Delayed release of a drug to the colon is achieved from a delayed release formulation comprising a core and a coating for the core. The core comprises a drug and the coating comprises an inner layer and an outer layer. The outer layer comprises a mixture of a first polymeric material which is susceptible to attack by colonic bacteria, and a second polymeric material which has a pH threshold at about pH 6 or above. The inner layer comprises a nonionic polymer as a third polymeric material which is soluble in intestinal fluid or gastrointestinal fluid, and at least one of a buffer agent and a base. Advantages of formulations according to the present invention include accelerated release of the drug when exposed to colonic conditions and reduction or elimination of a food and/or alcohol effect on drug release after administration.
