Water-in-oil microemulsions composed of monoolein enhanced the transdermal delivery of nicotinamide

Momoko Kitaoka, Trung Cong Nguyen, Masahiro Goto

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Objective: Nicotinamide, also known as niacinamide, is a water-soluble vitamin that is used to prevent and treat acne and pellagra. It is often found in water-based skin care cosmetics because of its high water solubility. Nicotinamide is a small molecule with a molar mass of 122.1 g/mol. However, it has a hydrophilic nature that becomes an obstacle when it penetrates through the skin. The topmost layer of the skin, the stratum corneum, acts as a strong hydrophobic barrier for such hydrophilic molecules. The oil-based formulations are expected to enhance the transdermal delivery efficiency of nicotinamide. Methods: We have developed oil-based microemulsion formulations composed of a squalane vehicle. Monoolein was used as an emulsifier that has a potential to enhance the nicotinamide delivery through the stratum corneum. Results: Because the mean size of the emulsions measured by dynamic light scattering was 20.9 ± 0.4 nm, the microemulsion formulation was stable under the long-term storage. Monoolein acted as a skin penetration enhancer, and it effectively enabled the penetration of nicotinamide through human abdominal skin, compared with nicotinamide in a phosphate-buffered saline solution. The flux was increased 25-fold. Microscopic imaging revealed that the hydrophilic bioactive compounds penetrated through the intercellular spaces in the epidermis. Conclusion: The monoolein-based microemulsion was transparent and stable, suggesting that it is a promising formulation for a transdermal nicotinamide delivery.

Original languageEnglish
Pages (from-to)302-310
Number of pages9
JournalInternational Journal of Cosmetic Science
Issue number3
Publication statusPublished - Jun 2021

All Science Journal Classification (ASJC) codes

  • Chemistry (miscellaneous)
  • Ageing
  • Pharmaceutical Science
  • Drug Discovery
  • Dermatology
  • Colloid and Surface Chemistry


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