title: Preparation and characterization of solid dispersion of simvastatin.
abstract: BACKGROUND
  Simvastatin (SIM), a widely used drug for the treatment of hypercholesterolemia, is a crystalline substance and practically insoluble in water. Its low dissolution rate leads to a poor absorption, distribution, and target organ delivery because the bioavailability of drugs with low aqueous solubility is limited by their dissolution rates.
  
  
  OBJECTIVE
  The aim of this study was to prepare solid dispersions (SD) of SIM with inert carriers in an attempt to improve the release profile.
  
  
  METHODS
  In this work, SIM SD with polyethylene glycol (PEG 6000) or polyvinylpyrrolidone (PVP K15) in 1:1, 1:2, 1: 3, 1:4, and 1:5 ratios were prepared and their stability and dissolution properties were investigated. SD were characterized by differential scanning calorimetry and X-ray powder diffraction. Tablets containing SD SIM : PEG 6000 were developed and their dissolution profile evaluated.
  
  
  RESULTS
  Drug release from all SD was significantly improved when compared to their corresponding physical mixture or SIM alone. SD SIM:PVP showed drug degradation. The tablets gradually released SIM with a final quantity greater than 80% in 60 minutes.
  
  
  CONCLUSIONS
  The preparation of SIM SD with PEG or PVP is a promising strategy to improve the bioavailability of the drug. SIM SD with PEG are more advantageous over the dispersions prepared with PVP because they do not show drug degradation during preparation.
authors.affiliation: Department of Pharmaceutical Products, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Taízia D
authors.initials: TD
authors.lastname: Silva
authors.forename: Valquíria T
authors.initials: VT
authors.lastname: Arantes
authors.forename: Jackson A L C
authors.initials: JA
authors.lastname: Resende
authors.forename: Nivaldo L
authors.initials: NL
authors.lastname: Speziali
authors.forename: Renata B
authors.initials: RB
authors.lastname: de Oliveira
authors.forename: Cristina D
authors.initials: CD
authors.lastname: Vianna-Soares
mesh_terms: D001682:Biological Availability; D002152:Calorimetry, Differential Scanning; D004337:Drug Carriers / Q000737:chemistry*; D004355:Drug Stability; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000008:administration & dosage* / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011205:Povidone / Q000737:chemistry; D019821:Simvastatin / Q000008:administration & dosage* / Q000737:chemistry; D012995:Solubility; D013607:Tablets; D014961:X-Ray Diffraction
chemical_list: D004337:Drug Carriers; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D013607:Tablets; D011092:Polyethylene Glycols; D019821:Simvastatin; D011205:Povidone