| 摘要 |
Disclosed are dispensing systems for releasing a substance at a substantially constant rate and methods for its manufacture. The composition comprises semipermeable capsules containing the material to be released. The capsules comprise membranes having pores of dimensions sufficient to control the kinetics of release provided there is maintained a large intracapsular concentration of the substance relative to the concentration desired in the extracapsular environment. The compositions may be produced by forming permeable capsules, suspending the capsules in a solution containing a high concentration of the substance to load the intracapsular volume, and then post-treating the capsules to reduce the size of the pores.
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