Delayed release drug formulation

A delayed release drug formulation for oral administration to deliver a 5-aminosalicylic acid (5ASA) to the intestine of a subject in need thereof, said formulation comprising:

• a core comprising said 5ASA;
• an isolation layer between said core and outer coating, and
• an outer coating surrounding the core for providing intestinal release of said drug, said outer coating comprising an outer layer and an inner layer,
• wherein said outer layer comprises a pH dependently soluble polymeric material which has a pH threshold at about pH 5 or above selected from the group consisting of polymethacrylate polymers, cellulose acetate phthalate, cellulase acetate trimelliate, hydroxypropyl methylcellulose phthalate, hydroxy propyl methylcellulose acetate succinate and polyvinyl acetate phthalate, optionally in admixture with a digestible polymeric material which is susceptible to attack by colonic bacteria, said polymeric material being present in a total coating amount from about 2 mg/cm2 to about 10 mg/cm2 based on the dry weight of the total polymeric material, wherein said isolation layer comprises at least one non-ionic polymer, wherein a composition of said isolation layer and a composition of said inner layer are different, and
• wherein the inner layer comprises (i) a soluble non-ionic polymer which is soluble in gastrointestinal fluid selected from the group consisting of methylcellulose;
• hydroxypropyl cellulose (HPC);
• hydroxypropyl methylcellulose (HPMC);
• poly(ethylene oxide)-graft-polyvinyl alcohol;
• poly vinylpyrrolidone (PVP);
• and polyvinyl alcohol (PVA), said soluble non-ionic polymer being present in the inner layer an amount from about 2 mg/cm2 to about 10 mg/cm2 based on the dry weight of the polymer, (ii) a buffer agent selected from the group consisting of a carboxylic acid having from 1 to 16 carbon atoms, an alkali metal salt, an alkali earth metal salt, an ammonium salt and a soluble metal salt, said buffer agent being present in the inner layer in a total amount form about 10 wt % to about 30 wt % based on the dry weight of the soluble non-ionic polymer of the inner layer, and (iii) a base is selected from the group consisting of hydroxide bases, alkali metal bicarbonates, alkali metal carbonates, alkali metal phosphates, alkali metal citrates, or physiologically tolerated amines.