Microencapsulation of an iron chelator for sustained release and crystal habit modification

DMHP (1,2-dimethyl-3-hydroxy-pyrid-4-one) is an orally-active iron chelator that has a short biological half-life and hence a sustained-release formulation is currently being developed. DMHP exists as needle-like crystals that cannot be size-characterized accurately for pharmaceutical manufacturing. The current study was undertaken to simultaneously achieve crystal-habit modification and provide sustained-release properties using a microencapsulation technique. Eudragit-RS, -RL, -L90 and Cellulose Acetate Phthalate were used in a phase-separation method to produce discrete, spheroidal, free flowing microcapsules of DMHP that could be sized readily. The obtained microcapsules were evaluated for drug content, size distribution, micromeritic properties, and in-vitro dissolution in gastric followed by intestinal pH environments at 37 degrees C. In-vitro dissolution studies revealed that DMHP release from the microcapsules can be retarded for up to 10 h. Changes in polymer type, polymer content, and processing parameters resulted in drastic changes in the microencapsulation process, and release characteristics of the microcapsules.