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  • 1
    Electronic Resource
    Electronic Resource
    Generalized couette flow of a non-Newtonian fluid in annuli. Reply to comments (1982)
    s.l. : American Chemical Society
    Industrial and engineering chemistry 21 (1982), S. 98-99 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/i100005a025
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  • 2
    Electronic Resource
    Electronic Resource
    Generalized Couette Flow of a Non-Newtonian Fluid in Annuli (1980)
    s.l. : American Chemical Society
    Industrial and engineering chemistry 19 (1980), S. 421-424 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/i160076a017
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  • 3
    Electronic Resource
    Electronic Resource
    Protein Inhalation Powders: Spray Drying vs Spray Freeze Drying (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 249-254 
    Details
    ISSN: 1573-904X
    Keywords: spray freeze drying ; spray drying ; dispersibility ; fine particle fraction ; liquid impingement ; cascade impaction ; aerodynamic particle size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To develop a new technique, spray freeze drying, for preparing protein aerosol powders. Also, to compare the spray freeze-dried powders with spray-dried powders in terms of physical properties and aerosol performance. Methods. Protein powders were characterized using particle size analysis, thermogravimetric analysis, scanning electron microscopy, X-ray powder diffractometry, and specific surface area measurement. Aerosol performance of the powders was evaluated after blending with lactose carriers using a multi-stage liquid impinger or an Anderson cascade impactor. Two recombinant therapeutic proteins currently used for treating respiratory tract-related diseases, deoxyribonuclase (rhDNase) and anti-IgE monoclonal antibody (anti-IgE MAb), were employed and formulated with different carbohydrate excipients. Results. Through the same atomization but the different drying process, spray drying (SD) produced small (∼3 μm), dense particles, but SFD resulted in large (∼8−10 μm), porous particles. The fine particle fraction (FPF) of the spray freeze-dried powder was significantly better than that of the spray-dried powder, attributed to better aerodynamic properties. Powders collected from different stages of the cascade impactor were characterized, which confirmed the concept of aerodynamic particle size. Protein formulation played a major role in affecting the powder's aerosol performance, especially for the carbohydrate excipient of a high crystallization tendency. Conclusions. Spray freeze drying, as opposed to spray drying, produced protein particles with light and porous characteristics, which offered powders with superior aerosol performance due to favorable aerodynamic properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018828425184
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  • 4
    Electronic Resource
    Electronic Resource
    The Effect of Formulation Excipients on Protein Stability and Aerosol Performance of Spray-Dried Powders of a Recombinant Humanized Anti-IgE Monoclonal Antibody1 (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 350-358 
    Details
    ISSN: 1573-904X
    Keywords: aggregation ; glycation ; fine particle fraction ; protein formulation ; protein stability ; spray drying
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To study the effect of trehalose, lactose, and mannitol on the biochemical stability and aerosol performance of spray-dried powders of an anti-IgE humanized monoclonal antibody. Methods. Protein aggregation of spray-dried powders stored at various temperature and relative humidity conditions was assayed by size exclusion chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis. Protein glycation was determined by isoelectric focusing and affinity chromatography. Crystallization was examined by X-ray powder diffraction. Aerosol performance was assessed as the fine particle fraction (FPF) of the powders blended with coarse carrier lactose, and was determined using a multiple stage liquid impinger. Results. Soluble protein aggregation consisting of non-covalent and disulfide-linked covalent dimers and trimers occurred during storage. Aggregate was minimized by formulation with trehalose at or above a molar ratio in the range of 300:1 to 500:1 (excipient:protein). However, the powders were excessively cohesive and unsuitable for aerosol administration. Lactose had a similar stabilizing effect, and the powders exhibited acceptable aerosol performance, but protein glycation was observed during storage. The addition of mannitol also reduced aggregation, while maintaining the FPF, but only up to a molar ratio of 200:1. Further increased mannitol resulted in crystallization, which had a detrimental effect on protein stability and aerosol performance. Conclusions. Protein stability was improved by formulation with carbohydrate. However, a balance must be achieved between the addition of enough stabilizer to improve protein biochemical stability without compromising blended powder aerosol performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018805232453
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  • 5
    Electronic Resource
    Electronic Resource
    Feasibility Study on Spray-Drying Protein Pharmaceuticals: Recombinant Human Growth Hormone and Tissue-Type Plasminogen Activator (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 12-20 
    Details
    ISSN: 1573-904X
    Keywords: spray-drying ; recombinant methionyl human growth hormone ; tissue-type plasminogen activator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018929224005
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of Spray Drying and Subsequent Processing Conditions on Residual Moisture Content and Physical/Biochemical Stability of Protein Inhalation Powders (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 768-775 
    Details
    ISSN: 1573-904X
    Keywords: spray drying ; residual moisture ; equilibrium moisture content ; relative humidity ; gravimetric moisture sorption isotherm ; protein aggregation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011983322594
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  • 7
    Electronic Resource
    Electronic Resource
    Feasibility of protein spray coating using a fluid-bed Würster processor (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 53 (1997), S. 560-566 
    Details
    ISSN: 0006-3592
    Keywords: aggregation ; Ca2+ ; fluid-bed ; microcalorimetry ; rhDNase ; spray coating ; Würster process ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article documents a feasibility study on coating fine powders with protein solutions using a Würster spray coater (GPCG-1 from Glatt Air Techniques, Ramsey, NJ). Spray coating was based on a fluid-bed process where fluidized microcarriers were coated inside the Würster column and dried in the fluidization chamber. Recombinant human deoxyribonuclease (rhDNase) was used as the model protein. Lactose powders of two different size ranges, 53-125 and 125-250 μm, were used as the model microcarrier. The amount of protein applied was varied to obtain coatings of varying thickness. The extent of rhDNase loading determined experimentally was found to be consistent with the theoretical value and was also confirmed visually by scanning electron microscopy. The coating showed a strong integrity after being subjected to mechanical force. However, the protein suffered serious aggregation during coating, most likely due to the thermal stress of the process. Aggregation was significantly reduced when rhDNase was formulated with calcium ions, consistent with the observation that Ca2+ thermally stabilized the protein (as determined by scanning microcalorimetry) in aqueous solution. Thus, our study demonstrates that spray coating, particularly when used in conjunction with rational stabilization strategies, is a feasible alternative to other methods of preparing dried pharmaceutical proteins. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 560-566, 1997.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of high shear on proteins (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 51 (1996), S. 458-465 
    Details
    ISSN: 0006-3592
    Keywords: concentric-cylinder shear device ; rotor/stator homogenization ; shear ; shear rate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Shear is present in almost all bioprocesses and high shear is associated with processes involving agitation and emulsification. The purpose of this study is to investigate the effect of high shear and high shear rate on proteins. Two concentric cylinder-based shear systems were used. One was a closed concentric-cylinder shear device (CCSD) and the other was a homogenizer with a rotor/stator assembly. Mathematical modeling of these systems allowed calculation of the shear rate and shear. The CCSD generated low shear rates (a few hundred s-1), whereas the homogenizer could generate very high shear rates (〉 105 s-1). High shear could be achieved in both systems by increasing the processing time. Recombinant human growth hormone (rhGH) and recombinant human deoxyribonuclease (rhDNase) were used as the model proteins in this study. It was found that neither high shear nor high shear rate had a significant effect on protein aggregation. However, a lower melting temperature and enthalpy were detected for highly sheared rhGH by using scanning microcalorimetry, presumably due to some changes in protein's conformation. Also, SDS-PAGE indicated the presence of low molecular-weight fragments, suggesting that peptide bond breakage occurred due to high shear. rhDNase was relatively more stable than rhGH under high shear. No conformational changes and protein fragments were observed. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Industrial scale harvest of proteins from mammalian cell culture by tangential flow filtration (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 413-422 
    Details
    ISSN: 0006-3592
    Keywords: tangential flow filtration ; pharmaceutical proteins ; plasminogen activator ; linear scale-up ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An industrial-scale methods for harvest of biologically active proteins form mammalian cell culture has been developed using tangential flow filtration. A robust and economical process capable of processing approximately 5000 L conditioned media/h with protein yields in excess of 99% has been achieved. A completely contained system has been designed in which total cell number and viability are maintained throughout the process. The process has successfully been implemented at 1.25 × 104 L scale for the recovery of kilogram quantities of pharmaceutical proteins such as recombinant tissue type plasminogen activator (rt-PA).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380411
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  • 10
    Electronic Resource
    Electronic Resource
    Surface Denaturation at Solid-Void Interface—A Possible Pathway by Which Opalescent Participates Form During the Storage of Lyophilized Tissue-Type Plasminogen Activator at High Temperatures (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 69-77 
    Details
    ISSN: 1573-904X
    Keywords: recombinant tissue-type plasminogen activator (t-PA) ; freezing ; lyophilization ; cake surface area ; opalescent particulates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract During protein lyophilization, it is common practice to complete the freezing step as fast as possible in order to avoid protein denaturation, as well as to obtain a final product of uniform quality. We report a contradictory observation made during lyophilization of recombinant tissue-type plasminogen activator (t-PA) formulated in arginine. Fast cooling during lyophilization resulted in a lyophilized product that yielded more opalescent particulates upon long term storage at 50 °C, under a 150 mTorr nitrogen seal gas environment. Fast cooling also resulted in a lyophilized cake with a large internal surface area. Studies on lyophilized products containing 1% (w/w) residual moisture and varying cake surface areas (0.22 - 1.78 m2/gm) revealed that all lyophilized cakes were in an amorphous state with similar glass transition temperatures (103 - 105 °C). However, during storage the rate of opalescent particulate formation in the lyophilized product (as determined by UV optical density measurement in the 360 to 340 nm range for the reconstituted solution) was proportional to the cake surface area. We suggest that this is a surface-related phenomenon in which the protein at the solid-void interface of the lyophilized cake denatures during storage at elevated temperatures. Irreversible denaturation at the ice-liquid interface during freezing in lyophilization is unlikely to occur, since repeated freezing/thawing did not show any adverse effect on the protein. Infrared spectroscopic analysis could not determine whether protein, upon lyophilization, at the solid-void interface would still be in a native form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016270103863
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