Influence of aqueous medium on viscoelastic properties of carboxymethylcellulose sodium, hydroxypropyimethyl cellulose, and thermally pre-gelatinized starch gels

Michailova, Victoria; Titeva, St; Kotsilkova, Rumiana; Krusteva, E.; Minkov, E

doi:10.1016/s0927-7757(98)00608-6

Cited by 40 publications

(27 citation statements)

References 8 publications

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“…The release from film forming gel composed of Na CMC/CP (2:0.3%) was the highest compared to other gel formulations (98.7%). This result is in agreement with the previous finding [23]. At pH 6.8, the Na CMC gel has a loose structure where the weak gel structure determines the ability of the polymer chains to disentangle from the polymer network and to dissolve.…”

Section: In Vitro Release Studysupporting

confidence: 93%

“…The release of diclofenac sodium shown in figure 7 from film forming gel based on HPMC (4% w/w) and HPC (16% w/w) alone was higher than those containing both polymers (different concentrations of HPMC with fixed concentration of HPC (3% w/w)). This may be due to the differences in wettability between HPMC and HPC which led to a decrease in the entrance of water through the polymer [23]. The release from HPC (16% w/w) alone (75.7%) was higher than its combination with carbopol (37.7%).…”

Section: In Vitro Release Studymentioning

confidence: 98%

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Film forming gel for treatment of oral mucositis: In vitro studies.

Attia¹,

Badawy²

2010

Int J Drug delivery

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Oral mucositis is one of the main complications of non-surgical cancer treatments. The present work focuses on the treatment or reduction of oral mucositis by using combined mechanism by formation of physical barrier by forming a film to cover the oral ulcer and use of therapeutic agents, such as diclofenac sodium and ofloxacin separately or in combination. The selected polymers for film forming gel formulations are Hydroxypropylcellulose (HPC), hydroxypropyl methylcellulose (HPMC), sodium carboxymethylcellulose (Na CMC) and carbopol 940 (CP). The residence time in simulated buccal saliva was between 5.5 to 6 hours for all formulations. The in-vitro release data of the investigated drugs from the prepared formulations followed zero-order and diffusion mechanism. The permeability studies data revealed that diclofenac sodium showed higher permeability from Na CMC/CP (2:0.3%) than from HPMC 4%, while in case of ofloxacin higher permeability was shown from Na CMC/CP (2:0.3%) than from HPMC/HPC (2:3%). The permeation parameters for diclofenac sodium and ofloxacin in their combination do not depend on either viscosity or pH, they depend on the type of polymers used.

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Section: In Vitro Release Studysupporting

confidence: 93%

Section: In Vitro Release Studymentioning

confidence: 98%

Film forming gel for treatment of oral mucositis: In vitro studies.

Attia¹,

Badawy²

2010

Int J Drug delivery

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“…It can be seen that for all hydrogel formulations, G' was always much higher than G# over the whole frequency range, which was a characteristic feature of a 'strong' hydrogel [48]. G' values of all hydrogel samples increased slowly with the increasing test frequency, implying the hydrogels maintain a strong network structure [49]. The similar tendency of G# varying with the frequency was found, but G# showed weak dependency of frequency.…”

Section: Compressive Mechanical Properties 341 Unconfined Uniaxialmentioning

confidence: 52%

Effects of polymerization degree on recovery behavior of PVA/PVP hydrogels as potential articular cartilage prosthesis after fatigue test

Yan¹,

Xiong²,

Peng³

et al. 2016

Express Polym. Lett.

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Abstract. Poly (vinyl alcohol)/poly (vinyl pyrrolidone) (PVA/PVP) hydrogels with various polymerization degrees of PVA were synthesized by a repeated freezing-thawing method. The influence of polymerization degree on microstructure, water content, friction coefficient, compressive fatigue and recovery properties of PVA/PVP hydrogels were investigated. The results showed that higher polymerization degree resulted in larger compressive modulus and lower friction coefficient. The fatigue behaviors of PVA/PVP hydrogels were evaluated under sinusoidal compressive loading from 200 to 800 N at 5 Hz for up to 50 000 cycles. The unconfined uniaxial compressive tests of PVA/PVP hydrogels were performed before and after fatigue test. During the fatigue test, the height of the hydrogel rapidly decreased at first and gradually became stable with loading cycles. The compressive tangent modulus measured 0 h after fatigue was significantly larger than the values obtained before test, and then the modulus recovered to its original level for 48 h after test. However, the geometry of hydrogels could not return to the original level due to the creep effects. PVA/PVP hydrogels prepared with lower polymerization degree showed better recovery capability than that prepared with high polymerization degree.

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“…11,35,36) In this section a study of the hydration rate of the matrices has been carried out, in order to obtain more information about the critical points observed in the study of drug release.…”

Section: Study Of Water Uptake Profiles and Swelling Kineticsmentioning

confidence: 99%

Study of the Critical Points in Lobenzarit Disodium Hydrophilic Matrices for Controlled Drug Delivery

Miranda

Millán

Caraballo

2006

CHEMICAL & PHARMACEUTICAL BULLETIN

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The hydrophilic matrices are one of the most used types of Controlled Release Systems in the world. In comparison with other Controlled Release Devices, they have the advantage of their low cost and simple technology, that facilitates their application to an important sector of the population, as well as their safety against the dose dumping (accidental fast release of the whole drug dose).1) Another advantage of these matrices concerns the drug release kinetics. Using these systems, it is possible to obtain a variety of release kinetics, including in some cases zero-order release kinetics.2)The study of hydrophilic matrices is a difficult task due to its complex and disordered structure. A number of publications have reported studies about the mechanisms of drug release from hydrophilic matrices. [3][4][5][6][7][8][9][10][11] In recent works, our research group has applied the percolation theory to study the release and hydration rate of hydrophilic matrices, in order to contribute to the rationalization of the design of these controlled release systems and to obtain a better knowledge of the processes that occur during the release of the drug. [12][13][14] Percolation Theory is a statistical theory that studies disordered or chaotic systems where the components are randomly distributed in a lattice. This theory has wide application in many scientific disciplines and was introduced by Leuenberger et al. in the pharmaceutical field in 1987 to improve the characterization of solid dosage forms. [15][16][17][18][19] Our research group is employing the percolation theory in order to describe solid forms, in concrete controlled release inert matrix systems. 15,16,[20][21][22][23][24][25][26] One of the most important parameters of percolation theory is the percolation threshold, where there is a maximum probability of appearance of an infinite or percolating cluster of a substance and some properties of the system change suddenly. A cluster is defined as a group of neighboring occupied sites in the lattice and is considered infinite or percolating when it extends from one side to the rest of the sides of the lattice, i.e. percolates the whole system. 27)The application of this theory to study the release and hydration rate of hydrophilic matrices allowed for first time to explain the changes in release and hydration kinetic of swellable matrices type controlled delivery systems. [12][13][14] According to this theory, the critical points observed in dissolution and water uptake studies can be attributed to the existence of excipient percolation thresholds. The knowledge of these thresholds is very important to optimize the design of swellable matrix tablets. Above the excipient percolation threshold an infinite cluster of this component is formed, controlling the hydration and release rate. Below this threshold the excipient does not percolate the system and, as a consequence, the drug release can not be controlled. It has to be emphasized that the infinite cluster of excipient responsible for the drug release contro...

show abstract

Influence of aqueous medium on viscoelastic properties of carboxymethylcellulose sodium, hydroxypropyimethyl cellulose, and thermally pre-gelatinized starch gels

Cited by 40 publications

References 8 publications

Film forming gel for treatment of oral mucositis: In vitro studies.

Film forming gel for treatment of oral mucositis: In vitro studies.

Effects of polymerization degree on recovery behavior of PVA/PVP hydrogels as potential articular cartilage prosthesis after fatigue test

Study of the Critical Points in Lobenzarit Disodium Hydrophilic Matrices for Controlled Drug Delivery

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