Hydroalcoholic solutions of hydroxypropyl methylcellulose (HPMC) can be used in place of gelatin solutions to seal pharmaceutical capsules. The control of HPMC concentration is essential to ensure a complete, uniform, and stable capsule seal. Sealing solution concentration is usually monitored by measuring the solution viscosity through a viscometer. HPMC solutions, however, are pseudoplastic rather than Newtonian fluids, thus their viscosity depends not only on the solution concentration, but also on the shear rate applied during stirring and/or transfer of solution from one container to another. The authors demonstrate that a proper measure of HPMC solution concentration is its electrical conductivity rather than its viscosity. The correlation between concentration and conductivity was tested in the concentration range 12-25% and a mathematical expression was proposed for it. This correlation allows one to control and adjust the solution water/alcohol ratio using a conductivity measurement.
Zakhvatayeva, A., Pirera, P., Resta, A., De Angelis, M.G., De Carolis, C. (2017). How to monitor HPMC concentration through conductivity measurement. PHARMACEUTICAL TECHNOLOGY, 41(10), 46-52.
How to monitor HPMC concentration through conductivity measurement
De Angelis, Maria Grazia;
2017
Abstract
Hydroalcoholic solutions of hydroxypropyl methylcellulose (HPMC) can be used in place of gelatin solutions to seal pharmaceutical capsules. The control of HPMC concentration is essential to ensure a complete, uniform, and stable capsule seal. Sealing solution concentration is usually monitored by measuring the solution viscosity through a viscometer. HPMC solutions, however, are pseudoplastic rather than Newtonian fluids, thus their viscosity depends not only on the solution concentration, but also on the shear rate applied during stirring and/or transfer of solution from one container to another. The authors demonstrate that a proper measure of HPMC solution concentration is its electrical conductivity rather than its viscosity. The correlation between concentration and conductivity was tested in the concentration range 12-25% and a mathematical expression was proposed for it. This correlation allows one to control and adjust the solution water/alcohol ratio using a conductivity measurement.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
