title: Influence of plasticizer type and level on the properties of Eudragit S100 matrix pellets prepared by hot-melt extrusion.
abstract: Matrix-type pellets with controlled-release properties may be prepared by hot-melt extrusion applying a single-step, continuous process. However, the manufacture of gastric-resistant pellets is challenging due to the high glass transition temperature of most enteric polymers and an unacceptably high, diffusion-controlled drug release from the matrix during the acidic phase. The objective was to investigate the influence of three plasticizers (triethyl citrate, methylparaben and polyethylene glycol 8000) at two levels (10% or 20%) on the properties of hot-melt extruded Eudragit S100 matrix pellets. Extrusion experiments showed that all plasticizers produced similar reductions in polymer melt viscosity. Differential scanning calorimetry and powder X-ray diffraction demonstrated that the solid state plasticizers were present in the amorphous state. The drug release in acidic medium was influenced by the aqueous solubility of the plasticizer. Less than 10% drug was released after 2 h at pH 1.2 when triethyl citrate or methylparaben was used, independent of the plasticizer level. Drug release at pH 7.4 resulted from polymer dissolution and was not influenced by low levels of plasticizer, but increased significantly at the 20% level. Mechanical testing by diametral compression demonstrated the high tensile strength of the hot-melt extruded pellets that decreased when plasticizers were present.
authors.affiliation: Drug Dynamics Institute, College of Pharmacy, University of Texas at Austin, Austin, TX, USA.
authors.forename: Sandra U
authors.initials: SU
authors.lastname: Schilling
authors.forename: Hélène L
authors.initials: HL
authors.lastname: Lirola
authors.forename: Navnit H
authors.initials: NH
authors.lastname: Shah
authors.forename: A
authors.initials: A
authors.lastname: Waseem Malick
authors.forename: James W
authors.initials: JW
authors.lastname: McGinity
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D002951:Citrates / Q000737:chemistry; D003692:Delayed-Action Preparations / Q000737:chemistry*; D004339:Drug Compounding / Q000379:methods; D010226:Parabens / Q000737:chemistry; D010968:Plasticizers / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D013696:Temperature; D013718:Tensile Strength; D013806:Theophylline / Q000008:administration & dosage / Q000737:chemistry; D014783:Viscosity; D014961:X-Ray Diffraction
chemical_list: D000180:Acrylic Resins; D002951:Citrates; D003692:Delayed-Action Preparations; D010226:Parabens; D010968:Plasticizers; C050528:Eudragit RS; D011092:Polyethylene Glycols; C023001:ethyl citrate; C015358:methylparaben; D013806:Theophylline