Zhao Shengnan, Zuo Jieyu, Mallillin Marlon C, Tang Ruikun, Doschak Michael R, Davies Neal M, Löbenberg Raimar
Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB T6G 2E1, Canada.
China Z. Pharmaceutical Productivity Centre, Beijing 101111, China.
Pharmaceuticals (Basel). 2025 Jun 13;18(6):889. doi: 10.3390/ph18060889.
: Ex vivo nasal mucosa models provide physiologically relevant platforms for evaluating nasal drug permeability; however, their application is often limited by high experimental variability and the absence of standardized methodologies. This study aimed to improve experimental design by addressing two major limitations: the confounding effects of mucosal thickness and the questionable reliability of fluorescein sodium (Flu-Na) as an integrity marker for chemically induced mucosal injury. : Permeability experiments were conducted using porcine nasal tissues mounted in Franz diffusion cells, with melatonin and Flu-Na as model compounds. Tissues of varying thickness were collected from both intra- and inter-individual sources, and a numerical simulation-based method was employed to normalize apparent permeability coefficients (Papp) to a standardized mucosal thickness of 0.80 mm. The effects of thickness normalization and chemically induced damage were systematically evaluated. : Thickness normalization substantially reduced variability in melatonin Papp, particularly within same-animal comparisons, thereby improving statistical power and data reliability. In contrast, Flu-Na exhibited inconsistent correlations across different pigs and failed to reflect the expected increase in permeability following isopropyl alcohol (IPA)-induced epithelial damage. These results suggest that the relationship between epithelial injury and paracellular transport may be non-linear and not universally applicable under ex vivo conditions, limiting the suitability of Flu-Na as a standalone marker of mucosal integrity. : The findings highlight the importance of integrating mucosal thickness correction into standardized experimental protocols and call for a critical reassessment of Flu-Na in nasal drug delivery research.
离体鼻黏膜模型为评估鼻腔药物渗透性提供了生理相关的平台；然而，其应用常常受到高实验变异性和缺乏标准化方法的限制。本研究旨在通过解决两个主要限制来改进实验设计：黏膜厚度的混杂效应以及荧光素钠（Flu-Na）作为化学诱导黏膜损伤完整性标志物的可靠性存疑。
使用安装在Franz扩散池中的猪鼻组织进行渗透性实验，以褪黑素和Flu-Na作为模型化合物。从个体内和个体间来源收集不同厚度的组织，并采用基于数值模拟的方法将表观渗透系数（Papp）归一化为标准化黏膜厚度0.80毫米。系统评估了厚度归一化和化学诱导损伤的影响。
厚度归一化显著降低了褪黑素Papp的变异性，尤其是在同一只动物的比较中，从而提高了统计效力和数据可靠性。相比之下，Flu-Na在不同猪之间表现出不一致的相关性，并且未能反映异丙醇（IPA）诱导上皮损伤后预期的渗透性增加。这些结果表明，上皮损伤与细胞旁转运之间的关系可能是非线性的，并且在离体条件下并非普遍适用，这限制了Flu-Na作为黏膜完整性单一标志物的适用性。
这些发现突出了将黏膜厚度校正纳入标准化实验方案的重要性，并呼吁在鼻腔药物递送研究中对Flu-Na进行批判性重新评估。
