Influence of polyethylene glycol 4000 on the polymorphic forms of diflunisal.
The present study was carried out to investigate the physico-chemical characteristics of diflunisal-PEG 4000 solid dispersions prepared by melting, solvent and melting-solvent methods. The solvents chosen were chloroform, methanol and ethanol-water due to the fact that the drug presents different polymorphic forms in these solvents. The characterization of solid dispersions was performed by X-ray powder diffraction because this technique has the advantage over other identification methods that it can detect both drug and ligand simultaneously. The X-ray diffraction patterns of the diflunisal-PEG systems suggested that the drug/polymer ratio and the solvent nature play an important role in the crystallization of the drug. In this regard, diflunisal crystallizes in form I at high concentrations of the drug (drug/polymer 2:1) in the solidified melt dispersions, however, polymorph III is mainly obtained as the polymer content increases (1:1 and 2:3). Likewise, in solid systems obtained by the solvent and melting solvent methods the drug solidifies in form III in ethanol/water and methanol while polymorph IV crystallizes in chloroform. Finally, DSC thermograms and hot-stage microscopy data of solid dispersions prepared by the melting method have allowed to draw the diflunisal-PEG 4000 solid-liquid phase diagram.
Martínez-Ohárriz
M C
MC
Departamento de Química (Sección de Química Física), Facultad de Ciencias, Edifico de Investigation, Universidad de Navarra, 31080, Pamplona, Spain. moharriz@unav.es
Martín
C
C
Goñi
M M
MM
Rodríguez-Espinosa
C
C
Tros-Ilarduya
M C
MC
Zornoza
A
A
D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D004061:Diflunisal / Q000737:chemistry*; D005079:Excipients; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers; D012995:Solubility; D012997:Solvents; D014961:X-Ray Diffraction
D005079:Excipients; D011108:Polymers; D012997:Solvents; D011092:Polyethylene Glycols; D004061:Diflunisal