Influence of process parameters on the preparation of pharmaceutical films by electrostatic powder deposition (original) (raw)
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Electrostatic powder deposition to prepare films for drug delivery
Journal of Drug Delivery Science and Technology, 2015
An electrostatic powder deposition (ESPD) method was developed to prepare free films for drug delivery. Films were prepared using polyethylene oxide (PEO), a physical mixture of PEO and acetaminophen (APAP), and co-processed PEO and APAP particles. Compositions were charged by an electrostatic spray gun and deposited onto a grounded stainless steel coupon. The deposited powders were cured and free films were peeled from the substrate. Average drug content of the active films was 97% of theoretical. Films prepared using the physical mixture of the powders showed greater variability with an RSD of 11.9% compared to 1.8% from films prepared using co-processed particles. Mechanical testing of the prepared films showed lower puncture strength than commercially available Listerine ® strips, but exhibited greater elongation prior to break. Active films showed up to 15% elongation compared to 1.6% from Listerine ® strips and 3.8% from PEO films, due primarily to the plasticizing effect of APAP on PEO in the drug containing films. Both active films exhibited greater than 85% drug release in 2 min. This study is the first to demonstrate the application of ESPD to prepare free films for drug delivery; however, future studies of this technology are needed to determine its full potential.
Influence of powder properties on the performance of electrostatic coating process
Journal of Electrostatics, 1997
Properties of powder, e.g. particle size distribution, chemical composition, triboand corona charging characteristics, electrical resistivity, hygroscopicity, fluidity and shape distribution play significant roles on the performance of powder coating such as transfer efficiency, film thickness, adhesion and appearance. Our focus in this paper is on particle size distribution, fluidity, charging characteristics and their effects on the first pass transfer efficiency. Even a minor difference in powder properties showed differences in the applications process illustrating the importance of characterizing physical parameters and control techniques to achieve desirable performance.
Electrostatic spray deposition (ESD) of polymeric powders on thermoplastic (PA66) substrate
Surface & Coatings Technology, 2006
This paper deals with a primerless electrostatic spray deposition process (ESD) for coating thermoplastic (PA66) substrates using epoxypolyester, metallic epoxy-polyester, and epoxy powder paint. A novel and never before used pretreatment system, based on a low speed cold spray of fine copper powders, applied a thin conductive film on the plastic substrate, which made the ESD possible.
Electrostatic fluidized bed deposition of a high performance polymeric powder on metallic substrates
Surface & Coatings Technology, 2006
The electrostatic fluidized bed deposition of a single-layer PPA 571 coating onto low carbon steel rods is reported. A full factorial experimental design was developed in order to study the influence of several operative variables on the effectiveness of the coating process and on the coating thickness and uniformity. The operative variables included exposure time, air flow, the applied voltage, attitude, and the radial and vertical location of the work-piece in the fluid bed. After the experimentation, several process maps were developed as a support to identify the best way to lead the coating process. Finally, by using a statistical approach, the reliability and repeatability of the coating process was also established.
The Application of Electrostatic Dry Powder Deposition Technology to Coat Drug-Eluting Stents
Pharmaceutical Research, 2010
A novel methodology has been introduced to effectively coat intravascular stents with sirolimus-loaded polymeric microparticles. Methods. Dry powders of the microparticulate formulation, consisting of non-erodible polymers, were produced by a supercritical, aerosol, solvent extraction system (ASES). A design of experiment (DOE) approach was conducted on the independent variables, such as organic/CO 2 phase volume ratio, polymer weight and stirring-rate, while regression analysis was utilized to interpret the influence of all operational parameters on the dependent variable of particle size. The dry powders, so formed, entered an electric field created by corona charging and were sprayed on the earthed metal stent. Furthermore, the thermal stability of sirolimus was investigated to define the optimum conditions for fusion to the metal surfaces. Results. The electrostatic dry powder deposition technology (EDPDT) was used on the metal strut followed by fusion to produce uniform, reproducible and accurate coatings. The coated stents exhibited sustained release profiles over 25 days, similar to commercial products. EDPDT-coated stents displayed significant reduced platelet adhesion. Conclusions. EDPDT appeared to be a robust accurate and reproducible technology to coat eluting stents.
Thin Solid Films, 2005
In order to deposit biomedical calcium phosphate (CaP) coatings with a defined surface morphology, the electrostatic spray deposition (ESD) technique was used since this technique offers the possibility to deposit ceramic coatings with a variety of surface morphologies. A scanning electron microscopical study was performed in order to investigate the influence of several deposition parameters on the final morphology of the deposited coatings. The chemical characteristics of the coatings were studied by means of X-ray diffraction and Fouriertransform infrared spectroscopy.
Journal of Biomedical Materials Research Part A, 2005
The electrostatic spray deposition (ESD) technique offers the possibility of depositing calcium phosphate (CaP) coatings onto various substrate materials with defined chemical and morphological properties. The relationship between physical, apparatus-related deposition parameters, and the chemical characteristics of ESD coatings was investigated by means of X-ray diffraction, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy to be able to deposit CaP coatings with tailored chemical properties. The results showed that the chemical characteristics of CaP coatings, deposited with use of the ESD technique, were strongly dependent on the deposition temperature, the nozzle-to-substrate distance, the liquid flow rate, and the geometry of the spraying nozzle. By investigating the influence of the deposition temperature, information could be obtained on the formation mechanism of CaP coatings-and specifically the biologically interesting carbonate apatite phase-using the ESD technique. CaP coatings were not formed merely because of solvent evaporation; a chemical reaction was needed to synthesize the coatings. This reaction involved thermal decomposition of the organic solvent butyl carbitol into carbonate ions via formation of intermediate oxalate ions. The amount of carbonate incorporation, and consequently, the Ca/P ratios of the deposited coatings, was shown 1) to decrease with increasing nozzleto-substrate distance, 2) to decrease with increasing liquid flow rate, and 3) to decrease by making use of a novel two-component nozzle geometry.
IEEE Transactions on Industry Applications, 2003
Back corona on a powder layer deposited via the electrostatic powder-coating process using corona guns has a strong influence on the corrosion resistance and appearance of cured powder films. The presence of the back corona is often evidenced by orange peel, micro-dents, and pinholes on the film surface. The surface resistivity of the sprayed powder governs the charge decay process and, hence, the onset of back corona. The polymer powders used in powder coating are highly resistive, with surface resistivity often greater than 10 15 . Surface resistivity can be altered by the adsorption of moisture on the surfaces of the powder particles. The objectives of this research were: 1) investigate the effect of decreasing surface resistivity on the appearance of the powder-coated film and 2) enhance hydrophilic properties of polymer powder by plasma treatment. By changing the relative humidity (RH) of powder during the spraying process, it was observed that the surface resistivity could be lowered by orders of magnitude. For example, the surface resistivity for an acrylic powder decreased from 2.96 10 13 at 25% RH to 9.6 10 11 at 70% RH. The plasma treatment of this powder further improved its charge decay properties. The effects of variation of RH on the appearance of powder-coated panels surface layer are presented for an acrylic polymer powder. The film texture has been characterized by microstructural surface analysis using an optical scanning instrument. Methods of plasma and corona treatments of the powder for increasing moisture adsorption on the surface and decreasing surface resistivity are discussed along with analysis of surface morphology using the atomic force microscope.