Oligonucleotide Formulations Prepared by High-Speed Electrospinning: Maximizing Loading and Exploring Downstream Processability.

The aim of this study was to develop antisense oligonucleotide tablet formulations using high-speed electrospinning. Hydroxypropyl-beta-cyclodextrin (HPßCD) was used as a stabilizer and as an electrospinning matrix. In order to optimize the morphology of the fibers, electrospinning of various formulations was carried out using water, methanol/water (1:1), and methanol as solvents. The results showed that using methanol could be advantageous due to the lower viscosity threshold for fiber formation enabling higher potential drug loadings by using less excipient. To increase the productivity of electrospinning, high-speed electrospinning technology was utilized and HPßCD fibers containing 9.1% antisense oligonucleotide were prepared at a rate of ~330 g/h. Furthermore, to increase the drug content of the fibers, a formulation with a 50% drug loading was developed. The fibers had excellent grindability but poor flowability. The ground fibrous powder was mixed with excipients to improve its flowability, which enabled the automatic tableting of the mixture by direct compression. The fibrous HPßCD-antisense oligonucleotide formulations showed no sign of physical or chemical degradation over the 1-year stability study, which also shows the suitability of the HPßCD matrix for the formulation of biopharmaceuticals. The obtained results demonstrate possible solutions for the challenges of electrospinning such as scale-up and downstream processing of the fibers.

Powder filling of electrospun material in vials: A proof-of-concept study.

The present paper reports the powder filling of milled electrospun materials in vials, which contained voriconazole and sulfobutylether-ß-cyclodextrin. High-speed electrospinning was used for the production of the fibrous sample, which was divided into 6 parts. Each portion was milled using different milling methods and sizes of sieves to investigate whether the milling influences the powder and filling properties. Bulk and tapped density tests, laser diffraction and angle of repose measurements were applied to characterize the milled powders, while a vibratory feeder was used for the feeding experiments. The correlation between the material property descriptors and the feeding responses was investigated by multivariate data analysis. Based on the results, three samples were chosen for the vial filling, which was accomplished with 3400 mg electrospun material containing 200 mg voriconazole, representative of the commercial product. The feed rate was set to fit the 240 g/h production rate of the electrospinning and the relative standard deviation of three repeated vial filling was determined to see the accuracy of the process. This research shows that by applying a suitable milling method it is possible to process electrospun fibers to a powder, which can be filled into vials and used as reconstitution dosage forms.

Continuous downstream processing of milled electrospun fibers to tablets monitored by near-infrared and Raman spectroscopy.

Electrospinning is a technology for manufacture of nano- and micro-sized fibers, which can enhance the dissolution properties of poorly water-soluble drugs. Tableting of electrospun fibers have been demonstrated in several studies, however, continuous manufacturing of tablets have not been realized yet. This research presents the first integrated continuous processing of milled drug-loaded electrospun materials to tablet form supplemented by process analytical tools for monitoring the active pharmaceutical ingredient (API) content. Electrospun fibers of an amorphous solid dispersion (ASD) of itraconazole and poly(vinylpyrrolidone-co-vinyl acetate) were produced using high speed electrospinning and afterwards milled. The milled fibers with an average fiber diameter of 1.6 ± 0.9 µm were continuously fed with a vibratory feeder into a twin-screw blender, which was integrated with a tableting machine to prepare tablets with ~ 10 kN compression force. The blend of fibers and excipients leaving the continuous blender was characterized with a bulk density of 0.43 g/cm3 and proved to be suitable for direct tablet compression. The ASD content, and thus the API content was determined in-line before tableting and at-line after tableting using near-infrared and Raman spectroscopy. The prepared tablets fulfilled the USP <905> content uniformity requirement based on the API content of ten randomly selected tablets. This work highlights that combining the advantages of electrospinning (e.g. less solvent, fast and gentle drying, low energy consumption, and amorphous products with high specific surface area) and the continuous technologies opens a new and effective way in the field of manufacturing of the poorly water-soluble APIs.

Monoclonal antibody formulation manufactured by high-speed electrospinning.

Solid formulations of monoclonal antibodies present several advantages, such as improved stability and increased shelf-life as well as simpler storage and transportation. In this study, we present a gentle drying technology for monoclonal antibodies, applying the water soluble 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD) as matrix, to prepare a solid reconstitution dosage form. High-speed electrospinning of an aqueous infliximab-containing HP-ß-CD solution was carried out at 25 °C resulting in fibers with an average diameter of 2.5 µm. The mAb-loaded electrospun fibers were successful to preserve the stability of infliximab in solid form. The results of size exclusion chromatography and gel electrophoresis indicated no significant increase in aggregate formation during the electrospinning process compared to the initial matrix solution. The binding activity of infliximab was preserved during electrospinning compared to the reference liquid formulation. Due to the enhanced surface area, excellent reconstitution capability, i.e. clear solution within 2 min without any vigorous mixing, could be achieved in a small-scale reconstitution test. The results of this work demonstrate that high-speed electrospinning is a very promising technique to manufacture the solid formulation of monoclonal antibodies for applications such as fast reconstitutable powders.

Electrospun Solid Formulation of Anaerobic Gut Microbiome Bacteria.

A model anaerobic bacterium strain from the gut microbiome (Clostridium butyricum) producing anti-inflammatory molecules was incorporated into polymer-free fibers of a water-soluble cyclodextrin matrix (HP-ß-CD) using a promising scaled-up nanotechnology, high-speed electrospinning. A long-term stability study was also carried out on the bacteria in the fibers. Effect of storage conditions (temperature, presence of oxygen) and growth conditions on the bacterial viability in the fibers was investigated. The viability of the sporulated anaerobic bacteria in the fibers was maintained during 12 months of room temperature storage in the presence of oxygen. Direct compression was used to prepare tablets from the produced bacteria-containing fibers after milling (using an oscillating mill) and mixing with tableting excipients, making easy oral administration of the bacteria possible. No significant decrease was observed in bacterial viability following the processing of the fibers (milling and tableting).

Scale-up of electrospinning technology: Applications in the pharmaceutical industry.

Recently, electrospinning (ES) of fibers has been shown to be an attractive strategy for drug delivery. One of the main features of ES is that a wide variety of drugs can be loaded into the fibers to improve their bioavailability, to enhance dissolution, or to achieve controlled release. Besides, ES is a continuous technology with low energy consumption, which can make it a very economic production alternative to the widely used freeze drying and spray drying. However, the low production rate of laboratory-scaled ES has limited the industrial application of the technology so far. This article covers the various ES technologies developed for scaled-up fiber production with an emphasis on pharmaceutically relevant examples. The methods used for increasing the productivity are complied, which is followed by a review of specific examples from literature where these technologies are utilized to produce oral drug delivery systems. The different technologies are compared in terms of their basic principles, advantages, and limitations. Finally, the different downstream processing options to prepare tablets or capsules containing the electrospun drug are covered as well. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Continuous drying of a protein-type drug using scaled-up fiber formation with HP-ß-CD matrix resulting in a directly compressible powder for tableting.

The goals of this work were to evaluate if high-speed electrospinning can be used as a gentle and continuous drying technology to produce protein-containing cyclodextrin-based fibers from an aqueous solution and to convert the produced protein-cyclodextrin fibers into a directly compressible powder. A 400 mL/h feeding rate was used during the electrospinning experiments, corresponding to a ~270 g/h production rate of the dried material. The produced fibers were collected in a cyclone. The fibers were found grindable without secondary drying, and the ground powder was mixed with tableting excipients and was successfully tableted by direct compression. The model protein-type drug (ß-galactosidase) remained stable during each of the processing steps (electrospinning, grinding, tableting) and after 6 months of storage at room temperature in the tablets. The obtained results demonstrate that high speed electrospinning can be a gentle alternative to traditional drying methods used for protein-type drugs, and that tablet formulation is achievable from the electrospun material prepared this way.

Scaled-Up Production and Tableting of Grindable Electrospun Fibers Containing a Protein-Type Drug.

The aims of this work were to develop a processable, electrospun formulation of a model biopharmaceutical drug, ß-galactosidase, and to demonstrate that higher production rates of biopharmaceutical-containing fibers can be achieved by using high-speed electrospinning compared to traditional electrospinning techniques. An aqueous solution of 7.6 w/w% polyvinyl alcohol, 0.6 w/w% polyethylene oxide, 9.9 w/w% mannitol, and 5.4 w/w% ß-galactosidase was successfully electrospun with a 30 mL/h feeding rate, which is about 30 times higher than the feeding rate usually attained with single-needle electrospinning. According to X-ray diffraction measurements, polyvinyl alcohol, polyethylene oxide, and ß-galactosidase were in an amorphous state in the fibers, whereas mannitol was crystalline (δ-polymorph). The presence of crystalline mannitol and the low water content enabled appropriate grinding of the fibrous sample without secondary drying. The ground powder was mixed with excipients commonly used during the preparation of pharmaceutical tablets and was successfully compressed into tablets. ß-galactosidase remained stable during each of the processing steps (electrospinning, grinding, and tableting) and after one year of storage at room temperature in the tablets. The obtained results demonstrate that high-speed electrospinning is a viable alternative to traditional biopharmaceutical drying methods, especially for heat sensitive molecules, and tablet formulation is achievable from the electrospun material prepared this way.

Continuous alternative to freeze drying: Manufacturing of cyclodextrin-based reconstitution powder from aqueous solution using scaled-up electrospinning.

The aims of this study were to evaluate electrospinning as a continuous alternative to freeze drying in the production of a reconstitution injection dosage form, and to prove that aqueous electrospinning can be realized with a high production rate at room temperature. High-speed electrospinning with a novel continuous cyclone collection was used to manufacture a formulation of the poorly water-soluble antifungal voriconazole (VOR) with sulfobutylether-ß-cyclodextrin (SBE-ß-CD). The freeze-dried, marketed product of this drug substance, Vfend® also contains SBE-ß-CD as excipient. SBE-ß-CD acted as a 'quasi-polymer', and it could be electrospun despite its low molecular mass (2163 Da). According to X-ray diffraction and differential scanning calorimetry, no traces of crystalline VOR were detectable in the fibers. Furthermore, Raman mapping and energy dispersive spectroscopy measurements showed a uniform distribution of amorphous VOR in the fibers. Reconstitution tests carried out with ground fibrous powder showed complete dissolution resulting in a clear solution after 30 s (similarly to Vfend®). The high productivity rate (~240 g/h) achieved using high-speed electrospinning makes this scaled-up, continuous and flexible manufacturing process capable of fulfilling the technological and capacity requirements of the pharmaceutical industry. This work shows that aqueous high-speed electrospinning, being a continuous and high-throughput process, is an economically viable production alternative to freeze drying.

Drying technology strategies for colon-targeted oral delivery of biopharmaceuticals.

In chronic intestinal diseases like inflammatory bowel disease, parenteral administration of biopharmaceuticals is associated with numerous disadvantages including immune reactions, infections, low patient compliance, and toxicity caused by high systemic bioavailability. One alternative that can potentially overcome these limitations is oral administration of biopharmaceuticals, where the local delivery will reduce the systemic exposure and furthermore the manufacturing costs will be lower. However, the development of oral dosage forms that deliver the biologically active form to the intestines is one of the greatest challenges for pharmaceutical technologists due to the sensitive nature of biopharmaceuticals. The present article discusses the various drug delivery technologies used to produce orally administered solid dosage forms of biopharmaceuticals with an emphasis on colon-targeted delivery. Solid oral dosage compositions containing different types of colon-targeting biopharmaceuticals are compiled followed by a review of currently applied and emerging drying technologies for biopharmaceuticals. The different drying technologies are compared in terms of their advantages, limitations, costs and their effect on product stability.

Oral bioavailability enhancement of flubendazole by developing nanofibrous solid dosage forms.

The bioavailability of the anthelminthic flubendazole was remarkably enhanced in comparison with the pure crystalline drug by developing completely amorphous electrospun nanofibres with a matrix consisting of hydroxypropyl-ß-cyclodextrin and polyvinylpyrrolidone. The thus produced formulations can potentially be active against macrofilariae parasites causing tropical diseases, for example, river blindness and elephantiasis, which affect altogether more than a hundred million people worldwide. The bioavailability enhancement was based on the considerably improved dissolution. The release of a dose of 40 mg could be achieved within 15 min. Accordingly, administration of the nanofibrous system ensured an increased plasma concentration profile in rats in contrast to the practically non-absorbable crystalline flubendazole. Furthermore, easy-to-grind fibers could be developed, which enabled compression of easily administrable immediate release tablets.

Lubricant-Induced Crystallization of Itraconazole From Tablets Made of Electrospun Amorphous Solid Dispersion.

Investigation of downstream processing of nanofibrous amorphous solid dispersions to generate tablet formulation is in a quite early phase. Development of high speed electrospinning opened up the possibility to study tableting of electrospun solid dispersions (containing polyvinylpyrrolidone-vinyl acetate and itraconazole [ITR] in this case). This work was conducted to investigate the influence of excipients on dissolution properties and the feasibility of scaled-up rotary press tableting. The dissolution rates from tablets proved to be mainly composition dependent. Magnesium stearate acted as a nucleation promoting agent (providing an active hydrophobic environment for crystallization of ITR) hindering the total dissolution of ITR. This crystallization process proved to be temperature dependent as well. However, the extent of dissolution of more than 95% was realizable when a less hydrophobic lubricant, sodium stearyl fumarate (soluble in the medium), was applied. Magnesium stearate induced crystallization even if it was put in the dissolution medium next to proper tablets. After optimization of the composition, scaled-up tableting on a rotary press was carried out. Appropriate dissolution of ITR from tablets was maintained for 3 months at 25°C/60% relative humidity. HPLC measurements confirmed that ITR was chemically stable both in the course of downstream processing and storage.

Evaluation of Three Amorphous Drug Delivery Technologies to Improve the Oral Absorption of Flubendazole.

This study investigates 3 amorphous technologies to improve the dissolution rate and oral bioavailability of flubendazole (FLU). The selected approaches are (1) a standard spray-dried dispersion with hydroxypropylmethylcellulose (HPMC) E5 or polyvinylpyrrolidone-vinyl acetate 64, both with Vitamin E d-α-tocopheryl polyethylene glycol succinate; (2) a modified process spray-dried dispersion (MPSDD) with either HPMC E3 or hydroxypropylmethylcellulose acetate succinate (HPMCAS-M); and (3) confining FLU in ordered mesoporous silica (OMS). The physicochemical stability and in vitro release of optimized formulations were evaluated following 2 weeks of open conditions at 25°C/60% relative humidity (RH) and 40°C/75% RH. All formulations remained amorphous at 25°C/60% RH. Only the MPSDD formulation containing HPMCAS-M and 3/7 (wt./wt.) FLU/OMS did not crystallize following 40°C/75% RH exposure. The OMS and MPSDD formulations contained the lowest and highest amount of hydrolyzed degradant, respectively. All formulations were dosed to rats at 20 mg/kg in suspension. One FLU/OMS formulation was also dosed as a capsule blend. Plasma concentration profiles were determined following a single dose. In vivo findings show that the OMS capsule and suspension resulted in the overall highest area under the curve and Cmax values, respectively. These results cross-evaluate various amorphous formulations and provide a link to enhanced biopharmaceutical performance.

AC and DC electrospinning of hydroxypropylmethylcellulose with polyethylene oxides as secondary polymer for improved drug dissolution.

Alternating current electrospinning (ACES) capable to reach multiple times higher specific productivities than widely used direct current electrospinning (DCES) was investigated and compared with DCES to prepare drug-loaded formulations based on one of the most widespread polymeric matrix used for commercialized pharmaceutical solid dispersions, hydroxypropylmethylcellulose 2910 (HPMC). In order to improve the insufficient spinnability of HPMC (both with ACES and DCES) polyethylene oxide (PEO) as secondary polymer with intense ACES activity was introduced into the electrospinning solution. Different grades of this polymer used at as low concentrations in the fibers as 0.1% or less enabled the production of high quality HPMC-based fibrous mats without altering its physicochemical properties remarkably. Increasing concentrations of higher molecular weight PEOs led to the thickening of fibers from submicronic diameters to several microns of thickness. ACES fibers loaded with the poorly water-soluble model drug spironolactone were several times thinner than drug-loaded fibers prepared with DCES in spite of the higher feeding rates applied. The amorphous HPMC-based fibers with large surface area enhanced the dissolution of spironolactone significantly, the presence of small amounts of PEO did not affect the dissolution rate. The presented results confirm the diverse applicability of ACES, a novel technique to prepare fibrous drug delivery systems.

Alternating current electrospinning for preparation of fibrous drug delivery systems.

Alternating current electrospinning (ACES) was compared to direct current electrospinning (DCES) for the preparation of drug-loaded nanofibrous mats. It is generally considered that DCES is the solely technique to produce nanofibers using the electrostatic force from polymer solutions, however, less studied and also capable ACES provides further advantages such as increased specific productivities. A poorly water-soluble drug (carvedilol) was incorporated into the fibers based on three different polymeric matrices (an acid-soluble terpolymer (Eudragit(®) E), a base-soluble copolymer (Eudragit(®) L 100-55) and a nonionic homopolymer (polyvinylpyrrolidone K90)) to improve the dissolution of the weak base drug under different pH conditions. Morphology and fiber diameter evaluation showed similar electrospun fibers regardless the type of the high voltage and the major differences in feeding rates. The amorphous ACES and DCES fibers provided fast and total drug dissolutions in all cases. The presented results show that ACES can be a more feasible novel alternative to formulate fibers for drug delivery purposes.

Comparison of spray drying, electroblowing and electrospinning for preparation of Eudragit E and itraconazole solid dispersions.

Three solvent based methods: spray drying (SD), electrospinning (ES) and air-assisted electrospinning (electroblowing; EB) were used to prepare solid dispersions of itraconazole and Eudragit E. Samples with the same API/polymer ratios were prepared in order to make the three technologies comparable. The structure and morphology of solid dispersions were identified by scanning electron microscopy and solid phase analytical methods such as, X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and Raman chemical mapping. Moreover, the residual organic solvents of the solid products were determined by static headspace-gas chromatography/mass spectroscopy measurements and the wettability of samples was characterized by contact angle measurement. The pharmaceutical performance of the three dispersion type, evaluated by dissolution tests, proved to be very similar. According to XRPD and DSC analyses, made after the production, all the solid dispersions were free of any API crystal clusters but about 10 wt% drug crystallinity was observed after three months of storage in the case of the SD samples in contrast to the samples produced by ES and EB in which the polymer matrix preserved the API in amorphous state.

Melt-blown and electrospun drug-loaded polymer fiber mats for dissolution enhancement: a comparative study.

Melt blowing (MB) was investigated to prepare a fast dissolving fibrous drug-loaded solid dispersion and compared with solvent-based electrospinning (SES) and melt electrospinning (MES). As a conventional solvent-free technique coupled with melt extrusion and using a high-speed gas stream, MB can provide high-quality micro- and nanofibers at industrial throughput levels. Carvedilol, a weak-base model drug with poor water solubility, was processed using a common composition optimized for the fiber spinning and blowing methods based on a hydrophilic vinylpyrrolidone-vinyl acetate copolymer (PVPVA64) and PEG 3000 plasticizer. Scanning electron microscopy combined with fiber diameter analysis showed diameter distributions characteristic to each prepared fibrous fabrics (the mean value increased toward SES

High speed electrospinning for scaled-up production of amorphous solid dispersion of itraconazole.

High speed electrospinning (HSES), compatible with pharmaceutical industry, was used to demonstrate the viability of the preparation of drug-loaded polymer nanofibers with radically higher productivity than the known single-needle electrospinning (SNES) setup. Poorly water-soluble itraconazole (ITRA) was formulated with PVPVA64 matrix polymer using four different solvent-based methods such as HSES, SNES, spray drying (SD) and film casting (FC). The formulations were assessed in terms of improvement in the dissolution rate of ITRA (using a "tapped basket" dissolution configuration) and analysed by SEM, DSC and XRPD. Despite the significantly increased productivity of HSES, the obtained morphology was very similar to the SNES nanofibrous material. ITRA transformed into an amorphous form, according to the DSC and XRPD results, in most cases except the FC samples. The limited dissolution of crystalline ITRA could be highly improved: fast dissolution occurred (>90% within 10min) in the cases of both (the scaled-up and the single-needle) types of electrospun fibers, while the improvement in the dissolution rate of the spray-dried microspheres was significantly lower. Production of amorphous solid dispersions (ASDs) with the HSES system proved to be flexibly scalable and easy to integrate into a continuous pharmaceutical manufacturing line, which opens new routes for the development of industrially relevant nanopharmaceuticals.

Application of PAMPA-models to predict BBB permeability including efflux ratio, plasma protein binding and physicochemical parameters.

This study examines whether algorithms to predict brain penetration of 88 drug candidates could benefit from inclusion of PAMPA data such as P(eff), flux and membrane retention. Specifically the ability to fit experimentally derived LogBB data with PAMPA information and compound related physicochemical and structural parameters was assessed. Collected data were analyzed by partial least square analysis and various regression models for LogBB. Four PAMPA methodologies were evaluated in this study including: (1) a PAMPA-BLM (black lipid membrane) model, (2) a PAMPA-DS (double sink) model, (3) a PAMPA-BBB (blood-brain barrier) model and (4) a PAMPA-BBB-UWL (unstirred water layer). Additionally, plasma protein binding (PPB) experiments and a Caco-2 assay were performed to determine the unbound fraction in plasma and the efflux ratio, respectively, for subsets of the selected compounds. This information was combined with the obtained PAMPA data in an effort to improve the predictions of LogBB. Taken in aggregate, the results presented, suggest that the PAMPA-BLM parameters are the most important contributors to predict the LogBB. The optimized multiple linear regression (MLR) relationship including the PAMPA-BLM properties demonstrated a slightly improved prediction compared to the model without the PAMPA-BLM parameters. Including the plasma protein binding of 15 compounds resulted in a significantly improved PAMPA-BLM prediction of LogBB, while integrating the efflux ratio with PAMPA-BLM or PAMPA-BBB P(eff) values, resulted in improved classification of brain permeable [BBB+(LogBB>/=0)] and impermeable [BBB-(LogBB<0)] compounds.