RELATIONSHIP BETWEEN RELEASE RATE AND SURFACE CONCENTRATION FOR HEPARINIZED MATERIALS
RELATIONSHIP BETWEEN RELEASE RATE AND SURFACE CONCENTRATION FOR HEPARINIZED MATERIALS
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DOI：
10.1002/jbm.820170310
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发表时间：
1983-01-01
期刊：
影响因子：
--
通讯作者：
SEFTON, MV
中科院分区：
文献类型：
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作者：
BASMADJIAN, D;SEFTON, MV
数学模型用于预测肝素释放到流动血液和停滞或充分混合的血浆中所产生的表面浓度。两种释放率. sbd.4x. 10-2和3倍。10-5μ g/cm 2 min.sbd，其分别描述了从离子肝素化材料和从固定化肝素-PVA（聚乙烯醇）水凝胶的洗脱。当肝素以较高速率释放到在具有脉管系统特征尺寸的圆柱形管或代表导管实验的环形管中流动的血液中时，实际上在管入口处获得0.5 μ g/ml的最小表面浓度。以较低速率释放需要数千米的管长度以达到相同的临界值。类似地，以较高速率从珠粒悬浮液释放的肝素导致在停滞血浆中在几分之一秒内的0.2 μ g/ml的临界表面浓度，或5、在一个和谐的环境中在较低的释放速率下，必须经过45或100分钟才能达到相同的水平。这些结果支持了4 × 10 - 4的有效性。10-2μ g/cm 2 min作为合理的最小释放速率，以产生足以防止血栓形成的肝素微环境。较低的速率不足以产生临界浓度，因此支持肝素-PVA的生物活性不归因于肝素微环境的论点。该模型方程可以应用于任何材料的释放，以确定表面浓度。
Mathematical models are used to predict surface concentrations that result from the release of heparin into flowing blood and stagnant or well-mixed plasma. Two release rates.sbd.4 .times. 10-2 and 3 .times. 10-5 .mu.g/cm2 min.sbd.are considered, which describe elution from an ionically heparinized material and from an immobilized heparin-PVA(polyvinyl alcohol) hydrogel, respectively. When heparin is released at the higher rate into blood flowing in cylindrical tubes with dimensions characteristic of the vasculature, or annular tubes representative of catheter experiments, a minimum surface concentration of 0.5 .mu.g/ml is attained virtually at the tube inlet. Release at the lower rate requires tube lengths of several thousand meters to attain the same critical value. Similarly, heparin released from a suspension of beads at the higher rate leads to critical surface concentrations of 0.2 .mu.g/ml within a fraction of a second in stagnant plasma, or .apprx. 5 s in a well-mixed environment. At the lower release rate, 45 or 100 min must elapse before the same level is achieved. These results support the validity of 4 .times. 10-2 .mu.g/cm2 min as a reasonable minimum release rate to produce a heparin microenvironment sufficient to prevent thrombosis. The lower rate is shown to be insufficient to generate a critical concentration, thus supporting the argument that heparin-PVA does not owe its biological activity to a heparin microenvironment. The model equations can be applied to the release of any material to determine surface concentrations.