A comparison of capillary and rotational viscometry of aqueous solutions of hypromellose
A comparison of capillary and rotational viscometry of gentle pseudoplastic solutions of hypromellose (HPMC 4000) by using only single-point value of viscosity is difficult. Single-point comparison becomes topical in consequence to the pharmacopoeial requirement that the apparent viscosity
of 2% hypromellose solution should be read at the shear rate of approximately 10 s–1. This communication is focused on the estimation of the suitable shear rate, Dη, at which the apparent viscosity read using the rotational viscometer is numerically equal
to the dynamic viscosity read using a capillary viscometer. For the solutions of HPMC in concentrations up to 2% w/v, the non-linear regression equations generated showed the influencing of the Dη value by the dynamic viscosity and/or by the originally derived linear
velocity of the solution flowing through the capillary viscometer tube. To compare the apparent viscosity read using the rotational viscometer with the dynamic viscosity read using capillary viscometer, the exact estimation of the shear rate Dη at which both viscosities are
numerically equal is essential since it is markedly affected by the concentration of HPMC solution.
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Document Type: Research Article
Department of Pharmaceutical Technology, Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Heyrovského 1203, Hradec Králové, 500 05, Czech Republic, Email: [email protected]
Department of Pharmaceutical Technology, Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Hradec Králové, Czech Republic
Publication date: 01 October 2007
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Pharmazie is a leading journal in the field of pharmaceutical sciences. As a peer-reviewed scientific journal, Pharmazie is regularly indexed in the relevant databases like Web of science, Journal Citation Reports and many others. The journal is open for submissions from the whole spectrum of pharnaceutical sciences including Pharmaceutical Chemistry, Experimental and Clinical Pharmacology, Drug Analysis, Pharmaceutics, Pharmaceutical Biology, Clinical Pharmacy etc.
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