Method for the preparation of a pharmaceutical composition comprising 5-aminosalicylic acid for use in treatment of ulcerative colitis and Crohn's disease

A method for the preparation of prolonged-release tablets of 5-aminosalicyclic acid (5-ASA) or pharmaceutically acceptable salt or ester thereof, comprising:

• (a) mixing polyvinyl pyrrolidone as a pharmaceutically acceptable binder in a solvent;
• the solvent consisting of at least 85% w/w water and up to 15% w/w organic solvent;
• (b) mixing the solvent-binder mixture with 5-ASA to form a wet mass consisting of 5-ASA, binder, and solvent, in which the solvent is present at up to 35% by weight of the weight of 5-ASA;
• (c) extruding the wet mass to form strong, smooth granules comprising 5-ASA and binder;
• (d) drying the granules in a continuous fluid bed dryer to produce dried granules in which:
• the weight ratio of the pharmaceutically acceptable binder to 5-ASA is up to 6.5:100;
• and
• more than 85% of the dried granules have a particle size of 850 to 1000 μm;
• (e) coating the dried granules with a solution of a pharmaceutically acceptable coating material in a coating organic solvent, wherein the amount of the coating composition is adjusted to the specific surface area of the dried granules to achieve the desired dissolution rate profile;
• (f) purging coating organic solvent from the coated granules;
• (g) mixing the coated granules with one or more pharmaceutically acceptable tablet excipients;
• and
• (h) forming tablets from the resulting mixture.