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Effect of casting solvent and polymer on permeability of propranolol hydrochloride through membrane controlled transdermal drug delivery system  [cached]
Murthy T.E.G.K,Kishore V
Indian Journal of Pharmaceutical Sciences , 2007,
Abstract: In the present work, cellulose acetate and ethyl cellulose films were prepared and evaluated as rate controlling membrane for transdermal drug delivery systems. In each case films were prepared using solutions of the polymer in various solvents to evaluate the influence of the solvent used on the mechanical and permeability properties of the films. Acetone-methanol (8:2), chloroform-methanol (8:2), dichloromethane-methanol (8:2) and ethyl acetate-methanol (8:2) were used as solvents in the preparation of cellulose acetate and ethyl cellulose films. Dibutyl phthalate or propylene glycol at a concentration of 40% w/w of the polymer was used as a plasticizer in the preparation films. The method of moulding was found to be giving thin uniform films. The dry films were evaluated for physical appearance, thickness uniformity, folding endurance, water vapour transmission, drug diffusion and permeability coefficient. Both water vapour transmission and Drug diffusion rate followed zero order kinetics. The mechanism of drug release was governed by Peppas model. The diffusion exponent of release profiles (slope) has a value of 1.0360-1.3147 (n>1), which indicates non anomalous transport diffusion. The results obtained in the present study thus indicated that the polymers and solvents used in the preparation of films have shown significant influence on the water vapour transmission, drug diffusion and permeability of the films. Area of patches ranging from 1.29- 4.53 cm 2 were found to yield the desired release rate of propranolol hydrochloride. Cellulose acetate films employed with ethyl acetate:methanol in 8:2 ratio as casting solvent yielded low area (1.29 cm 2 ) of patch with desired release rate.
Water dispersible microbicidal cellulose acetate phthalate film
A Neurath, Nathan Strick, Yun-Yao Li
BMC Infectious Diseases , 2003, DOI: 10.1186/1471-2334-3-27
Abstract: CAP and hydroxypropyl cellulose (HPC) were dissolved in different organic solvent mixtures, poured into dishes, and the solvents evaporated. Graded quantities of a resulting selected film were mixed for 5 min at 37°C with HIV-1, HSV and other STD pathogens, respectively. Residual infectivity of the treated viruses and bacteria was determined.The prerequisites for producing CAP films which are soft, flexible and dispersible in water, resulting in smooth gels, are combining CAP with HPC (other cellulose derivatives are unsuitable), and casting from organic solvent mixtures containing ≈50 to ≈65% ethanol (EtOH). The films are ≈100 μ thick and have a textured surface with alternating protrusions and depressions revealed by scanning electron microscopy. The films, before complete conversion into a gel, rapidly inactivated HIV-1 and HSV and reduced the infectivity of non-viral STD pathogens >1,000-fold.Soft pliable CAP-HPC composite films can be generated by casting from organic solvent mixtures containing EtOH. The films rapidly reduce the infectivity of several STD pathogens, including HIV-1. They are converted into gels and thus do not have to be removed following application and use. In addition to their potential as topical microbicides, the films have promise for mucosal delivery of pharmaceuticals other than CAP.Polymers, used in the past as pharmaceutical excipients and in drug delivery, are increasingly being considered for specific therapeutic and prophylactic applications [1-5]. They appear promising for topical applications as microbicides to prevent infection by sexually transmitted disease (STD) pathogens, including the human immunodeficiency virus (HIV-1) [6]. One of these promising polymeric microbicides is cellulose acetate phthalate (CAP) [7-14]. CAP has been used for enteric film coating of tablets and capsules [15] and thus has a well-established safety record for human use. CAP is not soluble in water at pH <≈5.8. For this reason, it must be used in a
Water dispersible microbicidal cellulose acetate phthalate film
Neurath A,Strick Nathan,Li Yun-Yao
BMC Infectious Diseases , 2003,
Abstract: Background Cellulose acetate phthalate (CAP) has been used for several decades in the pharmaceutical industry for enteric film coating of oral tablets and capsules. Micronized CAP, available commercially as "Aquateric" and containing additional ingredients required for micronization, used for tablet coating from water dispersions, was shown to adsorb and inactivate the human immunodeficiency virus (HIV-1), herpesviruses (HSV) and other sexually transmitted disease (STD) pathogens. Earlier studies indicate that a gel formulation of micronized CAP has a potential as a topical microbicide for prevention of STDs including the acquired immunodeficiency syndrome (AIDS). The objective of endeavors described here was to develop a water dispersible CAP film amenable to inexpensive industrial mass production. Methods CAP and hydroxypropyl cellulose (HPC) were dissolved in different organic solvent mixtures, poured into dishes, and the solvents evaporated. Graded quantities of a resulting selected film were mixed for 5 min at 37°C with HIV-1, HSV and other STD pathogens, respectively. Residual infectivity of the treated viruses and bacteria was determined. Results The prerequisites for producing CAP films which are soft, flexible and dispersible in water, resulting in smooth gels, are combining CAP with HPC (other cellulose derivatives are unsuitable), and casting from organic solvent mixtures containing ≈50 to ≈65% ethanol (EtOH). The films are ≈100 μ thick and have a textured surface with alternating protrusions and depressions revealed by scanning electron microscopy. The films, before complete conversion into a gel, rapidly inactivated HIV-1 and HSV and reduced the infectivity of non-viral STD pathogens >1,000-fold. Conclusions Soft pliable CAP-HPC composite films can be generated by casting from organic solvent mixtures containing EtOH. The films rapidly reduce the infectivity of several STD pathogens, including HIV-1. They are converted into gels and thus do not have to be removed following application and use. In addition to their potential as topical microbicides, the films have promise for mucosal delivery of pharmaceuticals other than CAP.
Effect of casting solvent and polymer on permeability of propranolol hydrochloride through membrane-controlled transdermal drug delivery system  [cached]
Gopala Krishna Murthy Talasila,Saikishore Vankayalapati
Asian Journal of Pharmaceutics , 2008,
Abstract: In the present work, cellulose acetate (CA), ethyl cellulose (EC), and Eudragit RS 100 (ERS100) films were prepared and evaluated as rate-controlling membranes for transdermal drug delivery systems. Acetone-methanol (8:2), chloroform-methanol (8:2), dichloromethane-methanol (8:2), and ethyl acetate-methanol (8:2) were used as solvents in the preparation of films. Dibutyl phthalate or propylene glycol at a concentration of 40% w/w of the polymer was used as a plasticizer in the preparation of CA and EC films. Dibutyl phthalate at a concentration of 15% w/w of the polymer was used as a plasticizer in the preparation of ERS100 films. The solvent evaporation technique was employed for the preparation of CA and EC films, and the casting solvent technique was employed for the preparation of ERS100 films. The dry films were evaluated for physical appearance, thickness uniformity, folding endurance, water vapor transmission (WVT), drug diffusion, and permeability coefficient. Both WVT and drug diffusion rate followed zero-order kinetics. The mechanism of drug release was governed by Peppas model. The diffusion exponent of release profiles (slope) has a value of 1.0360-1.3147 ( n > 1), which indicates super case II transport diffusion. The results obtained in the present study thus indicated that the polymers and solvents used for the preparation of films have shown significant influence on the WVT, drug diffusion, and permeability of the films.
Impact of Biofield Treatment on Chemical and Thermal Properties of Cellulose and Cellulose Acetate
Mahendra Kumar Trivedi, Gopal Nayak, Shrikant Patil, Rama Mohan Tallapragada, Rakesh Mish
Bioengineering & Biomedical Science , 2015, DOI: 10.4172/2155-9538.1000162
Abstract: Cellulose being an excellent biopolymer has cemented its place firmly in many industries as a coating material, textile, composites, and biomaterial applications. In the present study, we have investigated the effect of biofield treatment on physicochemical properties of cellulose and cellulose acetate. The cellulose and cellulose acetate were exposed to biofield and further the chemical and thermal properties were investigated. X-ray diffraction study asserted that the biofield treatment did affect the crystalline nature of cellulose. The percentage of crystallite size was found increased significantly in treated cellulose by 159.83%, as compared to control sample. This showed that biofield treatment was changing the crystalline nature of treated cellulose. However treated cellulose acetate showed a reduction in crystallite size (-17.38%) as compared to control sample. Differential Scanning Calorimetry (DSC) of treated cellulose showed no improvement in melting temperature as compared to control sample. Contrarily cellulose acetate showed significant improvement in melting temperature peak at 351.91oC as compared to control (344oC) polymer. Moreover percentage change in latent heat of fusion (ΔH) was calculated from the DSC thermogram of both treated and control polymers. A significant increase in percentage ΔH of both treated cellulose (59.09%) and cellulose acetate (105.79%) polymers indicated that biofield treatment enhanced the thermal stability of the treated polymers. CHNSO analysis revealed a significant change in percentage hydrogen and oxygen of treated cellulose (%H-17.77, %O-16.89) and cellulose acetate (%H-5.67, %O-13.41). Though minimal change was observed in carbon percentage of both treated cellulose (0.29%) and cellulose acetate (0.39%) polymers as compared to their respective control samples. Thermo gravimetric analysis and Differential thermo gravimetric (TGA-DTG) analysis of treated cellulose acetate (353oC) showed increased maximum thermal decomposition temperature as compared to control polymer (351oC). This showed the higher thermal stability of the treated cellulose acetate polymer; although the maximum thermal decomposition temperature of treated cellulose (248oC) was decreased as compared to control cellulose (321oC). These outcomes confirmed that biofield treatment has changed the physicochemical properties of the cellulose polymers.
Cellulose acetate as solid phase in ELISA for plague
Barbosa, AD;Barros, FSM de;Callou, EQ;Almeida, AMP;Araujo, AM;Azevedo, WM;Carvalho Jr, LB;
Memórias do Instituto Oswaldo Cruz , 2000, DOI: 10.1590/S0074-02762000000100015
Abstract: antigen from yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. elisa for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 μg of antigen, 3,200 times diluted positive serum using human anti-igg conjugate diluted 1:4,000. no relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. the discs were impregnated by the coloured products from the elisa development allowing its use in dot-elisa. furthermore, cellulose acetate showed a better performance than the conventional pvc plates.
Cellulose acetate as solid phase in ELISA for plague  [cached]
Barbosa AD,Barros FSM de,Callou EQ,Almeida AMP
Memórias do Instituto Oswaldo Cruz , 2000,
Abstract: Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 μg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates.
The Kinetics of Cellulose Grafting with Vinyl Acetate Monomer
éva Borbély
Acta Polytechnica Hungarica , 2005,
Abstract: Cellulose is a natural raw material recurring in a great quantity. The demand touse it more and more widely is increasing. The production of cellulose derivates started asearly as the 19th century, however the modification of these materials meant the breakingup the fibrous structure, which made their use more difficult in paper industry. Themodified cellulose made by graft copolymerization, however, keeps its fibrous character,which provides a great advantage regarding its use. Grafting of industrial cellulose pulpwith vinyl-acetate allows for the production of grafted wood cellulose fibres that have athermoplastic layer on their surface. The binder fibre (fibrid) produced in this way can beexcellently used for producing synthetic papers.In the first part of my experiments I dealt with choosing the parameters of graftcopolymerization which are best suited to various uses and after that I studied thedependence of graft reaction on the composition and properties of industrial celluloseapplied. The selection of the suitable reaction parameters was followed by the study ofreaction speed and activation energy. I have stated that the gross reaction of graftingindustrial cellulose with vinyl-acetate monomer is a second order reaction, which is provenby the fact that the invert of the momentary monomer concentration of the system plottedagainst time is a linear function. The rise of the curves, that is, the reaction speed increaseswhen the temperature in the range of 293–323 K is increasing, while the average activationenergy decreases.
Addressing Cellulose Acetate Microfilm from a British Library perspective  [cached]
Helen Shenton
Liber Quarterly : The Journal of European Research Libraries , 2005,
Abstract: This paper is about cellulose acetate microfilm from the British Library perspective. It traces how acetate microfilm became an issue for the British Library and describes cellulose acetate deterioration. This is followed by details of what has already been done about the situation and what action is planned for the future.
CELLULOSE ACETATE MEMBRANES WITH ADJUSTABLE PORE SIZE
Guerrero,R. F. E; Talavera,R. R; Meneses,V. M. C;
Revista Latinoamericana de Metalurgia y Materiales , 2002,
Abstract: in this work a description about the behavior of the porosity in membranes made from cellulose acetate and polyacrylic acid were carried out. in this description a mathematical model which describes the variation of the diameter of the pores was obtained. the results shows that the size of the pores vary as a function of the time employed during a thermal treatment. to obtain the mathematical model experimental data were analyzed by the use of the software graphical analysis.
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