Niacinamide Skin Absorption Mechanisms

Primary Absorption Pathways

• Niacinamide follows two main routes when applied to skin: the transdermal route, which is the primary pathway, and the appendageal route, which is minor, with the transdermal route diffusing through the lipidic matrix between cells 1, 2
• The appendageal route uses hair follicles and glands but represents only a minimal proportion of total skin area and is limited to particles with appropriate size (<500 Da) 1, 2

Molecular Properties Favoring Absorption

• Niacinamide's small molecular weight, well below the ideal 500 Da threshold for transdermal delivery, facilitates its skin penetration 1, 2

Clinical Considerations

• The American Academy of Dermatology supports the safety profile of topical niacinamide, which does not cause flushing unlike nicotinic acid, and is well-tolerated with antipruritic, antimicrobial, vasoactive, photoprotective, sebostatic and lightening effects depending on concentration 3, 4
• Skin integrity significantly affects absorption, with damaged tissues facilitating the process enormously 1, 2

Metabolism and Excretion

• Urinary metabolites can assess niacin status if needed, with primary metabolites including N1-methylnicotinamide and N1-methyl-4-pyridone-3-carboxamide, and excretion primarily through the urinary tract 3