Optimisation and scale-up of a highly-loaded 5-ASA multi-particulate dosage form using a factorial approach

Pellets with high loading of 5-aminosalicylic acid (5-ASA, mesalamine) are desired to reduce the number of tablets required to deliver the daily dosing regimen. Recently, we reported an extrusion-spheronisation route for the development of a 90 wt% 5-ASA/microcrystalline cellulose formulation based on milled 5-ASA which gave good yields of pellets at the lab scale. In the present work, such formulation was optimised further by preliminary studies using a lab-scale ram extruder, and then scaled up to the pilot plant scale on a Nica screen extruder using a mixed fractional factorial approach. The final formulation featured 95 wt% 5-ASA and 5 wt% Avicel RC591 (all dry basis) and yielded spherical pellets suitable for use as the drug core of a multi-particulate DDS.