title: Study of the critical points and the role of the pores and viscosity in carbamazepine hydrophilic matrix tablets.
abstract: Percolation theory has been applied to estimate the Hypromellose (HPMC) percolation thresholds and the influence of the polymer viscosity and the initial porosity on these thresholds in carbamazepine multicomponent matrix formulations. Different batches containing two viscosity grades of HPMC as hydrophilic matrix forming polymer, MCC and lactose as fillers, and a lubricant mixture have been manufactured varying the compression pressure in order to obtain matrices with three levels of initial porosity. The results suggested the existence of an excipient percolation threshold between 13 and 15% v/v of HPMC for the different batches prepared. It has been found that the percolation threshold for this polymer is independent on the formulation factors studied in this paper: polymer viscosity and initial porosity of the matrices.
authors.affiliation: Department of Pharmacy and Pharmaceutical Technology, University of Seville, Seville, Spain.
authors.forename: Angela
authors.initials: A
authors.lastname: Aguilar-de-Leyva
authors.forename: Celia
authors.initials: C
authors.lastname: Cifuentes
authors.forename: Ali R
authors.initials: AR
authors.lastname: Rajabi-Siahboomi
authors.forename: Isidoro
authors.initials: I
authors.lastname: Caraballo
mesh_terms: D002220:Carbamazepine / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical / Q000379:methods; D003692:Delayed-Action Preparations; D005079:Excipients / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D065347:Hypromellose Derivatives; D007700:Kinetics; D007785:Lactose / Q000737:chemistry; D008747:Methylcellulose / Q000031:analogs & derivatives / Q000737:chemistry; D010316:Particle Size; D011108:Polymers / Q000737:chemistry; D016062:Porosity; D013607:Tablets / Q000737:chemistry; D014783:Viscosity
chemical_list: D003692:Delayed-Action Preparations; D005079:Excipients; D011108:Polymers; D013607:Tablets; D002220:Carbamazepine; D065347:Hypromellose Derivatives; D008747:Methylcellulose; D007785:Lactose