| abstract |
An osmotic device for delivering an active agent is disclosed. The device is comprised of a wall surrounding a compartment and has a passageway through the wall for dispensing the agent. The wall is formed of a material permeable to an external fluid and substantially impermeable to agent and a gas generating means. The compartment is comprised of an active agent and a gas generating means that either exhibits an osmotic pressure gradient against the external fluid, or the means is mixed with an osmotically effective compound that exhibits an osmotic pressure gradient against the fluid. Agent is released by fluid being imbibed through the wall into the compartment at a rate controlled by the permeability of the wall and the osmotic pressure gradient across the wall, which fluid wets the means causing it to react and produce an effervescent solution containing agent that is dispensed under pressure through the passageway to the exterior of the device. |