Although used widely in cosmetic formulations, topical delivery of niacinamide (LogP = −0.35) is unfavorable by conventional means. Poly(lactide-co-glycolide) (PLGA) formulations, can undergo a sol-gel transition triggered by solvent exchange, entrapping molecules and sustaining their release. The current study aims to exploit the ability of PLGA to gel in situ and enhance the topical delivery of niacinamide in microporated skin. In vitro drug permeation studies were performed using vertical Franz diffusion cells. Microporation was performed using Dr. Pen^TM Ultima A6, where pre-treatment with a 1 mm needle-length for 10 s and a 0.5 mm needle-length for 5 s, both at 13,000 insertions/min were compared. The effect of different grades of PLGA, EXPANSORB^® DLG 50-2A ("low" molecular weight), and EXPANSORB^® DLG 50-8A ("high" molecular weight) on topical delivery was also determined. Formulations containing PLGA resulted in successful gelation in situ on application over microporated skin. A significantly higher amount of drug was found in the skin with the 0.5 mm treatment for 5 s (892 ± 36 µg/cm²) than with 1 mm for 10 s (167 ± 16 µg/cm²). Hence, the different grades of PLGA were evaluated with 0.5 mm, 5 s treatment, and a significantly larger amount was seen in skin with the higher rather than the lower molecular weight polymer (172 ± 53 µg/cm²).

中文翻译：

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在微孔皮肤中原位形成凝胶以增强烟酰胺的局部递送。

尽管广泛用于化妆品制剂中，但是烟酰胺的局部递送（LogP = -0.35）通过常规方法是不利的。聚（丙交酯-共-乙交酯）（PLGA）配方可经历由溶剂交换触发的溶胶-凝胶转变，截留分子并维持其释放。当前的研究旨在开发PLGA原位凝胶化的能力，并增强微孔皮肤中烟酰胺的局部递送。使用垂直Franz扩散池进行体外药物渗透研究。使用Dr. Pen ^TM Ultima A6进行微穿孔，其中比较了1mm针长10 s和0.5 mm针长5 s的预处理，均以13,000次插入/分钟进行。不同档次的PLGA，EXPANSORB的效果^®DLG 50-2A（“低”分子量），和EXPANSORB ^® DLG 50-8A（“高”分子量）上局部递送也被确定。含PLGA的制剂在微孔皮肤上施用后可成功地原位凝胶化。用0.5 mm处理5 s（892±36 µg / cm ²）比用1 mm处理10 s（167±16 µg / cm ²）在皮肤中发现的药物量要高得多。因此，用0.5 mm，5 s的处理评估了不同等级的PLGA，并且在皮肤上发现了较高分子量的聚合物而不是较低分子量的聚合物（172±53 µg / cm ²）。