Otto H. York Department of Chemical, Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA.
Curr Drug Deliv. 2011 Mar;8(2):144-51. doi: 10.2174/156720111794479916.
Analytical expressions were derived to explain the influence of the dissolution/diffusion number (Di) on the time constant and steady-state flux when dispersed drugs are released from a finite matrix. A key novelty of this work is the introduction of a single time-constant that combined the analysis of both dissolution- and diffusion-based systems. Focus is placed on systems with a constant dissolution rate and diffusion coefficient. Solutions, based on the residue theorem, were in agreement with published results describing the transport of estradiol in a polymeric matrix. The experimental cumulative amount of drug released was 0.1 mg/cm² in 100 hours compared to 0.084 mg/cm² predicted by the theoretical model. The process time constant, estimated from the first eigenvalue (t0) and a more accurate statistical approach (t(eff)), showed a consistent decrease with increasing Di values. For a dissolution/diffusion number of 0.21, t0 and t(eff) were estimated at 58.44 and 73.02 hrs, respectively. With the presence of a skin layer, t(eff) increased to 575.7 hrs. These results can be used to assess the relative impact of dissolution and diffusion on the time it takes drugs to attain a therapeutic level in the bloodstream.
解析表达式被推导出来，以解释在分散药物从有限基质中释放时，溶解/扩散数（Di）对时间常数和稳态通量的影响。这项工作的一个主要新颖之处在于引入了一个单一的时间常数，将溶解和扩散系统的分析结合在一起。重点放在具有恒定溶解速率和扩散系数的系统上。基于残数定理的解与描述雌二醇在聚合物基质中传输的已发表结果一致。在 100 小时内，实验释放的累积药物量为 0.1mg/cm²，而理论模型预测为 0.084mg/cm²。从第一个特征值（t0）和更准确的统计方法（t（eff））估计的过程时间常数随着 Di 值的增加而持续下降。对于溶解/扩散数为 0.21，t0 和 t（eff）分别估计为 58.44 和 73.02 小时。在存在表皮层的情况下，t（eff）增加到 575.7 小时。这些结果可用于评估溶解和扩散对药物达到血液治疗水平所需时间的相对影响。
