Besides the necessity of small-sized drug material, other draw- backs of the s/o/w technique might be the tendency of the drug to show sedimentation (higher density than suspension medium) or flotation (caused by adhesion of gas bubbles to the hydrophobic surface due to low wettability) during the encapsulation process and, in the later stages of the product development, difficulties can also be expected during scaling up to large-scale manufacture. Alterations, which might result from changes in the drug synthesis, e.g., in the drug crystal structure or the wetting behavior, are expected to affect the release profile from s/o/w particles. More- over, differences in the release might appear compared to dense microspheres that were prepared by the o/w technique and show a homogeneous drug distribution. Especially if comparatively large drug material is incorporated, the presence of sparsely encapsu- lated drug crystals at the microparticle surface can increase burst release (Birnbaum et al., 2000).