Abstract

A method is disclosed for delivering a drug substantially-free of rapid precipitation from an osmotic device. The osmotic device comprises a semipermeable wall surrounding a compartment housing (1) a drug that exhibits limited solubility under neutral and acid conditions, and (2) a compound capable of evolving carbon dioxide in the presence of an acid in the environment of use. The method comprises, (a) imbibing fluid through the wall into the compartment at a rate determined by the permeability of the wall and the osmotic pressure gradient across the wall, (b) forming in the compartment a basic solution containing drug and compound, which solution is delivered from the compartment through the passageway, (c) reacting the compound with the acid in the environment at the device-environment interface for evolving carbon dioxide, thereby, (d) providing an effervescent suspension in the environment that delivers the drug in a finely dispersed form to the environment of use over time. Also, a composition is disclosed comprising the drug and the compound.