Modified release formulations containing drug-ion exchange resin complexes

An orally ingestable, modified release, composition comprising:

• (i) a particulate drug-ion exchange resin matrix, said drug-ion exchange resin complex comprising a pharmaceutically acceptable, orally ingested drug, bound to a pharmaceutically acceptable water insoluble ion exchange resin to form a drug-ion exchange resin complex, said ion exchange resin being selected from a copolymer comprising styrene with divinylbenzene and a copolymer comprising methacrylic acid with divinylbenzene,
• wherein said drug-ion exchange resin complex is further in a matrix comprising said drug-ion exchange resin complex and a drug release retardant, wherein said release retardant is present in an amount of about 3% to about 30% by weight, based on the weight of said drug-ion exchange resin complex defined in (i), and said drug release retardant comprises a water insoluble polymer or copolymer or a hydrophilic polymer, said drug-ion exchange resin matrix comprising particles of a size capable of passing through a number 40 mesh COMIL screen, and
• (ii) a cured, high tensile strength, water permeable, water insoluble, non-ionic polymeric diffusion barrier coating over said particulate drug-ion exchange resin matrix defined in (i), said coating applied as an aqueous dispersion, said aqueous based coating dispersion comprising a polyvinylacetate polymer with a stabilizer, and wherein said cured coating further includes an effective amount of plasticizer in said cured, high tensile strength, water permeable, water insoluble, non-ionic polymeric diffusion barrier coating, whereby said cured coating provides a modified release profile to the drug in said drug-ion exchange resin matrix.