Osmotic membrane and delivery device

摘要

The present invention relates to an improvement in an osmotic delivery device wherein the device comprises a semipermeable wall comprising cellulose acetate butyrate and surrounding an internal compartment containing a beneficial agent or medicament formulation, a fluid-activated expandable driving member, optionally a partition layer between the agent formulation and the driving member, and, optionally a density member, and exit means in the semipermeable wall; and wherein the improvement comprises the cellulose acetate butyrate component of the semipermeable wall having a differential scanning calorimetry ("DSC") profile wherein the main or primary DSC peak has a minimum temperature peak above 228 DEG C. and the secondary DSC peak area is equal to or less than about 30% of the total combined areas of the primary and secondary DSC peaks. The invention also relates to the improved semipermeable membrane produced from cellulose acetate butyrate having a differential scanning calorimetry ("DSC") profile wherein the main DSC peak is at a temperature above 228 DEG C. and the secondary DSC peak area is equal to or less than about 30% of the total combined area of the primary and secondary DSC peaks, the semipermeable membrane providing a substantially improved uniform rapid startup performance for osmotic delivery devices.