The Experts below are selected from a list of 2025 Experts worldwide ranked by ideXlab platform

Paul G. Royall - One of the best experts on this subject based on the ideXlab platform.

  • the effect of hydration on the thermal behaviour of hydrophilic non aqueous gels stabilised by Carbopol 974p
    Thermochimica Acta, 2004
    Co-Authors: Mustafa A. Zaman, Gary P. Martin, Gareth D. Rees, Paul G. Royall
    Abstract:

    A thermal analysis of the effect of hydration of non-aqueous polymer-stabilised gels was investigated using differential scanning calorimetry (DSC). The interaction of water with the polymer and its distribution within the gel are critical to the physicochemical behaviour of the gel, and consequently affects the utility of the gel matrix as a drug delivery vehicle. Addition of water at levels up to and including 50% (w/w) did not result in an observable freezing event in the thermogram. However, at 60 and 80% (w/w) water, phase transitions were observed, the magnitude of which were found to be independent of the annealing time within the range used. The observed melting enthalpies increased as the water concentration increased for all formulations, but were always smaller than that of pure water. There was no evidence of multiple transitions that might be attributed to different populations of water molecules. However, the results demonstrate that DSC can be employed to differentiate between freezable and non-freezable water, in these particular formulations.

  • The effect of hydration on the thermal behaviour of hydrophilic non-aqueous gels stabilised by Carbopol 974p ☆
    Thermochimica Acta, 2004
    Co-Authors: Mustafa A. Zaman, Gary P. Martin, Gareth D. Rees, Paul G. Royall
    Abstract:

    A thermal analysis of the effect of hydration of non-aqueous polymer-stabilised gels was investigated using differential scanning calorimetry (DSC). The interaction of water with the polymer and its distribution within the gel are critical to the physicochemical behaviour of the gel, and consequently affects the utility of the gel matrix as a drug delivery vehicle. Addition of water at levels up to and including 50% (w/w) did not result in an observable freezing event in the thermogram. However, at 60 and 80% (w/w) water, phase transitions were observed, the magnitude of which were found to be independent of the annealing time within the range used. The observed melting enthalpies increased as the water concentration increased for all formulations, but were always smaller than that of pure water. There was no evidence of multiple transitions that might be attributed to different populations of water molecules. However, the results demonstrate that DSC can be employed to differentiate between freezable and non-freezable water, in these particular formulations.

J P Remon - One of the best experts on this subject based on the ideXlab platform.

  • Influence of heat treatment on spray-dried mixtures of Amioca starch and Carbopol 974p used as carriers for nasal drug delivery.
    International journal of pharmaceutics, 2009
    Co-Authors: D Coucke, P Foreman, J P Remon, E Pringels, P Adriaensens, R Carleer, C Vervaet
    Abstract:

    A mucoadhesive spray-dried starch/poly(acrylic acid) powder underwent different heat treatments in order to induce cross-linking between the functional groups of starch (Amioca) and poly(acrylic acid) (Carbopol 974p). After heat treatment the water-absorbing capacity, viscosity and elasticity of the mucoadhesive powder increased. NMR analysis in combination with FT-IR indicated that heat treatment induced a low degree of cross-linking between the polymers. Nasal administration of Amioca/Carbopol 974p powders without heat treatment resulted in an absolute bioavailability in rabbits of 8.2+/-3.0% for insulin. Due to the difference in water-absorbing capacity (which opened the tight junctions of the nasal mucosa), elasticity and plasticity (which reduced mucociliairy clearance and prolonged residence time) heat treatment at 120 degrees C improved the bioavailability: 26.4+/-21.9, 36.5+/-11.0 and 19.3+/-17.3% after heat treatment during 30 min, 1 h and 4 h, respectively. Heat treatment at 60 degrees C was less efficient. This study demonstrated that the nasal insulin absorption improved via heat treatment of the Amioca/Carbopol 974p powder (prior to the addition of insulin). The bioavailability-enhancing effect of a 1 h heat treatment at 120 degrees C was confirmed using the same polymer matrix in combination with different drugs (salmon calcitonin, human growth hormone and metoprolol tartrate).

  • Influence of deposition and spray pattern of nasal powders on insulin bioavailability.
    International journal of pharmaceutics, 2006
    Co-Authors: E Pringels, P Foreman, C Vervaet, C Callens, F Dumont, G Slegers, J P Remon
    Abstract:

    The influence of the deposition pattern and spray characteristics of nasal powder formulations on the insulin bioavailability was investigated in rabbits. The formulations were prepared by freeze drying a dispersion containing a physical mixture of drum dried waxy maize starch (DDWM)/Carbopol 974p (90/10, w/w) or a spray-dried mixture of Amioca starch/Carbopol 974p (25/75, w/w). The deposition in the nasal cavity of rabbits and in a silicone human nose model after actuation of three nasal delivery devices (Monopowder, Pfeiffer and experimental system) was compared and related to the insulin bioavailability. Posterior deposition of the powder formulation in the nasal cavity lowered the insulin bioavailability. To study the spray pattern, the shape and cross-section of the emitted powder cloud were analysed. It was concluded that the powder bulk density of the formulation influenced the spray pattern. Consequently, powders of different bulk density were prepared by changing the solid fraction of the freeze dried dispersion and by changing the freezing rate during freeze drying. After nasal delivery of these powder formulations no influence of the powder bulk density and of the spray pattern on the insulin bioavailability was observed.

  • Spray-dried Amioca starch/Carbopol 974p mixtures as buccal bioadhesive carriers.
    International journal of pharmaceutics, 2005
    Co-Authors: D Ameye, D Mus, P Foreman, J P Remon
    Abstract:

    In the present study, spray-dried Amioca starch/Carbopol 974p mixtures were evaluated as potential buccal bioadhesive tablets. Carbopol (C 974p) concentrations from 5 to 75% were tested. All spray-dried mixtures showed a comparable or better bioadhesive capacity compared to a reference formulation (DDWM/C 974p 95/5). The bioadhesive capacities of Amioca/Carbopol 974p mixtures were improved by spray-drying. All spray-dried mixtures showed significantly higher work of adhesion values compared to their equivalent physical mixtures. The influence of Carbopol concentration on the in vivo adhesion time of placebo tablets and in vitro miconazole nitrate release was tested. The ratio Amioca/C 974p 70/30 showed the longest in vivo adhesion time (24.5+/-8.5 h). Lower and higher C 974p concentrations had a shorter in vivo adhesion time. The mixtures containing between 15 and 30% C 974p could all sustain the in vitro miconazole nitrate release over 20 h. Again, lower and higher C 974p concentrations showed a faster in vitro miconazole release. The drug loading capacity of a spray-dried mixture containing 20% C 974p was investigated in vivo in dogs using testosterone as model drug. The spray-dried mixture could be loaded with 60% drug without loosing its in vivo bioadhesive and pharmacokinetic properties.

  • spray dried amioca starch Carbopol 974p mixtures as buccal bioadhesive carriers
    International Journal of Pharmaceutics, 2005
    Co-Authors: D Ameye, D Mus, Paul B Foreman, J P Remon
    Abstract:

    Abstract In the present study, spray-dried Amioca ® starch/Carbopol ® 974p mixtures were evaluated as potential buccal bioadhesive tablets. Carbopol ® (C 974p) concentrations from 5 to 75% were tested. All spray-dried mixtures showed a comparable or better bioadhesive capacity compared to a reference formulation (DDWM/C 974p 95/5). The bioadhesive capacities of Amioca ® /Carbopol ® 974p mixtures were improved by spray-drying. All spray-dried mixtures showed significantly higher work of adhesion values compared to their equivalent physical mixtures. The influence of Carbopol ® concentration on the in vivo adhesion time of placebo tablets and in vitro miconazole nitrate release was tested. The ratio Amioca ® /C 974p 70/30 showed the longest in vivo adhesion time (24.5 ± 8.5 h). Lower and higher C 974p concentrations had a shorter in vivo adhesion time. The mixtures containing between 15 and 30% C 974p could all sustain the in vitro miconazole nitrate release over 20h. Again, lower and higher C 974p concentrations showed a faster in vitro miconazole release. The drug loading capacity of a spray-dried mixture containing 20% C 974p was investigated in vivo in dogs using testosterone as model drug. The spray-dried mixture could be loaded with 60% drug without loosing its in vivo bioadhesive and pharmacokinetic properties.

Steven H Neau - One of the best experts on this subject based on the ideXlab platform.

  • Use of к-carrageenan, chitosan and Carbopol 974p in extruded and spheronized pellets that are devoid of MCC
    Drug development and industrial pharmacy, 2016
    Co-Authors: Brenda L. Valle, Steven H Neau, Wycliffe Omwancha, Rodney J. Wigent
    Abstract:

    The search for excipients to replace microcrystalline cellulose (MCC) in the production of pellets by extrusion-spheronization in cases of drug incompatibility or the lack of pellet matrix disintegration forms the basis of this study. A combination of к-carrageenan as a spheronization aid, chitosan as a diluent and Carbopol(®) 974p as a binder in the production of pellets containing no MCC has been investigated using acetaminophen as a model drug. Design of experiments allowed assessment of formulation and processing effects on pellet responses that included size, shape, fines, yield and friability. Statistical analysis revealed that the main factors and some of the two-factor interactions had a significant effect on pellet characteristics. Formulations containing high levels of к-carrageenan required more water to produce a wetted mass with good extrudability and extrudate capable of being spheronized. Although only a low level of Carbopol was used in the formulation, it imparted cohesiveness to the wetted mass as well as the extrudate. Furthermore, it was discovered that Carbopol could act as an extrusion aid, enabling the wetted mass to flow easily through the extruder screen holes without building up heat. Spherical and rugged pellets were produced that met the immediate release criterion.

  • extruded and spheronized beads containing Carbopol 974p to deliver nonelectrolytes and salts of weakly basic drugs
    International Journal of Pharmaceutics, 2006
    Co-Authors: Ganesh S Bommareddy, Safak Pakerleggs, Kalyan K Saripella, Steven H Neau
    Abstract:

    The purpose of the study was to explore the utilization of Carbopol® 974p, NF, resin in a bead dosage form manufactured by extrusion and spheronization. It was possible to prepare beads in this study by using calcium chloride to overcome the tack problem associated with wetted Carbopol® 974p. The actives included both salts of weakly basic drugs (chlorpheniramine maleate and diphenhydramine hydrochloride) and nonelectrolytes (caffeine and dyphylline) which have a broad range of solubilities. Nonelectrolytes were released faster than the salts of weakly basic drugs. This is contrary to the behavior typically seen with a matrix system where the more soluble drug is released faster than a poorly soluble one. In the results of the present study, the solubility does not determine the drug release rate. Ionic interactions between the protonated amines of the salts and the carboxylates of the Carbopol resin are suggested to be the reason for the slower release of the salts of weakly basic drugs. Data from tack measurements confirm that this ionic interaction affects the behavior of the wetted Carbopol. In addition to the drug release profiles, bead average diameter, roundness, friability, and density were also determined.

  • formulation and process considerations for beads containing Carbopol 974p nf resin made by extrusion spheronization
    International Journal of Pharmaceutics, 2000
    Co-Authors: Steven H Neau, Michelle Y Chow, Gregory A Hileman, Manzer J Durrani, Ferdous Gheyas, Barry A Evans
    Abstract:

    Preliminary studies revealed that Carbopol 974p, NF resin could be incorporated into beads manufactured by extrusion and spheronization, and can slow the release of a highly water soluble drug if calcium chloride was included in the granulating fluid to reduce the tack of the wetted polymer. In this study, the same approach was used to produce high quality chlorpheniramine maleate beads with a prolonged release duration. Because of the complex nature of the extrusion and spheronization process and the various components in the bead formulations, a statistically sound factorial experiment was considered for this study. A one-half fraction of a two level factorial design with three center points was employed to estimate the effects of simultaneously modifying multiple process and formulation variables, including the Carbopol concentration, calcium chloride concentration, water content, and the spheronization speed and time. Product yield, average bead roundness, and the drug release profile were selected as responses. Increasing the Carbopol content across the experimental range resulted in a significant (P<0.05) reduction in the percentage drug released at 25, 40, and 60 min. Results suggest that combining the conditions of high Carbopol, high water, and low calcium chloride levels with low spheronization speeds at long spheronization times produce the highest quality bead with the longest drug release duration.

  • Formulation and process considerations for beads containing Carbopol 974p, NF resin made by extrusion-spheronization.
    International journal of pharmaceutics, 2000
    Co-Authors: Steven H Neau, Michelle Y Chow, Gregory A Hileman, Manzer J Durrani, Ferdous Gheyas, Barry A Evans
    Abstract:

    Preliminary studies revealed that Carbopol 974p, NF resin could be incorporated into beads manufactured by extrusion and spheronization, and can slow the release of a highly water soluble drug if calcium chloride was included in the granulating fluid to reduce the tack of the wetted polymer. In this study, the same approach was used to produce high quality chlorpheniramine maleate beads with a prolonged release duration. Because of the complex nature of the extrusion and spheronization process and the various components in the bead formulations, a statistically sound factorial experiment was considered for this study. A one-half fraction of a two level factorial design with three center points was employed to estimate the effects of simultaneously modifying multiple process and formulation variables, including the Carbopol concentration, calcium chloride concentration, water content, and the spheronization speed and time. Product yield, average bead roundness, and the drug release profile were selected as responses. Increasing the Carbopol content across the experimental range resulted in a significant (P

  • fabrication and characterization of extruded and spheronized beads containing Carbopol 974p nf resin
    International Journal of Pharmaceutics, 1996
    Co-Authors: Steven H Neau, Michelle Y Chow, Manzer J Durrani
    Abstract:

    Abstract Carbopol® 974p, NF resin is a synthetic, cross-linked, acrylic acid polymer. It becomes tacky when wetted, which introduces handling difficulties with techniques involving water or other fluid. To reduce tack, the water for wetting was replaced by an aqueous solution of a strong electrolyte. The effect of the concentration and type of electrolyte on the adhesive force of the wet mass was measured. A correlation was found between the charge density of the cation and the minimum salt concentration necessary to eliminate problems associated with tack. Beads containing chlorpheniramine maleate, Carbopol®, Avicel PH101, and electrolytes were successfully manufactured by extrusionspheronization. The Carbopol® concentration, as well as the pH and ionic strength of the dissolution medium and the rotation speed of the paddles, can modify drug release.

Mustafa A. Zaman - One of the best experts on this subject based on the ideXlab platform.

  • the effect of hydration on the thermal behaviour of hydrophilic non aqueous gels stabilised by Carbopol 974p
    Thermochimica Acta, 2004
    Co-Authors: Mustafa A. Zaman, Gary P. Martin, Gareth D. Rees, Paul G. Royall
    Abstract:

    A thermal analysis of the effect of hydration of non-aqueous polymer-stabilised gels was investigated using differential scanning calorimetry (DSC). The interaction of water with the polymer and its distribution within the gel are critical to the physicochemical behaviour of the gel, and consequently affects the utility of the gel matrix as a drug delivery vehicle. Addition of water at levels up to and including 50% (w/w) did not result in an observable freezing event in the thermogram. However, at 60 and 80% (w/w) water, phase transitions were observed, the magnitude of which were found to be independent of the annealing time within the range used. The observed melting enthalpies increased as the water concentration increased for all formulations, but were always smaller than that of pure water. There was no evidence of multiple transitions that might be attributed to different populations of water molecules. However, the results demonstrate that DSC can be employed to differentiate between freezable and non-freezable water, in these particular formulations.

  • The effect of hydration on the thermal behaviour of hydrophilic non-aqueous gels stabilised by Carbopol 974p ☆
    Thermochimica Acta, 2004
    Co-Authors: Mustafa A. Zaman, Gary P. Martin, Gareth D. Rees, Paul G. Royall
    Abstract:

    A thermal analysis of the effect of hydration of non-aqueous polymer-stabilised gels was investigated using differential scanning calorimetry (DSC). The interaction of water with the polymer and its distribution within the gel are critical to the physicochemical behaviour of the gel, and consequently affects the utility of the gel matrix as a drug delivery vehicle. Addition of water at levels up to and including 50% (w/w) did not result in an observable freezing event in the thermogram. However, at 60 and 80% (w/w) water, phase transitions were observed, the magnitude of which were found to be independent of the annealing time within the range used. The observed melting enthalpies increased as the water concentration increased for all formulations, but were always smaller than that of pure water. There was no evidence of multiple transitions that might be attributed to different populations of water molecules. However, the results demonstrate that DSC can be employed to differentiate between freezable and non-freezable water, in these particular formulations.

Gary P. Martin - One of the best experts on this subject based on the ideXlab platform.

  • the effect of hydration on the thermal behaviour of hydrophilic non aqueous gels stabilised by Carbopol 974p
    Thermochimica Acta, 2004
    Co-Authors: Mustafa A. Zaman, Gary P. Martin, Gareth D. Rees, Paul G. Royall
    Abstract:

    A thermal analysis of the effect of hydration of non-aqueous polymer-stabilised gels was investigated using differential scanning calorimetry (DSC). The interaction of water with the polymer and its distribution within the gel are critical to the physicochemical behaviour of the gel, and consequently affects the utility of the gel matrix as a drug delivery vehicle. Addition of water at levels up to and including 50% (w/w) did not result in an observable freezing event in the thermogram. However, at 60 and 80% (w/w) water, phase transitions were observed, the magnitude of which were found to be independent of the annealing time within the range used. The observed melting enthalpies increased as the water concentration increased for all formulations, but were always smaller than that of pure water. There was no evidence of multiple transitions that might be attributed to different populations of water molecules. However, the results demonstrate that DSC can be employed to differentiate between freezable and non-freezable water, in these particular formulations.

  • The effect of hydration on the thermal behaviour of hydrophilic non-aqueous gels stabilised by Carbopol 974p ☆
    Thermochimica Acta, 2004
    Co-Authors: Mustafa A. Zaman, Gary P. Martin, Gareth D. Rees, Paul G. Royall
    Abstract:

    A thermal analysis of the effect of hydration of non-aqueous polymer-stabilised gels was investigated using differential scanning calorimetry (DSC). The interaction of water with the polymer and its distribution within the gel are critical to the physicochemical behaviour of the gel, and consequently affects the utility of the gel matrix as a drug delivery vehicle. Addition of water at levels up to and including 50% (w/w) did not result in an observable freezing event in the thermogram. However, at 60 and 80% (w/w) water, phase transitions were observed, the magnitude of which were found to be independent of the annealing time within the range used. The observed melting enthalpies increased as the water concentration increased for all formulations, but were always smaller than that of pure water. There was no evidence of multiple transitions that might be attributed to different populations of water molecules. However, the results demonstrate that DSC can be employed to differentiate between freezable and non-freezable water, in these particular formulations.