The goal was to make available a delayed-release dosage form of mesalazine to be dispersed in water to facilitate swallowing in adults and children. Mesalazine microparticles containing carnauba wax were prepared by spray-congealing technique. A second step of spray-congealing of carnauba microparticles dispersed in liquefied stearic acid gave rise to mesalazine lipid microcapsules in which several carnauba microparticles remained embedded as cores in a reservoir structure. In order to favor their water dispersion, the lipid microcapsules were dry coated by tumbling them with different ratios of mannitol/lecithin microparticles prepared by spray-drying.
Release rate measurements showed a delayed-release behavior, in particular a pH-dependence with less than 10% of drug released in acidic medium and complete release in phosphate buffer pH 7.4 in 4–5 h. The layering with hydrophilic excipient microparticles allowed manufacturing of a pH-dependent dosage form suitable for extemporaneous oral use in adults and children.