Permeation studies of Niacinamide and its effect on human skin

Abstract:  Background: Niacinamide (NIA) is one of the most commonly used cosmetic ingredients. It belongs to the vitamin-B3 family and has extensive dermatological therapeutic benefits. NIA has been proven to be a useful skincare product in serving as anti-acne agent, preventing skin hyperpigmentation, removal of wrinkles from the face etc.  Aim: To investigate permeability patterns of NIA, its effect on electrical impedance of the skin membrane and the role it plays in maintaining the hydration of stratum corneum (SC). For this, permeation, chromatography, sorption isotherm and X-ray studies were performed. Results: NIA permeation was observed to correlate with pH and it permeated more when delivered in PBS at pH 7.4 as compared to its permeation in citrate buffer at pH 5. Moreover, skin resistance also increased by Ca. 47% in relation to NIA permeation at pH-5 while it decreased by an average of 45% at pH 7.4. In addition, vapor sorption analysis showed that NIA increased the hydration of SC at 95%RH as compared to buffer controls. This was also supported by X-ray data where NIA treated SC samples were shown to have larger interchain spacing in their keratin filaments in comparison to SC in buffer controls. This increase is usually associated with an increase in the water content of SC and thus NIA might have similar beneficial effects as water and can even be more advantageous as it doesn’t evaporate in dehydrated states unlike water. Moreover, artificial skin model has also been tested in parallel, and it was significantly more permeable to NIA than the human skin. Hence some modifications are necessary before it can be used to replace human/porcine skin. Conclusion: The study showed that pH influences NIA permeation and resistance of skin membrane. Additionally, NIA play beneficial roles by increasing water content of SC at high relative humidity (RH%).