Three commercially available microparticulate porous ceramics, N-light N3, Starlight SLK1000 and Carbolite 16/20, were characterised using a range of techniques. Starlight SLK1000 and Carbolite 16/20 were principally composed of mullite, while N-light N3 was principally composed of quartz. Each porous ceramic was partly open-cell with varying porosities and pore size distributions. Using a novel vacuum loading technique, N-light N3 was loaded with benzoic acid, sodium benzoate and diltiazem HCl, while Starlight SLK1000 and Carbolite 16/20 were loaded with diltiazem HCl. The drug loading was influenced by the solution concentration and by the porosity and bulk density of the ceramic. In vitro dissolution testing of the loaded porous microparticles showed an initial burst release of each drug followed by sustained release. The release was influenced by the surface pore size distribution of the ceramic and by electrostatic interactions between the interior and exterior microparticle surfaces and the drug.