The aim of the present study was to develop a fast-dissolving solid dosage form containing theophylline as active ingredient using the freeze-casting technique. The structure, the physical properties and mechanism of drug release from the freeze-casted units were investigated. The examined properties of the samples were compared with those of tablets compressed by an eccentric tableting machine using three different compression pressures. The freeze-casting technique proved to be an appropriate alternative for the development of porous solid drug delivery systems. The mechanical strength of the matrices could be improved by using water-soluble additives, which stabilized the solid bodies during recrystallization upon drying. As compared with the tablets, the freeze-casted units revealed a highly porous nature and a remarkable difference in pore volume size distribution. The results demonstrated that the drug-solvent interaction, enhanced by the structural properties, resulted in a rapid delivery of the theophylline from the solid units into artificial gastric juice. (c) 2006 Elsevier B.V. All rights reserved.