Liquid prolonged release pharmaceutical formulations containing ionic constituents

Claim 1

A formulation of an ionic drug wherein the drug is present as a component of a coated drug-resin complex suspended in a liquid carrier which carrier also contains a second ionic component bearing the same charge as the coated complexed drug, the second ionic component being present as a component of an uncoated resin complex, the resin particle of the coated drug-resin complex being an ion exchange resin having been treated in an amount sufficient to retard its rate of swelling in water with an impregnating agent selected from the group consisting of polyethylene glycol, propylene glycol, mannitol, lactose and methylcellulose, and which treated particle has been subsequently coated with a water-permeable diffusion barrier, the second ionic component being present in an amount that would disturb the dissolution profile of the coated drug-resin complex if that amount was present in unbound form instead of as a component of an uncoated resin complex, and the resin of the uncoated resin particle being an ion exchange resin present in an amount that is sufficient to bind the second ionic component but is not so large as to disturb the dissolution profile of the coated drug-resin complex.