title: Evaluation of ethylcellulose and its pseudolatex (Surelease) in preparation of matrix pellets of theophylline using extrusion-spheronization.
abstract: OBJECTIVE
  This study evaluates the effect of substitution of microcrystalline cellulose (MCC) with ethylcellulose (EC) on mechanical and release characteristics of theophylline pellets.
  
  
  METHODS
  The effect of addition of EC was investigated on characteristics of pellets with varying drug content prepared by extrusion-spheronization. Also the effect of type of granulating liquid (water or Surelease) was investigated on characteristics of selected pellets. The pellets were characterized for particle size (sieve analysis), mechanical strength, morphology (microscopy), thermal (DSC) and dissolution behaviors.
  
  
  RESULTS
  The exrtudability of the wet mass was reduced upon inclusion of EC so that complete replacement of MCC was not possible. Increase in EC percentage led to lower production yield and formation of pellets with larger diameter and slightly rough surfaces. Inclusion of EC also affected the mechanical properties of pellets but had negligible effect on drug release profile. The surface of selected pellets became smoother and their production yield increased upon the use of Surelease as granulating liquid. In addition the rate of drug release decreased to some extent when Surelease was used.
  
  
  CONCLUSIONS
  Preparation of theophylline pellets with EC alone was not possible in process of extrusion-spheronization. Partial replacement of MCC with EC changed physicomechanical properties of pellets but hardly affected drug release. Although the use of Surelease as granulation liquid slightly decreased the rate of drug release, desirable matrix pellets with sustained drug release could not be produced. Despite this outcome however, these pellets could benefit from reduced coating thickness for drug release control.
authors.affiliation: Pharmaceutical Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; Department of Pharmaceutics, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Hadi Afrasiabi
authors.initials: HA
authors.lastname: Garekani
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Roshanak
authors.initials: R
authors.lastname: Dolatabadi
authors.affiliation: Targeted Drug Delivery Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; Department of Pharmaceutics, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Akhgari
authors.affiliation: Targeted Drug Delivery Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; Department of Pharmaceutics, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Abbaspour
authors.affiliation: Targeted Drug Delivery Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; Department of Pharmaceutics, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Sadeghi
keywords: Drug release; Ethylcellulose; Extrusion-spheronization Pellet; Surelease; Theophylline