the German and French markets dissolved similarly to crude or micronized fenofibrate, but significantly slower than the coground or spray-dried fenofibrate mixtures. The results suggest that cogrinding and spray-drying are powerful techniques for the preparation of rapidly dissolving formulations of fenofibrate, and could potentially lead to improvements in the bioavailability of oral fenofibrate products.

The effect of maltodextrins and superdisintegrants on the tablet properties was evaluated in directly compressible powders coprocessed via spray drying. Powder mixtures containing acetaminophen, mannitol, erythritol and different maltodextrin types were prepared via co-spray drying and physically mixed with crospovidone (6% w/w, Kollidon CL) in order to evaluate the influence of maltodextrin grade (amylose/amylopectin ratio) on powder hygroscopicity, flowability, density and compactability. In addition, different superdisintegrant types and grades (6% w/w) were co-spray dried to evaluate their effect on tablet disintegration time. Tablet disintegration was affected by the amylose/amylopectin ratio of the maltodextrins. Tablets containing Glucidex 2 (1-5% amylose) had a longer disintegration time compared to Glucidex 9 (20% amylose) (11.8min versus 5.7min) and Unipure DC (50-70% amylose) (1min). The disintegration time of tablets containing a coprocessed superdisintegrant was long due to loss of superdisintegrant during processing (preferential depositing on the spray dryer wall) and was in the following order: Kollidon CL

Inhalation of spray-dried particles is a promising delivery route for proteins as an alternative to injection. Changes in the protein structure and aggregation have to be avoided. The effect of mannitol, a stabilizing agent typically used in both liquid and lyophilized protein formulations, on an antibody (IgG1) in a spray-dried powder was studied using different biophysical and chromatographic techniques. At first, different solutions composed of antibody (IgG1) and mannitol at a ratio between 20/80 and 100/0 IgG1/mannitol (100 mg/ml total solid) were investigated for their stability. Protein solutions containing the IgG1 showed mannitol-dependent aggregation. High amounts of mannitol (50-80%) exerted a destabilizing effect on the antibody and the aggregate 9 level increased to 2.6-4.2%. In contrast, solutions with only 20-40% mannitol showed the same amount of aggregates as the pure antibody solution. The antibody mannitol solutions were investigated by circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR) to evaluate whether changes in the protein secondary structure can be correlated with aggregation. Considering the sensitivity of the used methods and data evaluation, FTIR spectra did not reveal structural changes in the IgG1/mannitol solutions compared to the pure antibody, despite varying aggregate levels. Thermal stress was reflected in perturbations of the secondary structure, but mannitol-dependent aggregation could not be correlated to detectable alterations in the FTIR spectra. Analyzing the CD spectra revealed no distinctive change in the shape of the CD curve, indicating that the protein secondary structure is mainly retained. This is in agreement with the infrared data. Subsequently, the IgG1/mannitol solutions were spray-dried at Tin/Tout of 90/50 degrees C. Using ATR-FTIR for the investigation of the protein amide I band in the spray-dried powder revealed changes in the sub-components of the amide I band. This indicates that the peptide groups (CO and NH) of the protein are found in a different environment in the solid state, compared to the liquid protein formulation. After redissolution of the powders, the native structure of the pure antibody solution was found identical to the protein secondary structure before spray-drying, indicating that the protein secondary structure is not strongly altered in the dry state, and not affected by the spray-drying process. Thus, from the presented study it can be concluded that the formation of antibody aggregates in mannitol formulations cannot be correlated with significant perturbations of the protein secondary structure elements.

This study aims to develop and characterise a beclomethasone diproprionate:gamma-cyclodextrin (BDP:gamma-CYD) complex and to optimise the variables on the spray-drying process, in order to obtain a powder with the most suitable characteristics for lung delivery. The spray-dried powder--in a mass ratio of 2:5 (BDP:gamma-CYD)--was physically mixed with three carriers of different particle sizes and in different ratios. Particle-size distribution, shape and morphology, moisture content, and uniformity in BDP content of formulations were studied. In vitro aerolisation behaviour of the formulations was evaluated using the Rotahaler, and the performance was characterised based on the uniformity of emitted dose and aerodynamic particle-size distribution (respirable fraction (RF), as a percentage of nominal dose (RFN) and emitted dose (RFE)). The most suitable conditions for the preparation of BDP:gamma-CYD complexes were obtained with the solution flow of 5 ml/min, T(in) of 70 degrees C and T(out) of 50 degrees C. Statistically significant differences in the aerodynamic performances were obtained for formulations containing BDP:gamma-CYD complexes prepared using different solution flows and different T(in) (p

Quality by design (QBD) refers to a holistic approach towards drug development. Important parts of QBD include definition of final product performance and understanding of formulation and process parameters. Inhalation of proteins for systemic distribution requires specific product characteristics and a manufacturing process which produces the desired product. The objective of this study was to understand the spray drying process of insulin intended for pulmonary administration. In particular, the effects of process and formulation parameters on particle characteristics and insulin integrity were investigated. Design of experiments (DOE) and multivariate data analysis were used to identify important process parameters and correlations between particle characteristics. The independent parameters included the process parameters nozzle, feed, and drying air flow rate and drying air temperature along with the insulin concentration as a formulation parameter. The dependent variables included droplet size, geometric particle size, aerodynamic particle size, yield, density, tap density, moisture content, outlet temperature, morphology, and physical and chemical integrity. Principal component analysis was performed to find correlations between dependent and independent variables. Prediction equations were obtained for all dependent variables including both interaction and quadratic terms. Overall, the insulin concentration was found to be the most important parameter, followed by inlet drying air temperature and the nozzle gas flow rate. The insulin concentration mainly affected the particle size, yield and tap density, while the inlet drying air temperature mainly affected the moisture content. No change was observed in physical and chemical integrity of the insulin molecule.

Sustained-release of buspirone HCl (BUH) was attempted by spray drying after dissolving in two commercially available aqueous polymeric dispersions (Eudragit ® RS 30 D or Kollicoat ® SR 30 D) at five different drug:polymer ratios (1:1, 1:2, 1:3, 1:6 and 1:9). The produced spray-dried agglomerates were evaluated in terms of their particle size and morphology, production yield, encapsulation efficiency and in-vitro release of BUH. Possible drug–polymer interactions were checked by Differential Scanning Calorimetry (DSC) and FT-IR spectroscopy. Scanning electron microscopy (SEM) was employed for the qualitative characterization of particle size and morphology. Encapsulation efficiency was generally high (around 100%) and independent of the polymeric dispersion type, while production yield was generally low (7.2–31.0%) and significantly lower for the case of Kollicoat SR 30 D (KSR) than for Eudragit RS 30 D (ERS). Scanning electron micrographs showed remarkable changes in size and shape of agglomerates due to the type of aqueous polymeric dispersion and drug:polymer ratio. In-vitro release of BUH from compacted co spray-dried agglomerates was remarkably slower and incomplete for the case of Kollicoat ® at drug:polymer ratio below 1, presumably due to increased plastic deformation of the developed coating instead of fragmentation in the case of Eudragit ® coating during compaction.

An immunoglobulin G (IgG) was spray-dried on a Buchi 190 laboratory spray-dryer at inlet and outlet air temperatures of 130 and 190 degrees C, respectively. The IgG solution contains initially 115 mg/ml IgG plus 50 mg/ml sorbitol. After dialysis, at least 80% of low molecular weight component was removed. After spray-drying the dialyzed IgG and immediate redissolution of the powder, an increase in aggregates from 1 to 17% occurred. A major shift towards increase beta-sheet structure was detected in the spray-dried solid, which, however, reverted to native structure on redissolution of the powder. A correlation between aggregation determined by size exclusion chromatography and alterations in secondary structure determined by Fourier transformation infra-red spectroscopy could not therefore be established. On spray-drying a non-dialyzed, sorbitol-containing IgG only some 0.7% aggregates were formed. The sorbitol is therefore evidently able to stabilize partially the IgG during the process of spray-drying. Addition of trehalose to the liquid feed produced quantitatively the same stabilizing action on the IgG during spray-drying as did the sorbitol. This finding again points towards a water replacement stabilization mechanism. The IgG spray-dried powder prepared from the dialyzed liquid feed showed continued substantial aggregation on dry storage at 25 degrees C. This was substantially less in the non-dialyzed, sorbitol-containing spray-dried powder. Addition of trehalose to both dialyzed and non-dialyzed system produced substantial improvement in storage stability and reduction in aggregate formation in storage. The quantitative stabilizing effect of the trehalose was only slightly higher than that of the sorbitol. Taken together, these results indicate that both the sorbitol and trehalose stabilize the IgG primarily by a water replacement mechanism rather than by glassy immobilization. The relevance of this work is its questioning of the importance of the usually considered dominance of glassy stabilization of protein in dried systems of high glass transition temperature, such as trehalose. The low glass transition temperature sorbitol produces almost equal process and storage stability in this case.

In order to improve the in vitro performance and stability of co-spray-dried itraconazole/Inutec SP1 systems, the influence of adding PVPVA 64, a polymer that is compatible with itraconazole, was evaluated. Dissolution tests were carried out on several itraconazole/PVPVA 64/Inutec SP1 compositions and spray-dried itraconazole/PVPVA 64 powders were used as references. The physicochemical properties of the samples were assessed with modulated temperature differential scanning calorimetry (MDSC), X-ray powder diffraction (XRD) and environmental scanning electron microscopy (ESEM). Physicochemical analysis revealed that there is no interaction between itraconazole and Inutec SP1 and that sufficient amount of PVPVA 64 is required to keep the drug molecularly dispersed. The improvement of the ternary solid dispersions over the binary solid dispersions was composition dependent. On one hand the increased drug/PVPVA 64 ratio in the ternary systems slowed dissolution down, on the other hand this was compensated by the solubilizing power of Inutec SP1.

Poly(d,l-lactic-co-glycolic acid) (PLGA) microparticles encapsulating therapeutic proteins were prepared under a water-free formulation condition. Bovine serum albumin (BSA) and recombinant human growth hormone (rhGH) were homogeneously solubilized as nano-scale complexes in methylene chloride phase by using polyethylene glycol (PEG) as a complex-forming agent. The organic phase containing dissolved PLGA and PEG/protein complexes was directly spray dried to obtain PLGA microparticles encapsulating proteins. They exhibited sustained release profiles of BSA and rhGH up to 30 days with reduced initial bursts. The released protein molecules from the microparticles maintained structural integrity without aggregation, suggesting that the current single-step protein microencapsulation method without using water could be potentially applied for sustained delivery of a wide range of therapeutic protein drugs that are not soluble in organic solvents.

Solid dispersions of PEG6000 and loperamide-a poorly water-soluble agent-were prepared by spray drying. Their physicochemical properties were evaluated immediately after preparation. The dissolution was higher than that of pure crystalline loperamide. DSC- and XRD-measurements revealed that in the dispersions, loperamide is partially present in the crystalline state. A eutectic state diagram was obtained. The samples containing 20% loperamide were stored under different conditions (40 degrees C and 0% RH, 25 degrees C and 52% RH, 4 degrees C and 0% RH) to investigate their stability as a function of time. The dissolution properties deteriorate upon storage at high temperature (40 degrees C and 0% RH) and in conditions of higher relative humidity (25 degrees C and 52% RH). The DSC-curves clearly indicate an increase in the amount of crystalline compound under these conditions. From these observations it could be concluded that loperamide, which is partially crystalline and partially amorphous in the freshly prepared samples, continues to crystallize under these conditions, resulting in progressively poorer dissolution properties.

The aim of this study was an in vitro/in vivo investigation on poly(lactide-co-glycolide) (PLGA) microspheres as carriers for the topical ocular delivery of a peptide drug vancomycin (VA). The microspheres were prepared by an emulsification/spray-drying technique that can be proposed as an alternative to the double emulsion method for preparation of peptide-loaded microparticles. The drug encapsulation efficiencies were close to the theoretical values (84.2-99.5%); the average particle size, expressed as dvs, was about 11 microm. The microspheres were able to modulate the in vitro drug release of VA with a behavior dependent on their composition: the highest drug content corresponded to the highest release rate. In vivo studies were carried out by assessing the pharmacokinetic profile of VA in the aqueous humor of rabbits after topical administration of aqueous suspensions of microspheres. High and prolonged VA concentrations and increased AUC values (2-fold) with respect to an aqueous solution of the drug were observed. Increasing the viscosity of the microsphere suspension by addition of a suspending-viscosizing agent (hydroxypropylcellulose) did not produce an increase of the ocular bioavailability. PLGA microspheres can be proposed as a system for ocular delivery of peptide drugs.

Aqueous dispersions of solid lipid nanoparticles (SLNTM) were converted by spray-drying into dry, reconstitutable powders which could be stored over a long period. After redispersion, the resulting granulates were still acceptable for i.v. administration with respect to the particle size distribution and toxicity. Therefore only physiologically-acceptable excipients such as carbohydrates and alcohols (ethanol and methanol) were added to the SLN dispersions before spraying. The particle size was influenced by the applied spraying parameters and by the chemical nature of the lipid phase, the type of carbohydrate and the spraying, and the redispersion medium. An identical size distribution before and after the spraying process, followed by subsequent redispersion was achieved by: reducing the temperature by spraying alcoholic dispersions, reducing the lipid concentration while increasing the sugar concentration, and by redispersion in a poloxamer 188 solution.

From a quality by design perspective, the aim of the present study was to demonstrate the applicability of a Bayesian statistical methodology to identify the Design Space (DS) of a spray-drying process. Following the ICH Q8 guideline, the DS is defined as the "multidimensional combination and interaction of input variables (e.g., materials attributes) and process parameters that have been demonstrated to provide assurance of quality." Thus, a predictive risk-based approach was set up in order to account for the uncertainties and correlations found in the process and in the derived critical quality attributes such as the yield, the moisture content, the inhalable fraction of powder, the compressibility index, and the Hausner ratio. This allowed quantifying the guarantees and the risks to observe whether the process shall run according to specifications. These specifications describe satisfactory quality outputs and were defined a priori given safety, efficiency, and economical reasons. Within the identified DS, validation of the optimal condition was effectuated. The optimized process was shown to perform as expected, providing a product for which the quality is built in by the design and controlled setup of the equipment, regarding identified critical process parameters: the inlet temperature, the feed rate, and the spray flow rate.