Dermal fillers are gel-type substances for nonsurgical medical-device use to achieve facial rejuvenation. Currently, the most widely used skin fillers are hyaluronic-acid-based dermal fillers. This study aimed to explain the change in the volume of injected dermal fillers by developing a mathematical kinetic model for various dermal fillers. The kinetics of the injected fillers were separated by a biphasic phenomenon. We attributed an increase in filler volume to the hydration of hyaluronic acid molecules and injection-site reaction and a decrease in volume to enzyme-mediated degradation. To explain these in vivo characteristics of dermal fillers, we proposed a two-compartment model, divided into a depot compartment (where the filler was injected) and a subcutaneous compartment (an observation compartment where the fillers swell and degrade), assuming that the swelling and degradation occurred in accordance with the swelling and degradation rate constants, respectively. The model was developed using five hyaluronic-acid-based dermal fillers and NONMEM. We determined that the rate-limiting step for the complete degradation of the dermal fillers in vivo was the swelling phase, as described by the swelling rate constant (K_swell). This study could enable scientists developing novel dermal fillers to predict the in vivo behavior of fillers.

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基于模型的预测，以评估透明质酸基皮肤填充剂的停留时间

皮肤填充剂是用于非手术医疗设备的凝胶型物质，可实现面部年轻化。当前，最广泛使用的皮肤填充剂是透明质酸基皮肤填充剂。这项研究旨在通过开发各种真皮填充剂的数学动力学模型来解释注射的真皮填充剂体积的变化。注入的填料的动力学被两相现象分开。我们将填料体积的增加归因于透明质酸分子的水合和注射部位反应，而体积的减少归因于酶介导的降解。为了解释真皮填充剂的这些体内特性，我们提出了一种两室模型，分为储库隔室（注射填充剂）和皮下隔室（观察剂填充物溶胀和降解）。假设溶胀和降解分别根据溶胀和降解速率常数发生。使用五种基于透明质酸的真皮填充剂和NONMEM开发了该模型。我们确定，体内完全降解真皮填充剂的限速步骤为溶胀阶段，如溶胀速率常数（K_膨胀）。这项研究可以使科学家开发出新型的真皮填充剂来预测填充剂的体内行为。