The present invention is directed to the oral osmotic delivery of therapeutic compounds that have limited solubility in an aqueous environment due to inherent hydrophobicity or to saturation limitations in the core of the osmotic system. The present invention is suitable for the osmotic delivery of glipizide and other hydrophobic drugs, but runs the spectrum to other therapeutic agents with higher aqueous solubilities, yet having a solubility limitation in an osmotic dosage unit due to high drug load.