Keratolytics and Emollients

Keratolytics - Skin Peel Power

*Agents that soften, loosen, and promote exfoliation of the stratum corneum.

• Mechanism: Disrupt corneocyte adhesion, ↑ cell turnover, leading to desquamation.
• Key Agents & Specifics:
  • Salicylic Acid (BHA):
    • MOA: Solubilizes intercellular cement; desquamates. Lipophilic.
    • Uses: Acne (comedonal), warts, corns, psoriasis.
    • Caution: Salicylism (rare with topical use on limited areas).
  • Alpha-Hydroxy Acids (AHAs): (e.g., Glycolic, Lactic acid)
    • MOA: ↓ corneocyte cohesion. Exfoliates.
    • Uses: Photoaging, xerosis, acne, superficial scars.
  • Urea:
    • MOA: Hydrating (<10%); keratolytic, protein denaturant (>10%-40%).
    • Uses: Ichthyosis, severe xerosis, calluses, nail avulsion.
  • Sulfur: Mild keratolytic, antifungal, antibacterial.
    • Uses: Acne, rosacea, seborrheic dermatitis.
  • Propylene Glycol: Vehicle, humectant; enhances keratolysis.
  • Retinoids (e.g., Tretinoin): Induce desquamation by ↑ epidermal cell turnover (not primary keratolytics).
• General Uses: Hyperkeratotic disorders, acne, psoriasis, warts.
• Side Effects: Irritation, dryness, erythema, peeling. Photosensitivity (AHAs, Retinoids).

⭐ Salicylic acid is particularly effective for comedonal acne due to its lipophilic nature, allowing penetration into sebaceous follicles.

Emollients & Moisturizers - Barrier Boosters

• Goal: Hydrate stratum corneum, restore skin barrier, ↓TEWL.
• Types & Action:
  • Occlusives: Form surface film, block water loss. Best for very dry skin.
    • Petrolatum (↓TEWL >98%), lanolin, mineral oil, dimethicone.
  • Humectants: Attract water to epidermis (from dermis/air if humidity >70%). May irritate sensitive skin.
    • Glycerin, urea (<10%), propylene glycol, hyaluronic acid, lactic acid (AHA).
  • Emollients (Repair): Smooth skin, fill inter-corneocyte lipid gaps, restore barrier components.
    • Ceramides, cholesterol, fatty acids, squalene.
• Uses: Xerosis, atopic dermatitis (AD), psoriasis, ichthyosis, general dry skin relief.
• Apply: Liberally, often, especially post-bath (damp skin, within 3 min).

⭐ Ceramides: Crucial stratum corneum lipids. Deficiency is key in atopic dermatitis, impairing barrier integrity and promoting transepidermal water loss (TEWL).

Clinical Applications - Smart Skin Solutions

Emollients treat xerosis/eczema, improving barrier. Keratolytics manage hyperkeratosis via desquamation.

• Salicylic Acid: Acne, warts (conc. up to 40% for plasters), psoriasis.
• Urea: Hydrating (<10%), keratolytic (>10%); for ichthyosis, severe xerosis.
• AHAs (Glycolic/Lactic acid): Photoaging, acne, mild xerosis.
• Often combined: Emollients + keratolytics for ichthyosis.

⭐ High concentrations of salicylic acid (>6%) applied extensively can lead to salicylism, especially in children.

High‑Yield Points - ⚡ Biggest Takeaways

• Keratolytics (e.g., Salicylic acid, Urea, AHAs) promote desquamation by dissolving intercellular substance, used in psoriasis or acne.
• Salicylic acid (BHA) is comedolytic and keratolytic; watch for salicylism with widespread use.
• Urea exhibits concentration-dependent effects: humectant (<10%) or keratolytic (>10%).
• Alpha-hydroxy acids (AHAs) like Glycolic acid exfoliate the epidermis, used for photoaging and ichthyosis.
• Emollients (e.g., Petrolatum, Lanolin) hydrate skin by occlusion, reducing transepidermal water loss (TEWL).
• Topical retinoids (e.g., Tretinoin, Adapalene) normalize keratinization and are comedolytic; strictly teratogenic.