The described agglomeration of drug microparticles blended with excipient microparticles is a technique for the size enlargement of micronized products that could be damaged by granulation or compaction techniques. These agglomerates can be used as oral prompt or delayed-release dosage forms administered as they are or dispersed in a liquid. The composition and quantity of the excipient microparticles resulted to be the crucial factors for the agglomerate quality. Therefore, adjusting the content of surface-active agent between 8-20% of the excipient microparticles, it is possible to agglomerate microparticles of drugs that could not be agglomerated per se. Increasing the surfactant concentration in the spray-dried excipient microparticles or increasing the fraction of these excipient microparticles in the blend, the agglomeration was improved. The spray drying technique concentrates the surface-active agent on the microparticle surface. By tumbling, the surface-active agent present on microparticles excipient surface was spread to fill the inter-particle interstices of drug particles giving rise to more resistant agglomerates. This phenomenon occured also by vibration; the production in thi case was quicker.