J Carolina Visser1, Oekie A F Weggemans2, René J Boosman2, Katja U Loos3, Henderik W Frijlink2, Herman J Woerdenbag2. 1. Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands. Electronic address: j.c.visser@rug.nl. 2. Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands. 3. Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Abstract
The addition of enalapril maleate to a casting solution for orodispersible films (ODFs) containing hypromellose and carbomer 974P as film forming agents (standard casting solution, SCS) caused a dose dependent reduction of the viscosity. This phenomenon was a serious problem in the preparation of ODFs with an increased enalapril load (>1mg per ODF) when using the solvent casting method. The aim of the present work was twofold. Firstly, the influence of enalapril on the viscosity of SCS was studied in more detail. Secondly, two methods for increasing the enalapril load of an ODF were investigated that did not negatively influence the properties of SCS. The casting height was increased and the preparation of bilayered ODF, using the double-casting method, was explored. In the framework of the bilayered ODFs the compatibility between the film forming agents hydroxypropyl cellulose (HPC), sodium alginate (SA), hydroxyethyl cellulose (HEC) and the combination hypromellose-carbomer 974P (SCS) was investigated. RESULTS AND CONCLUSIONS: We found that enalapril concentration dependently reduced the pH, thereby negatively influencing the gel formation and the viscosity of SCS. An increased casting height did not result in a proportionally increased enalapril load. The enalapril load could be doubled when a bilayered ODF containing two layers of SCS was produced. Finally, not all combinations of film forming agents could be used for the preparation of bilayered ODFs. Besides, the sequence in which the different polymer layers were casted affected the appearance of the ODFs. In conclusion, the best formulations were produced with the polymer combinations SCS/SCS and SCS/HPC.
The addition of enalapril maleate to a casting solution for orodispersible films (ODFs) containing hypromellose and carbomer 974P as film forming agents (standard casting solution, SCS) caused a dose dependent reduction of the viscosity. This phenomenon was a serious problem in the preparation of ODFs with an increased enalapril load (>1mg per ODF) when using the solvent casting method. The aim of the present work was twofold. Firstly, the influence of enalapril on the viscosity of SCS was studied in more detail. Secondly, two methods for increasing the enalapril load of an ODF were investigated that did not negatively influence the properties of SCS. The casting height was increased and the preparation of bilayered ODF, using the double-casting method, was explored. In the framework of the bilayered ODFs the compatibility between the film forming agents hydroxypropyl cellulose (HPC), sodium alginate (SA), hydroxyethyl cellulose (HEC) and the combination hypromellose-carbomer 974P (SCS) was investigated. RESULTS AND CONCLUSIONS: We found that enalapril concentration dependently reduced the pH, thereby negatively influencing the gel formation and the viscosity of SCS. An increased casting height did not result in a proportionally increased enalapril load. The enalapril load could be doubled when a bilayered ODF containing two layers of SCS was produced. Finally, not all combinations of film forming agents could be used for the preparation of bilayered ODFs. Besides, the sequence in which the different polymer layers were casted affected the appearance of the ODFs. In conclusion, the best formulations were produced with the polymer combinations SCS/SCS and SCS/HPC.