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Robert O Williams - One of the best experts on this subject based on the ideXlab platform.
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properties of heat humidity cured Cellulose Acetate Phthalate free films
European Journal of Pharmaceutical Sciences, 2002Co-Authors: Jiping Liu, Robert O WilliamsAbstract:Abstract Cellulose Acetate Phthalate (CAP) free films containing diethyl Phthalate (DEP) or triethyl citrate (TEC) as the plasticizer were prepared by the spray method. The chemical and mechanical properties of films were compared following heat-only (50 °C for 24 h) and heat-humidity curing (50 °C/75% RH for 24 h) conditions. The surface roughness of the heat-humidity cured films decreased compared to that of the uncured and heat-only cured films. The heat-humidity curing condition suppressed evaporation of the plasticizer, resulting in higher plasticizer levels remaining in the films, as compared to the heat-only curing condition. The heat-humidity curing also significantly increased the mechanical strength and decreased the water vapor permeability of the films. When exposed to the acidic media, despite rapid leaching of plasticizer, the heat-humidity cured films retained the most mechanical strength of the films prior to exposure. The moisture content and phthalic acid content after heat-humidity curing were increased slightly, but did not reach a level that would interfere with enteric performance. TEC was less volatile and produced films with increased % elongation, and decreased tensile strength and elastic modulus compared to the films plasticized with DEP. However, the DEP plasticized films were less permeable than TEC-plasticized films following heat-humidity curing. The results indicated that a short-term exposure of the CAP films to heat and humidity during the curing process greatly improved the degree of film coalescence and mechanical strength, without causing significant chemical degradation of the polymer.
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long term stability of heat humidity cured Cellulose Acetate Phthalate coated beads
European Journal of Pharmaceutics and Biopharmaceutics, 2002Co-Authors: Jiping Liu, Robert O WilliamsAbstract:The objective of this study was to investigate the influence of stability storage conditions on the enteric release of heat-humidity cured Cellulose Acetate Phthalate (CAP) coated beads. Theophylline beads were coated with 25 or 35% diethyl Phthalate plasticized CAP dispersion (Aquacoat CPD), and cured at a heat-humidity condition (50 degrees C/75% RH) for 24h. The cured beads were then stored in various container/closure systems (open glass containers, sealed glass containers with and without desiccant) and exposed to 40 degrees C/75% RH for 6 months or 25 degrees C/60% RH for 12 months. At accelerated conditions (40 degrees C/75% RH), only beads stored in sealed glass containers with desiccant displayed stable release profiles throughout the exposure period. The beads stored in sealed glass containers without desiccant showed increased theophylline release in acidic media at 2h, and did not maintain enteric resistance at 6 months. The release profiles of beads stored in open containers, directly exposed to 40 degrees C/75% RH, were the least stable. The decrease in enteric protection of the beads stored at these two packaging conditions was correlated to an increased phthalic acid content in the films. At ambient storage conditions (25 degrees C/60% RH), all samples possessed enteric release properties, irrespective of the container/closure system. Beads stored in sealed glass containers with desiccant remained the most stable compared to those at the other two packaging conditions. The results indicated that although humidity significantly contributed to coalescence of CAP coating during the curing process, the optimum packaging condition for the heat-humidity cured CAP coated beads was with desiccant to maintain the chemical stability of the CAP.
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the influence of plasticizer on heat humidity curing of Cellulose Acetate Phthalate coated beads
Pharmaceutical Development and Technology, 2001Co-Authors: Robert O Williams, Jiping LiuAbstract:The objectives of the present study are to investigate the effect of plasticizer type and level on the curing of Cellulose Acetate Phthalate (CAP) coated beads with and without the presence of humidity. Theophylline beads were coated in a fluidized-bed with CAP dispersion (Aquacoat CPD) plasticized by a water-insoluble plasticizer, diethyl Phthalate (DEP), or a water-soluble plasticizer, triethyl citrate (TEC), at various levels. The coated heads were cured at a heat-only condition (50 degrees C for 24 hr) and a heat-humidity condition (50 degrees C/75% RH for 24 hr). Rapid drug release in the acidic media was found for both heat-only and heat-humidity cured beads when plasticizer was not used in the coating dispersion, indicating that the heat-humidity curing is ineffective without the presence of plasticizers. When plasticizer was incorporated in the coating formulations, heat-humidity curing effectively improved the acid resistance of the coated films at all plasticizer levels investigated. The minimum plasticizer level required to obtain enteric release profiles for heat-humidity cured beads coated at an outlet coating temperature of 46 degrees C was 15%. This limit was further decreased when the beads were coated at a lower temperature due to a less plasticizer loss at the lower coating temperature. Between the two plasticizers, less TEC was lost during the coating process, and TEC was more effective compared to DEP with regards to heat-humidity curing at the 10% plasticizer level. The enteric release profiles were reproducible following a 7-day drying period at 40 degrees C for all heat-humidity cured beads that had initially passed the enteric release dissolution test. The rapid leaching of TEC and DEP into the.
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influence of processing and curing conditions on beads coated with an aqueous dispersion of Cellulose Acetate Phthalate
European Journal of Pharmaceutics and Biopharmaceutics, 2000Co-Authors: Robert O Williams, Jiping LiuAbstract:Abstract The influence of fluidized-bed processing conditions, as well as curing parameters with and without humidity, on drug release from beads coated with Cellulose Acetate Phthalate (CAP) aqueous dispersion was investigated. Theophylline beads prepared by extrusion–spheronization were coated with diethyl Phthalate (DEP)-plasticized CAP dispersion (Aquacoat ® CPD) using a Strea-1 fluidized-bed coater. The parameters investigated were plasticizer level, outlet temperature, spray rate during coating application and fluidizing air velocities using a half-factorial design. The processing temperature during coating applications was identified as a critical factor among the variables investigated. The release rate significantly decreased when the beads were coated at 36°C compared to those coated at 48°C ( P
Jiping Liu - One of the best experts on this subject based on the ideXlab platform.
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properties of heat humidity cured Cellulose Acetate Phthalate free films
European Journal of Pharmaceutical Sciences, 2002Co-Authors: Jiping Liu, Robert O WilliamsAbstract:Abstract Cellulose Acetate Phthalate (CAP) free films containing diethyl Phthalate (DEP) or triethyl citrate (TEC) as the plasticizer were prepared by the spray method. The chemical and mechanical properties of films were compared following heat-only (50 °C for 24 h) and heat-humidity curing (50 °C/75% RH for 24 h) conditions. The surface roughness of the heat-humidity cured films decreased compared to that of the uncured and heat-only cured films. The heat-humidity curing condition suppressed evaporation of the plasticizer, resulting in higher plasticizer levels remaining in the films, as compared to the heat-only curing condition. The heat-humidity curing also significantly increased the mechanical strength and decreased the water vapor permeability of the films. When exposed to the acidic media, despite rapid leaching of plasticizer, the heat-humidity cured films retained the most mechanical strength of the films prior to exposure. The moisture content and phthalic acid content after heat-humidity curing were increased slightly, but did not reach a level that would interfere with enteric performance. TEC was less volatile and produced films with increased % elongation, and decreased tensile strength and elastic modulus compared to the films plasticized with DEP. However, the DEP plasticized films were less permeable than TEC-plasticized films following heat-humidity curing. The results indicated that a short-term exposure of the CAP films to heat and humidity during the curing process greatly improved the degree of film coalescence and mechanical strength, without causing significant chemical degradation of the polymer.
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long term stability of heat humidity cured Cellulose Acetate Phthalate coated beads
European Journal of Pharmaceutics and Biopharmaceutics, 2002Co-Authors: Jiping Liu, Robert O WilliamsAbstract:The objective of this study was to investigate the influence of stability storage conditions on the enteric release of heat-humidity cured Cellulose Acetate Phthalate (CAP) coated beads. Theophylline beads were coated with 25 or 35% diethyl Phthalate plasticized CAP dispersion (Aquacoat CPD), and cured at a heat-humidity condition (50 degrees C/75% RH) for 24h. The cured beads were then stored in various container/closure systems (open glass containers, sealed glass containers with and without desiccant) and exposed to 40 degrees C/75% RH for 6 months or 25 degrees C/60% RH for 12 months. At accelerated conditions (40 degrees C/75% RH), only beads stored in sealed glass containers with desiccant displayed stable release profiles throughout the exposure period. The beads stored in sealed glass containers without desiccant showed increased theophylline release in acidic media at 2h, and did not maintain enteric resistance at 6 months. The release profiles of beads stored in open containers, directly exposed to 40 degrees C/75% RH, were the least stable. The decrease in enteric protection of the beads stored at these two packaging conditions was correlated to an increased phthalic acid content in the films. At ambient storage conditions (25 degrees C/60% RH), all samples possessed enteric release properties, irrespective of the container/closure system. Beads stored in sealed glass containers with desiccant remained the most stable compared to those at the other two packaging conditions. The results indicated that although humidity significantly contributed to coalescence of CAP coating during the curing process, the optimum packaging condition for the heat-humidity cured CAP coated beads was with desiccant to maintain the chemical stability of the CAP.
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the influence of plasticizer on heat humidity curing of Cellulose Acetate Phthalate coated beads
Pharmaceutical Development and Technology, 2001Co-Authors: Robert O Williams, Jiping LiuAbstract:The objectives of the present study are to investigate the effect of plasticizer type and level on the curing of Cellulose Acetate Phthalate (CAP) coated beads with and without the presence of humidity. Theophylline beads were coated in a fluidized-bed with CAP dispersion (Aquacoat CPD) plasticized by a water-insoluble plasticizer, diethyl Phthalate (DEP), or a water-soluble plasticizer, triethyl citrate (TEC), at various levels. The coated heads were cured at a heat-only condition (50 degrees C for 24 hr) and a heat-humidity condition (50 degrees C/75% RH for 24 hr). Rapid drug release in the acidic media was found for both heat-only and heat-humidity cured beads when plasticizer was not used in the coating dispersion, indicating that the heat-humidity curing is ineffective without the presence of plasticizers. When plasticizer was incorporated in the coating formulations, heat-humidity curing effectively improved the acid resistance of the coated films at all plasticizer levels investigated. The minimum plasticizer level required to obtain enteric release profiles for heat-humidity cured beads coated at an outlet coating temperature of 46 degrees C was 15%. This limit was further decreased when the beads were coated at a lower temperature due to a less plasticizer loss at the lower coating temperature. Between the two plasticizers, less TEC was lost during the coating process, and TEC was more effective compared to DEP with regards to heat-humidity curing at the 10% plasticizer level. The enteric release profiles were reproducible following a 7-day drying period at 40 degrees C for all heat-humidity cured beads that had initially passed the enteric release dissolution test. The rapid leaching of TEC and DEP into the.
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influence of processing and curing conditions on beads coated with an aqueous dispersion of Cellulose Acetate Phthalate
European Journal of Pharmaceutics and Biopharmaceutics, 2000Co-Authors: Robert O Williams, Jiping LiuAbstract:Abstract The influence of fluidized-bed processing conditions, as well as curing parameters with and without humidity, on drug release from beads coated with Cellulose Acetate Phthalate (CAP) aqueous dispersion was investigated. Theophylline beads prepared by extrusion–spheronization were coated with diethyl Phthalate (DEP)-plasticized CAP dispersion (Aquacoat ® CPD) using a Strea-1 fluidized-bed coater. The parameters investigated were plasticizer level, outlet temperature, spray rate during coating application and fluidizing air velocities using a half-factorial design. The processing temperature during coating applications was identified as a critical factor among the variables investigated. The release rate significantly decreased when the beads were coated at 36°C compared to those coated at 48°C ( P
S Sridhar - One of the best experts on this subject based on the ideXlab platform.
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potential of extraction of steviol glycosides using Cellulose Acetate Phthalate cap polyacrylonitrile pan blend hollow fiber membranes
Journal of Food Science and Technology-mysore, 2015Co-Authors: Anirban Roy, Siddhartha Moulik, S SridharAbstract:Cellulose Acetate Phthalate (CAP) – Polyacrylonitrile (PAN) blend hollow fibers were spun in the present work and their efficacy in extraction of Steviol glycosides was investigated. Various compositions of blend hollow fibers were characterized in terms of scanning electron microscopy (SEM), permeability, contact angle, pore size distribution and breaking stress. Concentration of CAP was varied up to 5 wt.% in a total polymer concentration of 20 wt.%. It was observed from SEM images that finger like pores in the cross-section became tear drop like with decrease in concentration of CAP, making them denser. Pure PAN membrane showed the highest permeability around 238 l/m2.h.bar and the lowest molecular weight cut off (MWCO) 12 kDa and the highest pore density 2.8 × 1018 m−2. CAP-PAN (4:16) blend membrane of MWCO 30 kDa was found to be the most suitable for extraction of Steviol glycosides. At 34 kPa transmembrane pressure drop (TMP) and cross flow rate (CFR) 10 l/h, glycoside recovery was 55 % and purity was 30 % under total recycle mode of operation. Steady state permeate flux was 8 l/m2.h at 102 kPa TMP. A three stage diafiltration was carried out at 34 kPa TMP and 5 l/h flow. Enhanced 94 % recovery and 54 % purity of the Steviol glycosides was obtained under these conditions.
Anirban Roy - One of the best experts on this subject based on the ideXlab platform.
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solvent effect and macrovoid formation in Cellulose Acetate Phthalate cap polyacrylonitrile pan blend hollow fiber membranes
Journal of Applied Polymer Science, 2017Co-Authors: Anirban Roy, Prasenjit BhuniaAbstract:The interactions which govern the morphology of blend hollow fiber membranes is explored in detail in the present work. A hydrophilic (Cellulose Acetate Phthalate) and a relatively hydrophobic polymer (polyacrylonitrile, critical surface tension 47.0 mJ/m2) blend in three solvents, viz., n-methylpyrrolidone (NMP), dimethyl formamide (DMF), and dimethylsulfoxide (DMSO), has been selected as an example to understand the polymeric blend—solvent and nonsolvent interactions. The deviation intrinsic parameter ( Δ[η]) is estimated as well as cloud point, linearized cloud point (LCP), and Fourier transform-infrared (FT-IR) analysis have been performed for the blend membranes. The analysis yields that Δ[η] is negative for both DMF and NMP indicating miscibility, whereas for DMSO it is positive indicating immiscibility. Cloud point and LCP analysis too reveal DMSO to be the poorest solvent and liquid-liquid demixing is the governing phenomenon for the phase inversion. In depth interaction is conducted with help of FT-IR spectra. The higher red shift of >C==O (1747 to 1665 cm−1) after complete phase inversion indicates stronger interaction in DMF and NMP, whereas, no shift in >C==O stretching in DMSO indicates weak or no interaction. This reveals that polymer blend-solvent interaction is weak in case of DMSO than DMF or NMP. These observations manifest in DMSO membranes being most porous, with highest permeability and molecular weight cut off with poor tensile strength. On the other hand, NMP and DMF hollow fiber membranes yields denser structure with better mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44366.
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potential of extraction of steviol glycosides using Cellulose Acetate Phthalate cap polyacrylonitrile pan blend hollow fiber membranes
Journal of Food Science and Technology-mysore, 2015Co-Authors: Anirban Roy, Siddhartha Moulik, S SridharAbstract:Cellulose Acetate Phthalate (CAP) – Polyacrylonitrile (PAN) blend hollow fibers were spun in the present work and their efficacy in extraction of Steviol glycosides was investigated. Various compositions of blend hollow fibers were characterized in terms of scanning electron microscopy (SEM), permeability, contact angle, pore size distribution and breaking stress. Concentration of CAP was varied up to 5 wt.% in a total polymer concentration of 20 wt.%. It was observed from SEM images that finger like pores in the cross-section became tear drop like with decrease in concentration of CAP, making them denser. Pure PAN membrane showed the highest permeability around 238 l/m2.h.bar and the lowest molecular weight cut off (MWCO) 12 kDa and the highest pore density 2.8 × 1018 m−2. CAP-PAN (4:16) blend membrane of MWCO 30 kDa was found to be the most suitable for extraction of Steviol glycosides. At 34 kPa transmembrane pressure drop (TMP) and cross flow rate (CFR) 10 l/h, glycoside recovery was 55 % and purity was 30 % under total recycle mode of operation. Steady state permeate flux was 8 l/m2.h at 102 kPa TMP. A three stage diafiltration was carried out at 34 kPa TMP and 5 l/h flow. Enhanced 94 % recovery and 54 % purity of the Steviol glycosides was obtained under these conditions.
Satish K Singh - One of the best experts on this subject based on the ideXlab platform.
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thermal and mechanical characterization of Cellulose Acetate Phthalate films for pharmaceutical tablet coating effect of humidity during measurements
Drug Development and Industrial Pharmacy, 1998Co-Authors: Anders Karlsson, Satish K SinghAbstract:AbstractFilms from a polymer used in pharmaceutical coating (Cellulose Acetate Phthalate) were analyzed by thermomechanical techniques including dynamic mechanical thermal analysis (DMTA) and tensile tests. Emphasis was placed on relative humidity (RH) at the measurement site (as opposed to storage or conditioning RH). The films were plasticized with either triethyl citrate or diethyl Phthalate. The results show that the films respond rapidly to changes in the environmental humidity. This in turn influences the data obtained from DMTA and tensile testing; thus, good control of the humidity is essential. Absorption isotherms have been obtained for the two types of films, and the results were interpreted in terms of the equilibrium moisture content which is determined by the polar nature of the plasticizer. This factor must be considered when formulating a film composition because moisture can, apart from its influence on mechanical properties, also speed the chemical degradation processes. When the stabili...
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characterization of Cellulose Acetate Phthalate cap
Drug Development and Industrial Pharmacy, 1998Co-Authors: Pernilla Roxin, Anders Karlsson, Satish K SinghAbstract:Cellulose Acetate Phthalate (CAP) is a commonly used enteric coating polymer. CAP powder has been studied by various methods to determine characteristics that have an influence on its functionality. While some of the parameters are well known, such as free-acid content and substituent composition, new methods have been developed to examine them. Other characteristics, such as the molecular mass distribution, have not been reported earlier. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and thermal analysis have also been performed on fresh samples, as well as samples stored under various temperature and humidity conditions. Humidity is by far a more critical storage parameter than temperature, although the two act in conjunction; high humidity is more deleterious to the functionality of the polymer than high temperature. Functionality in this case is taken to be determined by the substituents and by the molecular mass distribution. Mass-average molecular mass of a number of batches of the polymer has been measured and ranges around 48 kg/mol with a degree of polydispersity of 1.6. A method to perform a rough estimation of the molecular mass of CAP has also been suggested based on knowledge of the substituent content. It may be possible to use the values of and obtained here for any other batch of the same viscosity grade of CAP. NMR has been employed to determine the fraction substituents in the polymer. However, an attempt to obtain the pattern of substitution of the CAP molecule by NMR was unsuccessful. Glass transition temperatures of CAP samples were measured. However, this characteristic of the polymer is judged not as sensitive to the loss of substituents as the molecular mass. Thermal treatment of the polymer in oxygen and inert atmospheres gave slightly different degradation products.