Abstract: The present invention pertains to controlled release tacrine drug delivery systems comprising an immediate release composition and a sustained release composition wherein (1) the immediate release composition comprises in percentages by weight of the immediate release composition: (A) immediate release pellets comprising: (a) nonpareil seeds in an amount from about 25% to about 75%; (b) tacrine in an amount from about 10% to about 80%; and (c) a binding agent in an amount from about 1% to about 10%; and (B) a sealing layer over the immediate release pellets comprising: (a) a sealing agent in an amount up to about 6%, and (b) a first plasticizing agent in an amount up to about 5%; and (2) the sustained release composition comprises in percentages by weight of the sustained release composition; (A) the immediate release composition; and (B) a sustaining layer over the immediate release composition comprising; (a) a water-insoluble polymer in an amount from about 40% to about 90%; (b) a water-soluble polymer in

Abstract: Semi-enteric controlled release formulations are comprised of a biological active agent such as an antibiotic that is blended with a water-soluble bulking agent, the mix then coated onto an inert core. The coated active core is further coated with a mixture comprised of an acrylic copolymer, bulking agent and pH dependent food acid. These different coating components possess different solubility characteristics which result in a gradual release of the active in both the stomach and small intestine that provides an increased bioavailability of the active drug.