PhysChemForum edition:4 location:UCB, Brussels, Belgium date:30 November 2007
Purpose. To compare thermal characteristics and dissolution properties of solid dispersions prepared via two solvent methods: spray drying and film casting.
Methods. Binary dispersions of itraconazole and polymers like PVP-VA 64, PVP K25, HPMC 2910 5 mPa.s, PEG 6000, Eudragit E 100 and Poloxamer 407 were prepared by spray drying (Büchi Mini Spray Dryer B-191), or via film casting. Process factors investigated were the ratio itraconazole/polymer, solvent ratio and temperature. MDSC was used to characterise powders and crushed films. Dissolution properties were examined in 500ml SGF (37°C; 100RPM) using the paddle method and HPLC with UV-detection.
Results. Binary dispersions of itraconazole and PVP-VA 64, PVP K25 or HPMC are molecular dispersions. HPMC dispersions containing 40% or more of itraconazole showed a crystalline drug phase. MDSC shows no difference between the two manufacturing methods; dissolution profiles however are very different: itraconazole dissolves faster and better from films. Dispersions with Eudragit E100 appear as a glass solution but a separate amorphous drug phase can be detected if the drug concentration is 40% or higher. DSC curves and dissolution profiles for both methods of dispersion preparation are identical. Itraconazole is present as a separate crystalline phase in PEG 6000 and poloxamer 407 dispersions at higher drug concentrations. Thermograms are identical for both methods of preparation. Drug dissolution from PEG 6000 dispersions is higher from dispersions prepared by spray drying.
Conclusions. Dispersions prepared via film casting or spray drying generate the same result with respect to their thermal characteristics, but not in terms of dissolution properties.