Survival of Beijerinckia sp. microencapsulated in carbohydrates by spray-drying

The encapsulation of Beijerinckia sp. cell suspension in different wall materials using the spray drying technique was performed. Mat dextrin, dehydrated glucose syrups, gum acacia and modified starch materials were tested. Cell viability assays were carried out before and after drying and during storage of the products. The surface area and characteristics of the encapsulated powders were examined using BET adsorption of N₂ and scanning electron microscopy, respectively. The residual moisture content and water activity of the powders were also determined. The best results were obtained with the dehydrated glucose syrup, which resulted in products with the greatest per cent survival during the drying process and subsequent storage period. The products obtained with the dehydrated glucose syrup showed more uniform microcapsule surfaces at lower A_w values and residual moisture content.     

Effect of Spray Drying and Subsequent Processing Conditions on Residual Moisture Content and Physical/Biochemical Stability of Protein Inhalation Powders

Purpose. To understand the effect of spray drying and powder processing environments on the residual moisture content and aerosol performance of inhalation protein powders. Also, the long-term effect of storage conditions on the powder's physical and biochemical stability was presented. Methods. Excipient-free as well as mannitol-formulated powders of a humanized monoclonal antibody (anti-IgE) and recombinant human deoxyribonuclease (rhDNase) were prepared using a Buchi 190 model spray dryer. Residual moisture content and moisture uptake behavior of the powder were measured using thermal gravimetric analysis and gravimetric moisture sorption isotherm, respectively. Protein aggregation, the primary degradation product observed upon storage, was determined by size-exclusion HPLC. Aerosol performance of the dry powders was evaluated after blending with lactose carriers using a multi-stage liquid impinger (MSLI). Results. Spray-dried powders with a moisture level (~ 3%) equivalent to the freeze-dried materials could only be achieved using high-temperature spray-drying conditions, which were not favorable to large-male manufacturing, or subsequent vacuum drying. These dry powders would equilibrate with the subsequent processing and storage environments regardless of the manufacturing condition. As long as the relative humidity of air during processing and storage was lower than 50%, powders maintained their aerosol performance (fine particle fraction). However, powders stored under drier conditions exhibited better long-term protein biochemical stability. Conclusions. Manufacturing, powder processing, and storage environments affected powder's residual moisture level in a reversible fashion. Therefore, the storage condition determined powder's overall stability, but residual moisture had a greater impact on protein chemical stability than on powder physical stability.     

Suitability of differently formulated dry powder Newcastle disease vaccines for mass vaccination of poultry

Dry powders containing a live-attenuated Newcastle disease vaccine (LZ58 strain) and intended for mass vaccination of poultry were prepared by spray drying using mannitol in combination with trehalose or inositol, polyvinylpyrrolidone (PVP) and/or bovine serum albumin (BSA) as stabilizers. These powders were evaluated for vaccine stabilizing capacity during production and storage (at 6 °C and 25 °C), moisture content, hygroscopicity and dry powder dispersibility. A mixture design, varying the ratio of mannitol, inositol and BSA, was used to select the stabilizer combination which resulted in the desired powder properties (i.e. good vaccine stability during production and storage, low moisture content and hygroscopicity and good dry dispersibility). Inositol-containing powders had the same vaccine stabilizing capacity as trehalose powders, but were less hygroscopic. Incorporation of BSA enhanced the vaccine stability in the powders compared to PVP-containing formulations. However, increasing the BSA concentration increased the hygroscopicity and reduced the dry dispersibility of the powder. No valid mathematical model could be calculated for vaccine stability during production or storage, but the individual experiments indicated that a formulation combining mannitol, inositol and BSA in a ratio of 73.3:13.3:13.3 (wt/wt) resulted in the lowest vaccine titre loss during production (1.6-2.0 log(10) 50% egg infectious dose (EID(50)) and storage at 6 °C (max. 0.8 log(10) EID(50) after 6 months) in combination with a low moisture content (1.1-1.4%), low hygroscopicity (1.9-2.1% water uptake at 60% relative humidity) and good dry dispersibility properties.     

Effects of emulsification and microencapsulation on the oxidative stability of camelina and sunflower oils

Oil-in-water (O/W) emulsions were prepared using different concentrations of camelina or sunflower oil. Sodium caseinate was used as the emulsifier and dried glucose syrup as the wall material. Emulsions were subsequently spray dried to yield high-fat powders (71.7–85.0%). Emulsification and microencapsulation of bulk oils decreased their level of lipid oxidation (lipid hydroperoxide and p-Anisidine values, p-Avs). Sunflower oil, O/W emulsions and reconstituted powders generally had lower oxidation products than corresponding camelina oil-based products throughout storage at 15°C. p-Avs of bulk oils remained constant, whereas p-Avs of O/W emulsions and reconstituted powders decreased early in storage, and remained low thereafter. Microencapsulated omega (ω)-3 rich powders were produced, easily reconstituted and showed no signs of deterioration throughout storage. These powders provided functional properties with potential for incorporation into various food systems as a source of beneficial ω-3 fatty acids.     

Effect of stopper processing conditions on moisture content and ramifications for lyophilized products: comparison of "low" and "high" moisture uptake stoppers

The purpose of this study was to evaluate the effect of processing and storage on the moisture content of two commercially available, 13-mm lyophilization stoppers designated as low moisture (LM) and high moisture (HM) uptake stoppers. The stopper moisture studies included the effect of steam sterilization time, drying time and temperature, equilibrium moisture content, lyophilization and moisture transfer from stopper to a model-lactose lyophilized cake. Results indicated that both stoppers absorbed significant amounts of moisture during sterilization and that the HM stopper absorbed significantly more water than the LM stopper. LM and HM stoppers required approximately 2 and 8 h drying at 105 degrees C, respectively, to achieve final moisture content of not more than 0.5 mg/stopper. Following drying, stopper moisture levels equilibrated rapidly to ambient storage conditions. The apparent equilibrium moisture level was approximately 7 times higher in the HM versus LM stopper. Freeze-drying had minimal effect on the moisture content of dried stoppers. Finally, moisture transfer from the stopper to the lyophilized product is dependent on the initial stopper water content and storage temperature. To better quantify the ramifications of stopper moisture, projections of moisture uptake over the shelf life of a drug product were calculated based on the product-contact surface area of stoppers. Attention to stopper storage conditions prior to use, in addition to processing steps, are necessary to minimize stability issues especially in low-fill, mass lyophilized products.     

Impact of Different Elastomer Formulations on Moisture Permeation through Stoppers Used for Lyophilized Products Stored under Humid Conditions

The purpose of this study was to evaluate the effect of moisture permeability of different elastomer formulation stoppers, which had different moisture absorption abilities, on the increase of moisture content inside lyophilized vials during long-term storage under humid conditions. Two different elastomer formulation stoppers (high-moisture and low-moisture uptake stoppers) were compared. The increased amount of moisture content inside lyophilized vials fitted with high-moisture stoppers was higher than those fitted with low-moisture stoppers during the early stage of storage. However, this trend was reversed during the later stage of storage. Our data show that the moisture increase inside the lyophilized vials at the early stage was caused by moisture transfer from the stoppers, whereas the later moisture increase was caused by external moisture permeation through the stoppers. Results indicate that the difference in the moisture uptake profile inside the lyophilized vials at each period of storage was caused by the moisture absorption ability and moisture permeation ability of the two elastomer formulation stoppers. In terms of long-term storage stability under humid conditions, our data indicate that external moisture permeating through the stopper into the lyophilized vial during the late stage was the more important factor. In addition, the increase in moisture content at the early stage was controlled by stopper drying time. Furthermore, stopper drying time did not have an effect on moisture permeation at the late stage. Moisture permeation during the storage period appears to be dependent on the different elastomer formulations of the stoppers. The moisture permeation of different elastomer stoppers was an important factor in terms of the increased moisture content inside the lyophilized vials during the late stage of long-term storage under humid conditions. For lyophilized products stored at room temperature, the moisture permeation ability of the stopper is one of the most important factors for long-term storage stability.     

Monitoring of the Secondary Drying in Freeze-Drying of Pharmaceuticals

This paper is focused on the in-line monitoring of the secondary drying phase of a lyophilization process. An innovative software sensor is presented to estimate reliably the residual moisture in the product and the time required to complete secondary drying, that is, to reach the target value of the residual moisture or of the desorption rate. Such results are obtained by coupling a mathematical model of the process and the in-line measurement of the solvent desorption rate and by means of the pressure rise test or another sensors (e.g., windmills, laser sensors) that can measure the vapor flux in the drying chamber. The proposed method does not require extracting any vial during the operation or using expensive sensors to measure off-line the residual moisture. Moreover, it does not require any preliminary experiment to determine the relationship between the desorption rate and residual moisture in the product. The effectiveness of the proposed approach is demonstrated by means of experiments carried out in a pilot-scale apparatus: in this case, some vials were extracted from the drying chamber and the moisture content was measured to validate the estimations provided by the soft-sensor.     

Moisture and drug solid-state monitoring during a continuous drying process using empirical and mass balance models

Classically, the end point detection during fluid bed drying has been performed using indirect parameters, such as the product temperature or the humidity of the outlet drying air. This paper aims at comparing those classic methods to both in-line moisture and solid-state determination by means of Process Analytical Technology (PAT) tools (Raman and NIR spectroscopy) and a mass balance approach. The six-segmented fluid bed drying system being part of a fully continuous from-powder-to-tablet production line (ConsiGma™-25) was used for this study. A theophylline:lactose:PVP (30:67.5:2.5) blend was chosen as model formulation. For the development of the NIR-based moisture determination model, 15 calibration experiments in the fluid bed dryer were performed. Six test experiments were conducted afterwards, and the product was monitored in-line with NIR and Raman spectroscopy during drying. The results (drying endpoint and residual moisture) obtained via the NIR-based moisture determination model, the classical approach by means of indirect parameters and the mass balance model were then compared. Our conclusion is that the PAT-based method is most suited for use in a production set-up. Secondly, the different size fractions of the dried granules obtained during different experiments (fines, yield and oversized granules) were compared separately, revealing differences in both solid state of theophylline and moisture content between the different granule size fractions.     

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.     

Physical characteristics and aerosolization performance of insulin dry powders for inhalation prepared by a spray drying method

The objective of this study was to investigate the influence of formulation excipients on the physical characteristics and aerosolization performance of insulin dry powders for inhalation. Insulin dry powders were prepared by a spray drying technique using excipients such as sugars (trehalose, lactose and dextran), mannitol and amino acids (L-leucine, glycine and threonine). High performance liquid chromatography and the mouse blood glucose method were used for determination of the insulin content. The powder properties were determined and compared by scanning electron microscopy, thermo-gravimetric analysis and size distribution analysis by a time-of-flight technique. The in-vitro aerosolization behaviour of the powders was assessed with an Aerolizer inhaler using a twin-stage impinger. Powder yield and moisture absorption were also determined. Results showed that there was no noticeable change in insulin content in any of the formulations by both assay methods. All powders were highly wrinkled, with median aerodynamic diameters of 2-4 microm, and consequently suitable for pulmonary administration. The tapped density was reduced dramatically when glycine was added. The powders containing mannitol, with or without L-leucine, were less sensitive to moisture. The highest respirable fraction of 67.3 +/- 1.3% was obtained with the formulation containing L-leucine, in contrast to formulations containing glycine and threonine, which had a respirable fraction of 11.2 +/- 3.9% and 23.5 +/- 2.5%, respectively. In addition, powders with good physical properties were achieved by the combination of insulin and trehalose. This study suggests that L-leucine could be used to enhance the aerosolization behaviour of the insulin dry powders for inhalation, and trehalose could potentially be used as an excipient in the formulations.     

Effects of Moisture Content on the Storage Stability of Dried Lipoplex Formulations

The purpose of this study is to investigate the effects of moisture content on the storage stability of freeze-dried lipoplex formulations. DC-Cholesterol: DOPE (dioleoyl phosphatidylethanolamine)/plasmid DNA lipoplexes were prepared at a 3-to-2 DC-Cholesterol⁺ to DNA^? molar ratio and lyophilized prior to storing at room temperature, 40, and 60°C for 3 months. Different residual moistures (1.93%, 1.10%, 1.06%, and 0.36%) were obtained by altering the secondary drying temperatures. In addition to moisture content, lipoplex formulations were evaluated after freeze-drying and/ or storage for particle size, transfection efficiency, accumulation of thiobarbituric acid reactive substances (TBARS), glass transition temperature, DNA supercoil content, and surface area. Lipoplex formulations stored at room temperature for 3 months maintain TBARS concentrations and supercoil contents. At higher storage temperatures, formulations possessing the highest moisture content (1.93%) maintained significantly lower TBARS concentrations and higher supercoil content than those with the lowest (0.36%) moisture content. Curiously, the intermediate moisture contents exhibited marked differences in stability despite virtually identical moisture contents. Subsequent measurements of surface area indicated that the lower stability corresponded to higher surface area in the dried cake, suggesting that there may be an interplay between water content and surface area that contributes to storage stability.     

土壤水分对新鲜和采后干燥丹参根中活性成分含量的影响

目的：进一步验证丹参药材中丹酚酸类成分尤其是丹酚酸B是采后干燥的产物;了解栽培过程中土壤水分状态对新鲜和阴干后丹参药材中丹酚酸类和丹参酮类成分的影响。方法采用高效液相色谱法测定了不同土壤水分条件栽培的新鲜和采后阴干丹参样品中6种酚酸类和4种丹参酮类成分的含量。结果新鲜丹参样品中,均含有较高含量丹参酮类成分,但只有极度干旱胁迫时（土壤水势＜30％）,才可检测到丹酚酸B（＜1％）,且无其他酚酸类成分。阴干样品中丹酚酸类成分含量均显著增加,其中丹酚酸B含量达4．2％;丹参酮类成分也增加了30％以上。阴干后丹参中丹酚酸B及总酚酸含量与栽培过程中土壤水势呈现显著负相关。结论采后干燥有利于丹参中活性成分积累。丹参药材中丹酚酸类成分尤其是丹酚酸B是栽培和采后极度干旱（干燥）的产物,栽培过程中适度的干旱胁迫有利于药材中酚酸类成分的产生。     

Preparation of redispersible dry nanocapsules by means of spray-drying: development and characterisation.

Nanoparticles suspensions very often present a physicochemical instability during their storage. In order to overcome this lack of stability and facilitate the handling of these colloidal systems, the water elimination from the aqueous dispersions to obtain a dry solid form appears as the most promising strategy. The present paper reports the use of the spray-drying technique for the nanocapsules (NC) suspensions conversion into redispersible dried solid particles in presence of different water-soluble excipients as drying auxiliaries. Following the combination of additives solutions with NC suspension, the final dispersion homogeneity was favoured, avoiding phase separations. According to the size measurement after a simple atomisation experiment, the NC, which have a thin and fragile shell structure can withstand the shear forces developed for the feed disintegration in droplets. During drying, certain additives molecules are able to act as NC protectors. The physicochemical characterization of the spray-dried powders included an investigation of their properties, such as residual moisture content, particulate density, morphology and redispersion in water. Using a NC concentration of 1% (w/v), the best result was obtained with the preparation containing 10% (w/v) of lactose which led to more desirable powder morphology and favouring NC suspension reconstitution with only approximately 2% of the size distribution in the micrometer range. The spray-drying technique is an attractive method to improve the NC conservation and facilitate future handling.     

Dehydration studies using a novel multichamber microscale fluid bed dryer with in-line near-infrared measurement

The purpose of this research was to study the effect of two process parameters (temperature and moisture content) on dehydration behavior of different materials using a novel multichamber microscale fluid bed dryer with a process air control unit and in-line near-infrared (NIR) spectroscopy. The materials studied were disodium hydrogen phosphates with three different levels of hydrate water and wet theophylline granules. Measured process parameters of fluid bed drying were logged, including in-line NIR signals. Off-line analyses consisted of X-ray powder diffraction patterns, Fourier transform NIR spectra and moisture contents of studied materials. During fluid bed drying, the stepwise dehydration of materials was observed by the water content difference of inlet and outlet air, the pressure difference over the bed, and the in-line NIR spectroscopy. The off-line analysis confirmed the state of solid materials. The temperature and the moisture content of the process air were demonstrated to be significant factors for the solid-state stability of theophylline. The presented setup is a material and cost-saving approach for studying the influence of different process parameters on dehydration behavior during pharmaceutical processing.     

Factors Influencing the Retention of Organic Solvents in Products Freeze-Dried From Co-Solvent Systems

Controlling residual solvent levels is a major concern in pharmaceutical freeze-drying from co-solvent systems. This review provides an overview of the factors influencing this process and estimates their potential to reduce residual solvents in freeze-dried products. Decreased solvent contents are potentially correlated with the lower solid content, complete excipient crystallization, higher water solubility, and smaller molecular sizes of the solvent. Although no general rule can be derived for the selection of appropriate freezing conditions, the freezing stage appears to play a major role in subsequent volatile retention. In contrast, diverse secondary drying conditions do not appear to impact the amount of solvent retained in lyophilisates, and modification of this stage is thus not assumed to be expedient. Co-solvents are strongly entrapped in an amorphous product matrix as soon as the local moisture content decreases below a certain level. Thus, the moisture content in the dried product layer adjacent to the sublimation interface might be a key factor. Therefore, extension of the high moisture content period during the primary drying phase as well as a postlyophilization humidification of the dried products are presumably promising approaches to promote solvent release.     

Feasibility Study on Spray-Drying Protein Pharmaceuticals: Recombinant Human Growth Hormone and Tissue-Type Plasminogen Activator

The feasibility of spray-drying solutions of recombinant methionyl human growth hormone (hGH) and tissue-type plasminogen activator (t-PA) was investigated. hGH was formulated in a mannitol phosphate buffer and t-PA was used in an arginine phosphate formulation containing 0.004% (w/v) polysorbate 80. Using filtered air (90 – 150°C) as the drying medium, hGH could be dried to a residual moisture content of 4%. However, approximately 25% of the protein was degraded during the processing. Results of atomization studies suggest that surface denaturation at the air–liquid interface of the droplets in the spray plays a major role in the degradation of the protein. The addition of 0.1% (w/v) polysorbate 20 into the hGH formulation reduced the formation of soluble and insoluble aggregates by approximately 90% during atomization. During spray-drying the addition of 0.1% (w/v) polysorbate 20 reduced the formation of soluble and insoluble aggregates by approximately 70 and 85%, respectively. In contrast, t-PA remained intact upon atomization. Depending on the spray-drying conditions, product powders with a residual moisture content between 5 and 8% were obtained. No oxidation, aggregation, or denaturation occurred in the protein under several operation conditions. Overall, this study demonstrates that it is feasible to spray-dry t-PA in the current marketed formulation.     

Investigating the effect of dehydration conditions on the compactability of glucose

Hydrates are commonly found in pharmaceutical ingredients either in excipients or in the active pharmaceutical ingredient form. There is always the possibility that the processing involved in manufacturing can result in the dehydration of the hydrate components. It has been seen that different dehydration conditions can have an effect on the behavior of the final product; however this area has not been fully investigated. In this work, glucose monohydrate powder was dehydrated at four different conditions and then compressed to see the effect on the hardness of the compacts. Various analytical tools such as inverse gas chromatography, differential scanning calorimetry, X-ray powder diffractometry and scanning electron microscopy were used to determine any differences in the properties of the dehydrates and correlated with the obtained compact hardness. Annealing studies were performed to determine the effect of storage on the dehydrated materials both before and after compression. It was observed that while annealing of the powders did have an impact, annealing of the compacts did not influence the hardness. The results of the characterization and annealing studies showed that the difference in the behavior of glucose dehydrates were due to the presence of amorphous regions within the particulates.     

Polyethylene glycol-induced precipitation of interferon alpha-2a followed by vacuum drying: Development of a novel process for obtaining a dry, stable powder

Feasibility studies were performed on the development of a novel process based on polyethylene glycol (PEG)-induced precipitation of proteins followed by vacuum drying in the presence of sugars to obtain dry protein powders. Apparent solubility of interferon alpha-2a (IFNalpha2a) was determined in the presence of various PEGs and the effect of solution pH, ionic strength, and temperature was investigated. IFNalpha2a precipitate was dried at a shelf temperature of 25 degrees C at 100 mTorr either as it is or in the presence of mannitol and/or trehalose. The dried IFNalpha2a formulations were subjected to accelerated stability studies at 40 degrees C (3 months), and the stability was compared with that of a similar lyophilized formulation. The results indicated that more than 90% of the protein could be precipitated using 10% wt/vol PEG the protein could be precipitated using 10% wt/vol PEG 1450 at pH 6.5 at a solution ionic strength of 71 mM. Vacuum drying of the precipitate only resulted in the formation of insoluble aggregates of IFNalpha2a; however, this was prevented by the addition of either mannitol or trehalose. The addition of excess mannitol resulted in low residual moisture content and better handling of the final dried product. Accelerated storage stability did not show any aggregation and showed less than 5% formation of oxidized IFNalpha2a in the dried formulation containing IFNalpha2a: trehalose: mannitol in a 1:10:100 wt/wt ratio upon storage at 40 degrees C for 3 months. The stability of this vacuum dried formulation was comparable with that of a similar lyophilized formulation.     

Current Approaches of Preservation of Cells During (freeze-) Drying

The widespread application of therapeutic cells requires a successful stabilization of cells for the duration of transport and storage. Cryopreservation is currently considered the gold standard for the storage of active cells; however, (freeze-) drying cells could enable higher shelf life stability at ambient temperatures and facilitate easier transport and storage.During (freeze-) drying, freezing, (primary and secondary) drying and also the reconstitution step pose the risk of potential cell damage. To prevent these damaging processes, a wide range of protecting excipients has emerged, which can be classified, according to their chemical affiliation, into sugars, macromolecules, polyols, antioxidants and chelating agents. As many excipients cannot easily permeate the cell membrane, researchers have established various techniques to introduce especially trehalose intracellularly, prior to drying.This review aims to summarize the main damaging mechanisms during (freeze-) drying and to introduce the most common excipients with further details on their stabilizing properties and process approaches for the intracellular loading of excipients. Additionally, we would like to briefly explain recently discovered advantages of drying microorganisms, sperm, platelets, red blood cells, and eukaryotic cells, paying particular attention to the drying technique and residual moisture content.