| abstract |
An osmotic system for delivering a beneficial agent to an environment of use is disclosed. The system comprises a laminate surrounding a compartment and has a passageway through the laminate for releasing agent from the compartment. The laminate comprises at least two laminae; one consisting of a semipermeable, polymeric material that is permeable to the passage of an external fluid and maintains its physical and chemical integrity in the environment of use, and one consisting of a semipermeable polymeric material that is permeable to the passage of fluid, substantially impermeable to the passage of agent and maintains its physical and chemical integrity in the presence of agent. The compartment comprises an active agent that is either soluble in the external fluid and exhibits an osmotic pressure gradient across the laminate against the fluid, or the agent has limited solubility in the fluid and it is mixed with an osmotically effective compound that is soluble in the fluid and exhibits an osmotic pressure gradient across the laminate against the fluid. In operation, agent is released from the system by fluid being imbibed through the laminate into the compartment at a rate controlled by the permeability of the laminate and the osmotic pressure gradient across the laminate producing a solution containing agent, or a solution of compound containing agent which solution in either operation is released through the passageway at a controlled and continuous rate over a prolonged period of time. |