title: Experimental Design to Predict Process Variables in the Microcrystals of Celecoxib for Dissolution Rate Enhancement Using Response Surface Methodology.
abstract: OBJECTIVE
  The purpose of the present investigation was to increase the solubility and dissolution rate of celecoxib (CLX) by preparing microcrystals of drug by solvent change precipitation.
  
  
  METHODS
  This procedure was optimized in order to obtain stable and homogeneous particles with a small particle size, high yield and fast dissolution rate. CLX agglomerates were prepared with brij35 (stabilizer agent) using acetone as solvent, water as non-solvent, respectively. The agglomerates were characterized by DSC, XRD, FTIR studies. A full-factorial design was employed to study the effect of independent variables, the amounts of stirring rate (X1), volume of organic solvent (X2), volume of aqueous solvent (X3), time of stirring (X4), concentration of Brij (X5), concentration of Tween 80 (X6), concentration of HPMC (X7) on dependent variables, particle size (PS), drug content (DC), drug released after 15 min (Q15), crystal yield (CY), Gibbs free energy change (ΔG°tr), antalpy change (ΔH) and saturated solubility (Ss).
  
  
  RESULTS
  The DSC and FTIR results indicated the absence of any interactions between drug and stabilizers. These studies showed a decrease in crystalinity in agglomerates. The crystals exhibited significantly improved micromeritic properties compared to pure drug. The drug content and crystal yield were in the range of 32.84-48.22% and 64.55-83.33% with all formulations, respectively. The solubility and drug release rates increased with an increase in concentration of stabilizer.
  
  
  CONCLUSIONS
  The results show that microcrystals of the drug in stabilizer considerably enhanced the dissolution rate.
authors.affiliation: Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. ; Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Mitra
authors.initials: M
authors.lastname: Jelvehgari
authors.affiliation: Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. ; Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Hadi
authors.initials: H
authors.lastname: Valizadeh
authors.affiliation: Islamic Azad University of Bonab Unit, Bonab, Iran.
authors.forename: Seyed Hassan
authors.initials: SH
authors.lastname: Montazam
authors.affiliation: Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. ; Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Sanam
authors.initials: S
authors.lastname: Abbaszadeh
keywords: Brij 35; Celecoxib; Dissolution; Microcrystal; Release