A study of shear and compression deformations on hydrophilic gels of α-tocopherol

Lucero, M.J.; Vigo, Jean; León, M.J.

doi:10.1016/0378-5173(94)90349-2

Cited by 5 publications

(2 citation statements)

References 13 publications

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“…This can be explained by concentration-dependent effects on the formulations' viscosity. In the literature, Lucero et al 43 and Jones et al 44 have described a correlation between a formulation's viscosity and its mechanical properties. In our study, the formulation coded "F8+SLN" exhibited the greatest cohesiveness and adhesiveness values, thus offered optimal performance in this regard.…”

Section: Discussionmentioning

confidence: 99%

A new approach to the treatment of recurrent aphthous stomatitis with bioadhesive gels containing cyclosporine A solid lipid nanoparticles: in vivo/in vitro examinations

Karavana¹,

Gökçe²,

Rençber³

et al. 2012

IJN

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Aim:To develop a suitable buccal bioadhesive gel formulation containing cyclosporine A solid lipid nanoparticles (CsA SLNs) for the treatment of recurrent aphthous stomatitis. Methods: The suitability of the prepared formulations for buccal application was assessed by means of rheological studies, textural profile analysis, and ex vivo drug-release studies. Plastic flows, typical gel-like spectra, and suitable mechanical properties were obtained from prepared formulations. The retention time was explored in in vivo distribution studies and the effect of the gel containing CsA SLNs on the healing of oral mucosal ulceration was investigated in an animal model. In vivo distribution studies are a very important indicator of the retention time of formulations at the application site. Results: Distribution studies showed that 64.76% ± 8.35% of the formulation coded "F8+SLN" remained on the buccal mucosa 6 hours after application. For the second part of the in vivo experiments, 36 rabbits were separated into three groups: the first group was treated with the gel formulation without the active agent; the second group with the gel formulation containing CsA SLNs; and the third group, used as the control group, received no treatment. Wound healing was established by scoring of the rate of wound healing on Days 3, 6, 9, and 12. Histological observations were made on the same days as the scoring studies. The bioadhesive gel formulation that included CsA SLNs increased the rate of mucosal repair significantly. Conclusion: This study has shown that the bioadhesive gel formulation containing CsA SLNs reported here is a promising candidate for the topical treatment of recurrent aphthous stomatitis.

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Section: Discussionmentioning

confidence: 99%

A new approach to the treatment of recurrent aphthous stomatitis with bioadhesive gels containing cyclosporine A solid lipid nanoparticles: in vivo/in vitro examinations

Karavana¹,

Gökçe²,

Rençber³

et al. 2012

IJN

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“…In organogels containing 10% w/w polymer, there is less free solvent available to facilitate drug solubility, and therefore, competition for secondary interactions occurs. To facilitate metronidazole solubilization, solvent–polymer bonds may have been compromised, and accordingly, the solubilization of metronidazole dislodged solvent molecules from the polymer chains, which resulted in a more intramolecularly bonded (or randomly coiled) structure and, consequently, a decrease in formulation storage modulus and loss modulus was observed. , Furthermore, the observed reduction in formulation viscoelastic properties of the PAA organogels in the presence of the higher concentration of drug may be attributed, at least in part, to the ability of the drug substance to interact with the PAA chains, resulting in a disruption of the viscoelastic network. This has been previously reported for aqueous PAA gels …”

Section: Discussionmentioning

confidence: 99%

Physicochemical Characterization of Bioactive Polyacrylic Acid Organogels as Potential Antimicrobial Implants for the Buccal Cavity

et al. 2008

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This study describes the formulation and physicochemical characterization of poly(acrylic acid) (PAA) organogels, designed as bioactive implants for improved treatment of infectious diseases of the oral cavity. Organogels were formulated containing a range of concentrations of PAA (3-10% w/w) and metronidazole (2 or 5% w/w, representing a model antimicrobial agent) in different nonaqueous solvents, namely, glycerol (Gly), polyethylene glycol (PEG 400), or propylene glycol (PG). Characterization of the organogels was performed using flow rheometry, compressional analysis, oscillatory rheometry, in vitro mucoadhesion, moisture uptake, and drug release, methods that provide information pertaining to the nonclinical and clinical use of these systems. Increasing the concentration of PAA significantly increased the consistency, compressibility, storage modulus, loss modulus, dynamic viscosity, mucoadhesion, and the rate of drug release. These observations may be accredited to enhanced molecular polymer entanglement. In addition, the choice of solvent directly affected the physicochemical parameters of the organogels, with noticeable differences observed between the three solvents examined. These differences were accredited to the nature of the interaction of PAA with each solvent and, importantly, the density of the resultant physical cross-links. Good correlation was observed between the viscoelastic properties and drug release, with the exception of glycerol-based formulations containing 5 and 10% w/w PAA. This disparity was due to excessive swelling during the dissolution analysis. Ideally, formulations should exhibit controlled drug release, high viscoelasticity, and mucoadhesion, but should flow under minimal stresses. Based on these criteria, PEG 400-based organogels composed of 5% or 10% w/w PAA exhibited suitable physicochemical properties and are suggested to be a potentially interesting strategy for use as bioactive implants designed for use in the oral cavity.

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Rheological destructuring of aqueous gels composed of cellulose ethers following storage in the presence of redox agents

Jones

Muldoon

Woolfson

et al. 2005

J of Applied Polymer Sci

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ABSTRACT:Despite their widespread use, there is a paucity of information concerning the effect of storage on the rheological properties of pharmaceutical gels that contain organic and inorganic additives. Therefore, this study examined the effect of storage (1 month at either 4 or 37°C) on the rheological and mechanical properties of gels composed of either hydroxypropylmethylcellulose (3-5% w/w, HPMC) or hydroxyethylcellulose (3-5% w/w, HEC) and containing or devoid of dispersed organic (tetracycline hydrochloride 2% w/w) or inorganic (iron oxide 0.1% w/w) agents. The mechanical properties were measured using texture profile analysis whereas the rheological properties were analyzed using continuous shear rheometry and modeled using the Power Law model. All formulations exhibited pseudoplastic flow with minimal thixotropy. Increasing polymer concentration (3-5% w/w) significantly increased the consistency, hardness, compressibility, and adhesiveness of the formulations due to increased polymer chain entanglement. Following storage (1 month at 4 and 37°C) the consistency and mechanical properties of additive free HPMC gels (but not HEC gels) increased, due to the time-dependent development of polymer chain entanglements. Incorporation of tetracycline hydrochloride significantly decreased and increased the rheological and mechanical properties of HPMC and HEC gels, respectively. Conversely, the incorporation of iron oxide did not affect these properties. Following storage, the rheological and mechanical properties of HPMC and HEC formulations were markedly compromised. This effect was greater following storage at 37 than at 4°C and, additionally, greater in the presence of tetracycline hydrochloride than iron oxide. It is suggested that the loss of rheological/mechanical structure was due to chain depolymerization, facilitated by the redox properties of tetracycline hydrochloride and iron oxide. These observations have direct implications for the design and formulation of gels containing an active pharmaceutical ingredient.

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A study of shear and compression deformations on hydrophilic gels of α-tocopherol

Cited by 5 publications

References 13 publications

A new approach to the treatment of recurrent aphthous stomatitis with bioadhesive gels containing cyclosporine A solid lipid nanoparticles: in vivo/in vitro examinations

A new approach to the treatment of recurrent aphthous stomatitis with bioadhesive gels containing cyclosporine A solid lipid nanoparticles: in vivo/in vitro examinations

Physicochemical Characterization of Bioactive Polyacrylic Acid Organogels as Potential Antimicrobial Implants for the Buccal Cavity

Rheological destructuring of aqueous gels composed of cellulose ethers following storage in the presence of redox agents

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