Indobufen pellets, previously prepared by direct pelletization employing the rotary tangential spray fluidized bed (Rotoprocessor), were coated using the same equipment setup as for the film coating process. Different amounts of the aqueous-based ethylcellulose dispersion (Aquacoat) were easily applied on the active cores of different compositions with no spray blocking or pellet sticking. The coating process was not influenced by changing the ethylcellulose (Aquacoat ECD-30) formulation with soft acrylic resin (Eudragit NE 30D) or by adding water-soluble polymers (Pharmacoat 606 and PEG 6000) to the coating dispersions. Simple setup, flexibility of operation, and short manufacturing times were the advantageous features of the tangential spray equipment. These benefits were verified during the pellet coating process. The composition of the cores and membranes were confirmed as the determining parameters with respect to the performances in terms of the drug release rate. The morphological and functional results clearly demonstrated the tangential spray rotary system as a promising one-step technique for the preparation of indobufen prolonged-release multiple-unit dosage forms.