Direct compression properties of melt-extruded isomalt.

Isomalt, a sugar alcohol, was melt-extruded prior to compression in order to improve its tabletting properties. After fusion, crystalline isomalt was transformed into an amorphous form as shown by X-ray diffraction and differential scanning calorimetry (DSC). The tabletting properties of amorphous isomalt were dramatically improved. Mixtures formulated with paracetamol (50%) and extruded isomalt yielded hard tablets. However, extruded isomalt powder showed agglomeration problems due to recrystallization of the amorphous phase into a stable crystalline form in the presence of atmospheric moisture. The evolution of the moisture content correlated well with the compressibility data. The tablets made of extruded isomalt powder had a lower friability in comparison to the tablets formulated with non-extruded isomalt powder. Their disintegration was fast and a rapid dissolution rate was recorded. Extruded isomalt displayed excellent tabletting properties; however, further experiments should be conducted to delay or even prevent recrystallization of amorphous isomalt.