Abstract: Unit dosage form for delivering drugs into the body in a series of sequential, pulsatle releasing events employs conventional pharmaceutical equipment and processes for optimum economy, reliability, and bioavailability. The system can be used with drugs which cannot be released by diffusion through a porous coating, such as water insoluble drugs. A plurality of populations of pellets is provided within a unit dosage form such as a capsule or tablet. The pellets are composed of a core containing the drug and a swelling agent which expands in volume when exposed to water. The core is enclosed within a membrane or coating which is permeable to water. The membrane is composed of a water insoluble and permeable film forming polymer, a water soluble film forming polymer and a permeability reducing agent. When the unit dose releases the pellets into the digestive tract, water diffuses through the coating and into the core.

Abstract: A unit dosage form of capsule, tablet or the like is composed of a large number of pellets made up of two or more populations of pellets or particles. Each pellet contains a core containing the therapeutic drug and a water soluble osmotic agent. A water-permeable, water-insoluble polymer film encloses each core. In corporated into the polymer film is a hydrophobic, water insoluble agent which alters the permeability of the polymer film. The film coating of each population of pellets differs from the coating of every other population of pellets in the dosage form in the rate at which water passes through to the core and the rate at which drug diffuses out of the core. The osmotic agent dissolves in the water, causing the pellet to swell and regulating the rate of diffusion of drug into the environment of use. As each population of pellets releases its drug into the environment sequentially, the effect is to provide a series of pulsatile administrations of the drug from a single dosage form.