This invention relates to sustained-release, solid-dosage forms having non-uniform distribution of active ingredient which provides for zero-order release of the active ingredient. The non-uniform distribution Is accomplished by providing for a multitude of enveloping, concentric layers over a central core. Each of the various layers having constant concentration of a hydrophilic gel and each layer and the core having an amount of medicament defined by the expressionwherein DL is the amount of medicament in the core or in any given sustained-release layer, DT is the total amount of medicament in the sustained-release portion of the tablet, RD is the differential radius for the core or the enveloping layer for which the amount of required medicament is to be determined and RT is the radius of the sustained-release portion of the tablet.
本发明涉及具有活性成分非均匀分布的缓释固体剂型,可实现活性成分的零阶释放。非均匀分布是通过在中央核心上设置多个同心层来实现的。各层中的每一层都具有恒定浓度的亲
水性凝胶,每一层和片芯中的药量由以下表达式确定:DL 是片芯或任何给定缓释层中的药量,DT 是片剂缓释部分的药量,RD 是片芯或包膜层的差分半径,其中所需药量由该半径确定,RT 是片剂缓释部分的半径。