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制备一种每天释放左炔诺孕酮Levonorgestrel(LNG)2μg的宫内节育器(IUD),并对之进行体外释药速度的研究。本IUD选用乙烯醋酸-乙烯共聚物(EVA)材料,T型纵臂为贮药管,内装LNG、硫酸钡及硅油所组成的混悬剂,EVA管壁为释药限速膜。本释药系统在“漏槽”状态下测定其稳态释药速度,表明在长时期内可维持零级速度。释药速度是管壁厚度及(或)药管内外径比的线性函数,说明本系统属于骨架控制释放机理。温度与标化速度关系符合Arrhenius方程,可以估算温度每升高1℃,本系统释药速度增加约16％。
An intrauterine device (IUD), which releases 2 μg levonorgestrel (LNG) per day, was prepared and studied for its in vitro release rate. The IUD is made of ethylene-vinyl acetate (EVA) material. The T-shaped longitudinal arm is a storage tube filled with a suspending agent composed of LNG, barium sulfate and silicone oil. The wall of the EVA tube is a drug release rate limiting membrane. The drug delivery system determines the steady-state drug release rate in the “drain” state, indicating that the zero-speed can be maintained over a long period of time. The drug release rate is a linear function of the thickness of the tube wall and / or the OD of the tube, indicating that the system belongs to the mechanism of controlled release of the skeleton. The relationship between temperature and the standardization rate is in accordance with the Arrhenius equation. It can be estimated that for every 1 ° C increase in temperature, the release rate of the system is increased by about 16%.