comparison rheological parameter
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In this article, the influence of electrolytes on the viscosity of sterilized hydrogels containing 60 g/L of hydroxypropyl methylcellulose (HPMC 4000) was investigated. The electrolytes mostly used in ophthalmics were sodium chloride, pilocarpine hydrochloride, atropine sulphate, and scopolamine hydrobromide. The hydrogels were prepared by using stationary method with a long period of storage in the refrigerator following the steam sterilization. Cone and plate rotational viscometry readings were modeled by using the three-parameter power law, which was validated by regression coefficients in the range of 0.9980-0.9999. In comparison to the hydrogel without additives, the significant decrease in viscosity was observed in the presence of pilocarpine hydrochloride in concentrations of 10 g/L and 30 g/L. On the other hand, the addition of sodium chloride, atropine sulphate, and scopolamine hydrobromide resulted in increasing of viscosity of hydrogels. The differences were nonsignificant when the single-point rheological characteristic, the apparent viscosity eta100, was evaluated, in contrast to using the area under rheogram (AUR) data when the significant effect of sodium chloride could be proved. Therefore, in conclusion, the multipoint rheological AUR data could be recommended. In the investigation of gentle plastic rheograms, nevertheless, the allocation of the lower limit of the integration to yield value is emphasized, which prevents the integration of a negative portion of flow curve and, consequently, the lower values of AUR to be obtained.
In this work, the cone and plate rheological viscometry readings of the sterilized hydrogels of hypromellose 4000 (60 g/L) were investigated by using of the three-parameter Herschel a nd Bulkley powerlaw and the new empirical two-parameter model. In it, the independent variable of shear rate was transformed by logarithm and the dependent variable of shear stress by square root. The two-parameter model showed only non-significantly lower mean value of the coefficient of determination when compared with the results of the three-parameter power law model being of good promise in other investigation of the near pseudoplastic rheograms of hypromellose hydrogels. To express the influence of the addition of the isotonic concentration of sodium chloride and/or pilocarpine hydrochloride, respectively, on the viscosity of sterilized hydrogels of hypromellose, the area under rheogram (AUR) data was employed as a multi-point theological characteristic. No significant differences were noted between AUR calculated using three parameters of the power law model and those calculated using two parameters of the proposed one. The significant increase in viscosity was observed in the presence of the isotonic concentration of sodium chloride in comparison to the hydrogel without additives. In the opposite, the addition of the isotonic concentration of pilocarpine hydrochloride resulted in the significant viscosity decrease. In conclusion, the proposed empirical two-parameter model could be used as the rheological model in investigation of the near pseudoplastic rheograms of the sterilized hypromellose hydrogels.
- MeSH
- chemické modely MeSH
- chlorid sodný chemie MeSH
- farmaceutická technologie metody MeSH
- hydrogely MeSH
- methylcelulosa analogy a deriváty chemie MeSH
- pilokarpin chemie MeSH
- plocha pod křivkou MeSH
- reologie MeSH
- sterilizace MeSH
- viskozita MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
[Topical preparation for burns and its evaluation]
Študovali sa niektoré otázky súvisiace s formuláciou topického prípravku typu hydrokrému, určeneho na liečenie dermálnych popálenín. Hodnotilo sa sedem krémových základov, obsahujúcich Emulgátor E 2155, Polysorbát 80 a silikonové oleje. Ako liečivá sa použili karbizokaín, lidokaín, chlórhexidín a imunomodulačná látka glukán. Meraním povrchového napätia roztokov chlórhexi dinu a karbizokaínu sa nezistila interakcia medzi týmito liečivami. Liberačnými skúškami sa potvrdilo vyššie uvoľňovanie lidokaínu v porovnaní s karbizokaínom a chlórhexidínom. Prítomný silikonový olej neovplyvnil liberáciu karbizokaínu, podporil však uvoľňovanie lidokaínu a chlórhexidínu. Stanovením reologických parametrov sa zistilo, že prísada liečiv ovplyvňovala tokové vlastnosti krémov. Vhodnosť krémových základov sa posudzovsila aj na základe ich vysýchavosti.
The study focused on some problems connected with the formulation of the topical preparation of the hydrocream type, intended for the treatment of dermal bums. Seven cream bases containing Emulgator E 2155, Polysorbate 80 and silicone oils were evaluated. The employed dmgs included carbizocaine, lidocaine, chlorohexidine, and the immunomodulating substance glucan. A measurement of the surface tension of chlorohexidine and carbizocaine did not reveal interaction between these two drugs. Liberation tests confirmed a higher release of lidocaine in comparison with carbizocaine and chlorohexidine. The silicone oil present did not influence the release of carbizocaine, but it promoted the release of lidocaine and chlorohexidine. The determination of rheological parameters revealed that an addition of drugs influenced the flow properties of creams. The suitability of cream ointments was evaluated on the basis of their drying.
Byly sledovány základní reologické parametry synoviálních tekutin (ST) - smykové napětí a první rozdíl normálového napětí jako funkce rychlosti deformace. U všech ST byla rovněž stanovována koncentrace kyseliny hyaluronové (KH)jako hlavní složky ST. Měření byla prováděna se vzorky patologických ST (n = 120 vzorků ) různého původu, tj. zánětlivých (n = 60), degenerativních (n = 46) a posttraumatických (n = 14). Na podkladě závislosti mezi konzistencí tekutiny a indexem toku v Ostwald de Waelově mocninovém modelu a dynamické viskozity jako funkce koncentrace KH byly rozděleny všechny éíoumané ST do tří charakteristických skupin. Pro srovnání byla měření prováděna na několika typech rotačních viskozimetrů. Získaných výsledků lze použít jak k upřesnění revmatologické diagnostiky, tak i v užší oblasti biomechaniky a fyziatrie.
The basic rheological parameters of synovial Fluids Shear stress and first normal stress difference were measured as a function of shear rate. In addition, the concentration of hyaluronic acid as a main component of synovial fiuid was measured. Pathological synovial fluids were investigated (n = 120 samples) from various mnt diseases, i.e. inflammatory (n = 60), degenerative (n=46) and posttraumatic effusions (n = 14). The regression method between the consistency of fluid and the behaviur index according to the Ostwald de Waele /aw was assessed, because the dynamic viscosity as a function of the concentration of hyaluronic acid in synovial fluid significantly differs according to its etiology. The comparison between measurements on several commercial rheometers was made. The results obtained appear of importance in rheumatology diagnosis. as well as for a broader area of biomechanics and physiatry.
