title: Development and physicochemical characterization of sirolimus solid dispersions prepared by solvent evaporation method.
abstract: OBJECTIVE
  The aim of the present investigation was preparation and characterization of sirolimus solid dispersions by solvent evaporation technique to improve its dissolution properties.
  
  
  METHODS
  Polyvinylpyrrolidone (PVP), Poloxamer 188 and Cremophore RH40 were used to prepare the solid dispersions of sirolimus. In vitro dissolution study using USP type I apparatus, were performed in distilled water (containing SLS 0.4%) for pure sirolimus, physical mixtures, Rapamune and prepared solid dispersions. The characterization of solid dispersions was performed using Fourier Transform Infrared (FTIR) Spectroscopy and Differential Scanning Calorimetry (DSC).
  
  
  RESULTS
  More than 75% of sirolimus was released within 30 minutes from all prepared solid dispersions. The dissolution rate of all prepared solid dispersion powders were more than physical mixtures. The absence of sirolimus peak in the DSC spectrum of solid dispersions indicated the conversion of crystalline form of sirolimus into amorphous form. The results from FT-IR spectroscopy showed that there was no significant change in the FT-IR spectrum of solid dispersions indicating absence of well-defined interaction between drug and carriers.
  
  
  CONCLUSIONS
  It was concluded that solid dispersion method, using PVP, Poloxamer 188 and Cremophore RH40 can improve dissolution rate of sirolimus.
authors.affiliation: Students' Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Shahram
authors.initials: S
authors.lastname: Emami
authors.affiliation: Drug Applied Research Center and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Hadi
authors.initials: H
authors.lastname: Valizadeh
authors.affiliation: Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. ; Faculty of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran.
authors.forename: Ziba
authors.initials: Z
authors.lastname: Islambulchilar
authors.affiliation: Liver and Gastrointestinal Diseases Research Center and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Parvin
authors.initials: P
authors.lastname: Zakeri-Milani
keywords: Dissolution enhancement; Immunosuppressive; Poor soluble; Rapamycin