Hyperkeratinization* is a primary or fundamental event in a majority of today’s skin disorders. Hyperkeratinization is usually the result of decreased desquamation due to increased corneocyte cohesion. Strength of corneocyte cohesion is determined by strength of intercellular bonding. Intercellular bonding is weakened by water and diminished by retinoids and alpha hydroxyl acids (AHAs). Conversely, bonding is strengthened or enhanced by dehydration, vitamin A deficiency, and some alpha acetoxy acids (AAAs). Agents that control or modify keratinzation can be useful in treatment of many skin disorders.
Hyperkeratinzation – Excessive development of dead skin cells on skin surface
Corneocyte cohesion – Dead skin cells stuck to the surface of the skin
Removing of dead skin cells from skin surface
- HAs aid in regulating cell renewal through the exfoliation of dead skin cells.
- AHAs do not over exfoliate the skin, causing it to be thin. It separates the dead skin cells only when it is thick enough and ready.
Skin condition: Icthyosis vulgaris
Separation of dead skin cells from skin surface after using 5%
glycolic acid in hydrophilic ointment four times daily for 24 hours.
Promotes regularity of skin condition in as soon as 3 weeks
- HAs promote regularity of skin surface, improving the cosmeticity of the skin.
- AHAs are effective for skin conditions related to excessive dead skin layers on skin surface.
- Follicular hyperkeratinization of keratosis pilaris and acne comedones respond well to topical AHAs.
(Left) Skin condition: Lamellar ichthyosis
(Right) After application of 4 times daily of 5% glycolic aicd in hydrophilic ointment for 1 week and once daily for the next 2 weeks.