| 摘要 |
Device for controlled release of an active agent (I) comprises (I) dissolved in a non-swollen swellable hydrogel. The concn. of (I) increases from the surface of the device to its core, the conc. gradient being in the form of a continuous sigmoidal curve having a point of inflection. - The device is in the form of a bead with a dia. of O.01-20mm. (I) is a drug. The core of the bead is uniformly loaded with (I) and occupies 1-60% of the radius of the bead. The sigmoidal concn. gradient covers 30-99% of the radius, and the rest (up to 10% of the radius) is at least partially depleted of (I). The concn. of (I) at the surface is no more than 10% of its concn. in the core. The hydrogel is a water-insoluble water-swellable crosslinked polymer.
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