Osmotic system for the controlled and delivery of agent over time

An osmotic system for the controlled and continuous delivery of a beneficial agent to the environment of use comprising:

• a. a shaped wall formed of a semipermeable material permeable to the passage of an external fluid in the environment of use and substantially impermeable to the passage of beneficial agent and compound, the shaped semipermeable wall surrounding and forming;
• b. a first and second compartment, said compartments separated by an expandable membrane permeable to fluid and substantially impermeable to beneficial agent and compound, and wherein the first compartment contains a beneficial agent in communication with the semipermeable wall and the second compartment contains an osmotically effective compound that exhibits an osmotic pressure gradient directly across the semipermeable wall against the fluid;
• c. a passageway in the semipermeable wall communicating with the beneficial agent compartment and the exterior of the system for delivering the beneficial agent from the system;
• and,
• d. wherein in operation, when the system is in the environment of use, fluid from the environment is imbibed through the semipermeable wall into (1) the first compartment containing the beneficial agent in a tendency towards osmotic equilibrium at a rate determined by the permeability of the wall and the osmotic pressure gradient across the wall, and into (2) the second comparment containing osmotically effective compound through the membrane at a rate determined by the permeability of the membrane and the osmotic pressure gradient across the membrane, said imbibitions increasing the volume of the second compartment and expanding the membrane into the compartment containing beneficial agent is delivered through the passageway from the system at a controlled rate over a prolonged period of time.

An osmotic system sized, shaped and adapted for placement in an environment of use, comprising:

• a. a shaped wall formed of a non-toxic semipermeable material permeable to the passage of fluid present in the environment of use and substantially impermeable to the passage of beneficial agent and osmotically effective agent;
• b. the semipermeable wall surrounding and forming a compartment housing a membrane that divides the compartment into an area containing beneficial agent in contact with the semipermeable wall and an area containing an osmotically effective agent in contact with the semipermeable wall;
• c. a passageway in the wall communicating with the area containing the beneficial agent for delivering said beneficial agent from the system;
• and,
• d. wherein in operation, when the system is in the environment, fluid is imbibed through the semipermeable wall into the areas in a tendency towards osmotic equilibrium at a rate determined by the permeability of the semipermeable wall and the osmotic pressure gradient across the semipermeable wall thereby delivering beneficial agent through the passageway from the system, with the amount of beneficial agent delivered from the system related to the volume of fluid imbibed into the area containing the beneficial agent and the volume of fluid imbibed into the area containing the osmotically effective agent over a prolonged period of time.