Energy-Dependent Endocytosis Is Responsible for Skin Penetration of Formulations Based on a Combination of Indomethacin Nanoparticles and l-Menthol in Rat and Göttingen Minipig

• Published in: International journal of molecular sciences 2021-05, Vol.22 (10), p.5137
• Main Authors: Otake, Hiroko, Yamaguchi, Mizuki, Ogata, Fumihiko, Deguchi, Saori, Yamamoto, Naoki, Sasaki, Hiroshi, Kawasaki, Naohito, Nagai, Noriaki
• Format: Article
• Language: English
• Subjects: Caveolae; Clathrin; Drug delivery systems; Drugs; Endocytosis; Epidermis; Indomethacin; Inhibitors; l-menthol; Menthol; Metabolism; nanoparticle; Nanoparticles; Nystatin; Oral administration; Particle size; Permeability; Pharmacology; Physical properties; Skin; Stratum corneum; transdermal delivery system; Transdermal medication; Viscosity
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms22105137

We previously designed a Carbopol gel formulation (N-IND/MEN) based on a combination of indomethacin solid nanoparticles (IND-NPs) and l-menthol, and we reported that the N-IND/MEN showed high transdermal penetration. However, the detailed mechanism for transdermal penetration of IND-NPs was not clearly defined. In this study, we investigated whether endocytosis in the skin tissue of rat and Göttingen minipig is related to the transdermal penetration of IND-NPs using pharmacological inhibitors of endocytosis. The pharmacological inhibitors used in this study are as follows: 54 µM nystatin, a caveolae-mediated endocytosis (CavME) inhibitor; 40 µM dynasore, a clathrin-mediated endocytosis (CME) inhibitor; and 2 µM rottlerin, a micropinocytosis (MP) inhibitor. The N-IND/MEN was prepared by a bead mill method, and the particle size of solid indomethacin was 79–216 nm. In both rat and Göttingen minipig skin, skin penetration of approximately 80% IND-NPs was limited by the stratum corneum (SC), although the penetration of SC was improved by the combination of l-menthol. On the other hand, the treatment of nystatin and dynasore decreased the transdermal penetration of indomethacin in rats and Göttingen minipigs treated with N-IND/MEN. Moreover, in addition to nystatin and dynasore, rottlerin attenuated the transdermal penetration of IND-NPs in the Göttingen minipigs’ skin. In conclusion, we found that l-menthol enhanced the SC penetration of IND-NPs. In addition, this study suggests that the SC-passed IND-NPs are absorbed into the skin tissue by energy-dependent endocytosis (CavME, CME, and/or MP pathways) on the epidermis under the SC, resulting in an enhancement in transdermal penetration of IND-NPs. These findings provide significant information for the design of nanomedicines in transdermal formulations.