Aqueous two-phase systems as a formulation concept for spray-dried protein

Exploring vacuum foam drying as an alternative to freeze-drying and spray drying for a human lipase

This article compares and explores vacuum foam-drying as an alternative drying technology to freeze-drying and spray drying for a recombinant human lipase as the model protein. Materials characteristics such as structure, surface composition and the solid-state properties of the dry materials were compared and investigated. Moreover, the technical functionality in terms of reconstitution characteristics and the lipase stability were also investigated. The stability of the lipase was evaluated through activity measurements. Sucrose and dextran D40 (40 kDa) were used as matrix former and the surfactant α-dodecyl maltoside was used as surface active additive. The study demonstrated that the drying technique greatly influenced the material structure and composition which in turn affected the reconstitution characteristics. The lipase was overrepresented at the material surface in declining order spray-dried > vacuum foam-dried > freeze-dried. The lipase activity was retained up to 10 % lipase content in solids, but at 20 % lipase a loss of activity was observed for all drying techniques. Phase separation in the solid material may be an explanation. Vacuum foam-drying shows promise as an alternative drying technique for the lipase, and potentially other proteins.

On the role of excipients in biopharmaceuticals manufacture: Modelling-guided formulation identifies the protective effect of arginine hydrochloride excipient on spray-dried Olipudase alfa recombinant protein

Biopharmaceuticals are labile biomolecules that must be safeguarded to ensure the safety, quality, and efficacy of the product. Batch freeze-drying is an established means of manufacturing solid biopharmaceuticals but alternative technologies such as spray-drying may be more suitable for continuous manufacturing of inhalable biopharmaceuticals. Here we assessed the feasibility of spray-drying Olipudase alfa, a novel parenteral therapeutic enzyme, by evaluating some of its critical quality attributes (CQAs) in a range of excipients, namely, trehalose, arginine (Arg), and arginine hydrochloride (Arg-HCl) in the sucrose/methionine base formulation. The Arg-HCl excipient produced the best gain in CQAs of spray-dried Olipudase with a 63% reduction in reconstitution time and 83% reduction in the optical density of the solution. Molecular dynamics simulations revealed the atomic-scale mechanism of the protein-excipient interactions, substantiating the experimental results. The Arg-HCl effect was explained by the calculated thermal stability and structural order of the protein wherein Arg-HCl acted as a crowding agent to suppress protein aggregation and promote stabilization of Olipudase post-spray-drying. Therefore, by rational selection of appropriate excipients, our experimental and modelling dataset confirms spray-drying is a promising technology for the manufacture of Olipudase and demonstrates the potential to accelerate development of continuous manufacturing of parenteral biopharmaceuticals.

Enhanced delivery efficiency and sustained release of biopharmaceuticals by complexation-based gel encapsulated coated microneedles: rhIFNα-1b example

Coated microneedles (MNs) are widely used for delivering biopharmaceuticals. In this study, a novel gel encapsulated coated MNs (GEC-MNs) was developed. The water-soluble drug coating was encapsulated with sodium alginate (SA) in situ complexation gel. The manufacturing process of GEC-MNs was optimized for mass production. Compared to the water-soluble coated MNs (72.02% ± 11.49%), the drug delivery efficiency of the optimized GEC-MNs (88.42% ± 6.72%) was steadily increased, and this improvement was investigated through in vitro drug release. The sustained-release of BSA was observed in vitro permeation through the skin. The rhIFNα-1b GEC-MNs was confirmed to achieve biosafety and 6-month storage stability. Pharmacokinetics of rhIFNα-1b in GEC-MNs showed a linearly dose-dependent relationship. The AUC of rhIFNα-1b in GEC-MNs (4.51 ng/ml·h) was bioequivalent to the intradermal (ID) injection (5.36 ng/ml·h) and significantly higher than water-soluble coated MNs (3.12 ng/ml·h). The rhIFNα-1b elimination half-life of GEC-MNs, soluble coated MNs, and ID injection was 18.16, 1.44, and 2.53 h, respectively. The complexation-based GEC-MNs have proved to be more efficient, stable, and achieve the sustained-release of water-soluble drug in coating MNs, constituting a high value to biopharmaceutical.

Preparation of polysaccharide glassy microparticles with stabilization of proteins

This study investigates a method of preparing hazard-resistant protein-loaded polysaccharide glassy microparticles using freezing-induced phase separation method without exposure to water/oil, water/air interface and cross-linking reagents. Model protein (such as bovine serum albumin, myoglobin and beta-galactosidase (beta-Gal)) was dissolved in water together with dextran and polyethylene glycol (PEG), followed by a freezing process to form a temperature-stabilized aqueous-aqueous emulsion wherein dextran separated out as the dispersed phase with protein partitioned in preferentially. The frozen sample was freeze-dried and washed with dichloromethane (DCM) to remove the PEG continuous phase, after which protein-loaded polysaccharide particles, 1-4 microm in diameter, were harvested. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) patterns showed that the particles were in glassy state. These glassy polysaccharide microparticles can well protect the delicate structure of proteins and preserve their bioactivities under deleterious environment interacting with organic solvents, vortex and centrifugation processes that often involve during the formulation processes leading to polymer-based sustained-release systems. Therefore, this freezing-induced phase separation method is a mild and effective way to encapsulate protein into hazard-resistant polysaccharide glassy particles, which ensure its stability in subsequent formulating processes that leads to polymer-based sustained-release system.

Pharmaceutical particle engineering via spray drying

This review covers recent developments in the area of particle engineering via spray drying. The last decade has seen a shift from empirical formulation efforts to an engineering approach based on a better understanding of particle formation in the spray drying process. Microparticles with nanoscale substructures can now be designed and their functionality has contributed significantly to stability and efficacy of the particulate dosage form. The review provides concepts and a theoretical framework for particle design calculations. It reviews experimental research into parameters that influence particle formation. A classification based on dimensionless numbers is presented that can be used to estimate how excipient properties in combination with process parameters influence the morphology of the engineered particles. A wide range of pharmaceutical application examples—low density particles, composite particles, microencapsulation, and glass stabilization—is discussed, with specific emphasis on the underlying particle formation mechanisms and design concepts.

An atomic force microscopy approach for assessment of particle density applied to single spray-dried carbohydrate particles

To evaluate an atomic force microscopy (AFM) approach for effective density analysis of single spray dried carbohydrate particles in order to investigate the internal structure of the particles. In addition, the AFM method was compared to an established technique, that is gas pycnometry. Resonant frequency AFM analysis was employed for determination of the mass of individual particles of spray-dried lactose, mannitol, and a mixture of sucrose/dextran (4:1). The effective particle density was calculated using the diameter of the spherical particles obtained from light microscopy. The apparent particle density was further analyzed with gas pycnometry. It was observed by microscopy that particles appeared either "solid" or "hollow." A solid appearance applied to an effective particle density close to the true density of the material, whereas a density around 1 g/cm(3) corresponded to a hollow appearance. However, carbohydrates, which crystallized during spray drying, for example, mannitol appeared solid but the average effective particle density was 0.95 g/cm(3), indicating a continuous but porous structure. AFM measurements of effective particle density corroborate the suggestion of differences in particle structure caused by the varying propensity of carbohydrates to crystallize during spray drying, resulting in mainly either amorphous hollow or crystalline porous particles.

Design of fine particles for pulmonary drug delivery

Particle design for inhalation is characterized by advances in particle processing methods and the utilization of new excipients. Processing methods such as spray drying allow control over critical particle design features, such as particle size and distribution, surface energy, surface rugosity, particle density, surface area, porosity and microviscosity. Control of these features has enabled new classes of therapeutics to be delivered by inhalation. These include therapeutics that have a narrow therapeutic index, require a high delivered dose, and/or elicit their action systemically. Engineered particles are also being utilized for immune modulation, with exciting advances being made in the delivery of antibodies and inhaled vaccines. Continued advances are expected to result in 'smart' therapeutics capable of active targeting and intracellular trafficking.

Particle engineering techniques for inhaled biopharmaceuticals

Formulation of biopharmaceuticals for pulmonary delivery is faced with the challenge of producing particles with the optimal properties for deep lung deposition without altering the native conformation of these molecules. Traditional techniques such as milling are continuously being improved while newer and more advanced techniques such as spray drying, spray freeze drying and supercritical fluid technology are being developed so as to optimize pulmonary delivery of biopharmaceuticals. While some of these techniques are quite promising, some are harsh and impracticable. Method scale up, cost-effectiveness and safety issues are important factors to be considered in the choice of a technique. This paper reviews the presently developed techniques for particle engineering biopharmaceuticals.

The influence of PVP incorporation on moisture-induced surface crystallization of amorphous spray-dried lactose particles

We have recently shown that atomic force microscopy (AFM) may be an appropriate method for characterisation of the re-crystallization of amorphous particles. In this study, spray-dried composite particles consisting of lactose and polyvinyl pyrrolidon (PVP) were characterised by AFM and electron spectroscopy for chemical analysis (ESCA), and their response on increasing the relative humidity (RH) was investigated. The PVP content in the particles used was 0, 5 or 25 wt.% of either PVP K17 or PVP K90. All composite particles were found to be enriched with PVP at the surface. The incorporation of PVP in the particles influenced the way the particles responded to an increase in RH. The specific RH interval in which the surface of the particles smoothened and the RH where crystallization could be detected, increased with an increase in the amount and molecular weight of the PVP in the particles. The crystallization kinetics of single particles was analysed with AFM and by utilising the JMAK equation. The rate constant for this transformation increased in an exponential manner with increasing RH. Furthermore, above the RH needed for the crystallization to occur, the exponential increase in the crystallization rate was larger for particles with higher polymer content which indicates that the stabilising effect decreases as the water content in the particles becomes higher. In this study we report a method for determination of crystallization kinetics on single composite particles, which is valuable when evaluating the effect of stabilisers in amorphous powders.

In situ coating--an approach for particle modification and encapsulation of proteins during spray-drying

In this paper, we present a method for in situ coating of individual protein particles in a respirable size. The aim of the coating was to influence the particle/powder properties, and to reduce or prevent surface-induced conformational changes of the protein, during spray-drying, which was the method used for simultaneously preparing and coating particles. The investigated formulations included bovine serum albumin (BSA), trehalose and either of the two non-ionic polymers, hydroxypropyl methylcellulose (HPMC) and poly(ethylene oxide)-poly(propylene oxide) triblock co-polymer (Poloxamer 188). Complete protein coating as measured by electron spectroscopy for chemical analysis (ESCA) was achieved at a polymer concentration of approximately 1% of the total solids weight, and could be predicted from the dynamic surface tension at the air/water interface, as measured by the pendant drop method. Further, particle properties such as: size, dissolution time, powder flowability, and apparent particle density, as measured by gas pycnometry, were affected by the type and concentration of the polymer. In addition, the particle surface morphology could possibly be correlated to the surface elasticity of the droplet surface during drying. Moreover, an extensive investigation (Fourier transform infrared spectroscopy, circular dichroism and size exclusion chromatography) of the structural effects of protein encapsulated in a polymeric coating suggested that in situ coating provide particulate formulations with preserved native conformation and with a high stability during rehydration.

Particle size and density in spray drying-effects of carbohydrate properties

The purpose of this study was to examine some fundamental aspects of the particle formation during spray drying, related to particle size and density. Particles were prepared in a laboratory spray dryer from carbohydrates with different solubility and crystallization propensity, such as lactose, mannitol, and sucrose/dextran 4:1. The feed concentrations ranged from 1% w/w to saturated and the size of droplets and particles were measured by laser diffraction. Particles were also characterized by various microscopy techniques (i.e., scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and light microscopy), differential scanning calorimetry (DSC), gas adsorption, and gas pycnometry. As demonstrated larger particles could be obtained by either increasing the droplet size during atomization; increasing the concentration of the feed solution; or decreasing the solubility of the solute. The apparent particle density, measured by gas pycnometry, was found negatively correlated to the feed concentration. Due to the nonlinear relationship between the feed concentration and the particle size, it was concluded that higher solids load would cause an increase in the effective particle density and that the reduction in the apparent particle density was a result of a gradually less permeable particle surface. Further, the crystallization propensity of the carbohydrate influenced the particle formation and resulted in either hollow or porous particles.