Concentration Of Carbopol Research Articles

Investigation of certain varieties of carbopol in ketorolac tromethamine hydrophilic matrix tablet formulations and evaluation of the kinetics of its in vitm release

Matrix tablets of ketorolac trometharnine (KT) were prepared by direct compression technique and Carbopol 934, 940 and 1342 have been used as polymers in different concentrations (5-15 % ). For the quality control of tablets; physical tests as crushing strength, diameter-height ratio and fkiability, KT amount assay and in vitro dissolution techniques were performed and dissolution profiles were plotted and evaluated kinetically. The in vitro release kinetics of ten different formulations of KT matrix tablet were studied at pH 1.2 and pH 7.0 using the USP dissolution technique and apparatus with basket assembly. Dissolution results were evaluated kinetically and statistically. According to our results, different types and concentrations of carbopol to tablet formulations may effect in controlled drug release.

Application of a factorial design to the study of the flow behavior, spreadability and transparency of a Carbopol ETD 2020 gel. Part II

A factorial design (2 3) is applied to study the influence of three of the components of a cosmetic gel (the concentrations of Carbopol ETD 2020, ethanol and glycerine) on flow parameters (Casson's yield value ( τ c), Casson's viscosity ( η c) and apparent viscosity at 125 s −1 ( η ap. 125 s −1)), spreadability, and transparency. The first-order polynomial equation allowed by the model suitably accounts for the τ c and spreadability. Both depend on the concentrations of Carbopol and ethanol, and τ c also depends on the ethanol–glycerine interaction. The model explains to a certain extent the complex relationships that are established between the components and that influence η c y η ap. 125 s −1. Transparency is independent of the Carbopol concentration and it is also thought to be independent of the ethanol concentration. In addition, a high linear correlation has been found between the τ c and spreadability and other viscoelastic parameters of the gels that were previously determined (Int. J. Pharm. (2001)). The application of the technique of experimental design has been shown to be a very useful tool for formulating gels.

New measurements of the flow-curves for Carbopol dispersions without slip artefacts

The thickening properties of many commercial thickeners are difficult to measure because of wall slip artefacts. Here we report a series of experiments on a typical thickener where these artefacts have been successfully eliminated. As a result, complete, steady-state flow-curves of aqueous Carbopol 980 (the toxicologically preferred version of the older and more well-known Carbopol 940) dispersions are reported for a range of concentrations of 0.045–1.0 wt%. The vane-and-basket flow geometry was used to avoid slip problems at low shear stress, with the geometry housed in a TA AR1000-N controlled-stress rheometer, whilst a Haake RV2 viscometer with an SV2P and MV2P concentric-cylinder geometries were used at higher shear rates. The flow-curves obtained show a smooth but steep transition from a very high Newtonian viscosity at low shear stress to a much lower viscosity at high shear stress. No real yield stresses were detected, but the higher shear rate results can be fitted to the Herschel-Bulkley model, which assumes an apparent yield stress. The various model parameters are displayed as a function of Carbopol concentration.

Rheological evaluation of the interactions between cationic celluloses and Carbopol 974P in water.

This paper reports on the influence of the structural properties of two cationic hydroxyethylecelluloses, polyquaternium-4 (PQ-4; 1.13-1.27% N) and polyquaternium-10 (PQ-10; 1.88-1.95% N), on the rheological behavior of their dispersions and of the dispersions of their blends with Carbopol 974P (60.9% COOH) in water. Dynamic shear oscillation measurements showed that the rheological behavior of 1 and 2% (w/w) cellulose polymers was mainly viscous. Flow curves of PQ-10 dispersions presented a higher consistency and pseudoplasticity than PQ-4 dispersions, in which the thixotropy was higher. Structural features, such as type and distribution of substituents and molecular weight, explain why they behave different. The presence of 0.00125-0.02% Carbopol in diluted cationic cellulose (0.01-0.08%) dispersions produced an important decrease in viscosity, due to a strong associative process via an electrostatic interaction phenomenon. Similar results were obtained when sodium acetate was added instead of Carbopol. In contrast, in the concentrated range (1% cellulose polymer), the viscous (G") and especially the elastic (G') moduli of the dispersions increased monotonically with Carbopol concentration (0.010-0.125%) and became physical gels, except in the proximity of the neutralization of the ammonium groups (0.07% Carbopol for PQ-4, and 0.1% Carbopol for PQ-10) in which G" and G' decreased. The concentrated dispersions showed pH-sensitivity when the Carbopol added was around or above the neutralization point. In dispersions with this composition, consistency increased dramatically when pH changed from 4.5 to 7.4. This property can open a wide range of applications, especially in the pharmaceutical field to prepare gelling in situ systems.

Mucoadhesive and Physicochemical Characterization of Carbopol-Poloxamer Gels Containing Triamcinolone Acetonide

The viscosity and bioadhesive property of Carbopol-Poloxamer gels containing triamcinolone acetonide to mucosa were tested according to various concentrations of Carbopol gels of various pH. The increase in Carbopol concentration caused increased viscosity and bioadhesiveness. The neutralization of pH in various concentrations of Carbopol gels showed the increased viscosity, showing the highest viscosity and highest bioadhesiveness when neutralized to pH 6. A relationship between the viscosity and bioadhesive strength was shown from the neutralized Carbopol gels. The physicochemical interactions between triamcinolone acetonide and polymers were investigated by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectrophotometry. According to FTIR and XRD studies, the drug did not show any evidence of an interaction with the polymers used and was present in an unchanged state.

Noninvasive measurement of protein release from subcutaneous depo formulations in vivo using X-ray fluorescence

The feasibility of using radioisotope-induced X-ray fluorescence (XRF) as a noninvasive method to measure the release rate of peptides/proteins from hydrogels or other formulations in vivo following subcutaneous administration has been demonstrated. A sodium phosphate buffer solution (PBS) containing 52 mg/ml of iodinated bovine serum albumin (I-BSA) was administered subcutaneously in female Sprague-Dawley rats and the administration site was fluoresced at regular intervals over a 24–96 h period. The variation in the iodine X-ray yield with time indicated that the disappearance of I-BSA alone followed first order kinetics with a half-life of approximately 6.6 h. When the I-BSA was formulated into a polymeric hydrogel of poly(acrylic acid) (Carbopol-940), a significant increase in the half-life was observed. As the Carbopol concentration was increased from 5.61 to 18.75 mg/ml, the disappearance half-life increased from 6.3 to 14.0 h. Free iodide loaded into the Carbopol gel at equivalent concentrations had a disappearance half-life of 13.8 min.

Interaction of polyacrylates with porcine pepsin and the gastric mucus barrier: a mechanism for mucosal protection.

1. The mechanism of interaction of the polyacrylates, carbopols with the mucus barrier in vivo has been investigated in vitro. 2. Carbopol caused a dramatic increase in the viscosity of porcine gastric mucin solutions that was up to 19-fold greater than that of the sum of the individual polymers. 3. The mucin-carbopol interaction was stable after an initial 30 min period for up to 36 h at 25 degrees C or 37 degrees C. It was reduced by increasing the temperature from 20 degrees C to 45 degrees C, was unaffected by pH and ionic strength, but was enhanced by Ca2+. 4. The magnitude of the interaction between mucin and carbopol depended on the polymeric structure of the mucin and the molecular size and level of cross-linking of the carbopol. 5. The interactions were reversible and increased with increasing carbopol and mucin concentration. The dramatic increase in viscosity can be explained in terms of space filling by the mucin molecules leading to predominantly carbopol-carbopol interactions. 6. Carbopol 934P inhibits pepsin hydrolysis and therefore has potential as a mucosal protective agent in vivo.

Evaluation of carbopol 934 as a suspending agent for sulphaoimidine suspensions

The suitability of carbopol 934 as a suspending agent was investigated by continuous shear and creep analysis using a concentric cylinder air turbine viscometer. Apparent vistosities determined from the apices of flow curves at a constant shear rate of 87 s −1 varied little with temperature over the range of 10–50°C. Decrease in pH from 8 to 6 caused a reduction in apparent viscosity. Non-Newtonian, pseudoplastic-like flow curves with little hysteresis were obtained for 0.1–3% w/v neutralized carbopol 934 dispersions, the magnitude of their apparent static yield value being linearly related to the polymer concentration. Analysis of creep compliance curves for carbopol dispersions showed that the material was a viscoelastic liquid at 0.5 and 1% and a viscoelastic solid at 3%. Suspensions containing 10% w/v sulphadimidine and variable concentration of carbopol 934 gave qualitatively similar rheological results. Permanent suspensions after 6 months storage at room temperature were obtained for sulphadimidine suspensions using 0.3% or greater carbopol 934. Accelerated sedimentation tests on sulphadimidine—carbopol suspensions involving centrifugal techniques correlated well with the results of longterm sedimentation studies. Measurement of apparent static yield values and apparent viscosities at 87 s −1 of such suspensions were also found useful for predicting their longterm sedimentation appearance.

Inhibition of RNA-dependent DNA polymerase of oncorna viruses by Carbopol 934

FEBS LettersVolume 52, Issue 1 p. 141-144 Full-length articleFree Access Inhibition of RNA-dependent DNA polymerase of oncorna viruses by Carbopol 934 H.P.J. Bloemers, H.P.J. Bloemers Department of Biochemistry, University ofnijmegen, Geert Grooteplein Noord 21, Nijmegen, The NetherlandsSearch for more papers by this authorA. van der Horst, A. van der Horst Department of Biochemistry, University ofnijmegen, Geert Grooteplein Noord 21, Nijmegen, The NetherlandsSearch for more papers by this author H.P.J. Bloemers, H.P.J. Bloemers Department of Biochemistry, University ofnijmegen, Geert Grooteplein Noord 21, Nijmegen, The NetherlandsSearch for more papers by this authorA. van der Horst, A. van der Horst Department of Biochemistry, University ofnijmegen, Geert Grooteplein Noord 21, Nijmegen, The NetherlandsSearch for more papers by this author First published: March 15, 1975 https://doi.org/10.1016/0014-5793(75)80657-0Citations: 5AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL References 1 Clercq E. De, P.J. Claes, Biochim. Biophys. Acta, 331, (1973), 329– 332. 2 T.S. Papas, T.W. Pry, M.A. Chirigos, Proc. Natl. Acad. Sci. U.S.A., 71, (1974), 367– 370. 3 W. Braun, W. Regelson, Y. Yajima, M. Ishizuka, Proc. Soc. Exp. Biol. Med., 133, (1970), 171– 175. 4 W. Regelson, Advan. Exp. Med. Biol., 1, (1967), 315– 332. 5 M.A. Chirigos, Comparative Leukemia Research, 36, (1970), 278– 292. Bibl. Haemat. 6 M.A. Chirigos, W. Turner, J. Pearson, W. Griffin, Int. J. Cancer, 4, (1969), 267– 278. 7 I.M. Verma, D. Baltimore, Methods in Enzymology XXIX (1974), Academic Press New York, London 125– 143. 8 H.C. Chopra, G.P. Shibley, J. Nat. Cancer Inst., 39, (1967), 241– 256. 9 D. Baltimore, D. Smoler, Proc. Natl. Acad. Sci. U.S.A., 68, (1971), 1507– 1511. 10 T.H. Maugh, Science, 184, (1974), 970– 974. 11 M. Linial, W.S. Mason, Virology, 53, (1973), 258– 273. Citing Literature Volume52, Issue1March 15, 1975Pages 141-144 ReferencesRelatedInformation

Carbon dioxide solubility in aqueous carbopol solutions at 24.deg., 30.deg., and 35.deg.

Solubilities for carbon dioxide in 0.25, 0.75, and 1.00% by wt aqueous Carbopol (carboxy polymethylene) solutions are determined at 24/sup 0/, 30/sup 0/, and 35/sup 0/C. The rheological behavior of these solutions can be described by the Ostwald-de Waele power-law model with the flow behavior index varying between 0.916 and 0.594. The solubilities are expressed in terms of Henry's Law and decrease with increasing Carbopol concentration and temperature.

Formulation and Evaluation of pH Induced In-situ Nasal Gel of Salbutamol Sulphate

Nasal solutions of Salbutamol Sulphate were prepared for sustaining its release and improving its bioavailability. Carbopol was used as a key ingredient to effect pH induced sol to gel conversion of the formulations. Different formulations were prepared by varying the concentrations of Carbopol 934 and Hydroxyl Propyl Methyl Cellulose. These formulations were evaluated for parameters like pH, drug content, viscosity, gel strength and drug release. Release profile of some formulations showed rapid phase while some showed slow phase. At extreme low concentrations of the polymers, the formulations drained out due to poor viscosity while at higher concentrations of the same the formulations formed stiff gel and showed slow release of drug. Finally optimized formulation with specific concentrations of carbopol 934 and Hydroxyl Propyl Methyl Cellulose showed pH induced sol-gel conversion, sustained release and higher bioavailability

A reassessment of the wall effect of non-newtonian flow of polymer solutions

An apparatus for checking slip interpretation of flow anomalies in the laminar capillary flow of macromolecular solutions is described. It consists of a two-dimensional flow channel, having a uniform width of 1.5 inch and an alternative, convergent taper that is adjustable. Dilute aqueous solutions of the polymers Carbopol, Natrosol, and Polyox are recirculated in steady laminar flow from a large reservoir. Velocities, pressures, and wall shear stresses are measured. Local velocities are obtained by the local injection of conductive tracer fluid, whose passage is sensed by sets of electrodes stationed along the flow. Wall shear stresses are measured on a small, freely displaceable, traction surface flush with the channel wall. The tests cover concentrations of Carbopol of 0.1% to 0.4%, Natrosol of 0.5% to 1%, and Polyox of 0.5% to 1%. Approximate viscosities range from about 10 to 1000 cP. Wall shear rates up to 1000 s−1 are attained.