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.
How to monitor HPMC concentration through conductivity measurement / Zakhvatayeva, Anastasiya; Pirera, Pietro; Resta, Alessandro; De Angelis, Maria Grazia; De Carolis, Carlo. - In: PHARMACEUTICAL TECHNOLOGY. - ISSN 1543-2521. - STAMPA. - 41:10(2017), pp. 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.
