Effect of protective colloids on the induction of polymorphic changes in indomethacin agglomerates after solvent evaporation from o/w emulsions

Indomethacin (IMC) agglomerates were prepared by the solvent evaporation pr ocess from ow emulsions containing different protective colloids in the ext ernal aqueous solution. The types of protective colloids inducing the polym orphic transformation of IMC in the agglomerates without wall material were investigated. The composition and its polymorphs were evaluated from the X -ray diffraction patterns, IR spectra and DSC thermograms. The results indi cate that when pectin, P-cyclodextrin, sodium alginate or sodium dodecyl su pphase acted as a protective colloid, the respective IMC agglomerates consi sted only of the a form of IMC. When gelatin or hydroxypropyl methylcellulo se was used as a protective colloid, the amorphous, a and gamma forms as we ll as methylene chloride solvates of lMC were found in the IMC agglomerates . There was only methylene chloride solvate of IMC with a small amount of a morphous form in the IMC agglomerates prepared from albumin as a protective colloid, while IMC agglomerates prepared from methylcellulose, polyvinyl a lcohol or biosoluble polymer consisted of the mixture of amorphous and alph a forms, and methylene chloride solvate of IMC. When polyvinyl pyrrolidone was applied to act as a protective colloid, the mixture of methylene chlori de solvate and gamma form of IMC with less quantity of amorphous form was f ound in its IMC agglomerates. This strongly suggests that the composition o f IMC agglomerates prepared from the solvent evaporation process was signif icantly influenced by the type of protective colloids used.