Topical Corticosteroids

Topical Corticosteroids: Intro & MOA - Steroid Superpowers

Synthetic steroids for skin conditions, possessing four key "superpowers":

• Anti-inflammatory
• Immunosuppressive
• Anti-proliferative
• Vasoconstrictive

MOA: Primarily genomic, also non-genomic.

• Genomic: Diffuse into cells, bind cytosolic glucocorticoid receptors. Complex translocates to nucleus.
  • Upregulates anti-inflammatory proteins like lipocortin-1 (annexin-1).
  • Lipocortin-1 inhibits phospholipase A2, blocking synthesis of prostaglandins & leukotrienes.
• Non-genomic: Rapid, less understood membrane-mediated effects.

⭐ Vasoconstriction (blanching) is the basis of the McKenzie-Stoughton assay for assessing TCS potency.

Topical Corticosteroids: Potency Classification - Strength Spectrum Showdown

⭐ Clobetasol propionate 0.05% is a Class I (superpotent) topical corticosteroid.

Topical Corticosteroids: Skin Absorption & Vehicles - Delivery Dynamics

Percutaneous absorption influenced by:

• Occlusion: Greatly ↑ absorption.
• Vehicle: Type impacts penetration.
• Site: E.g., scrotum > forehead > scalp.
• Age: ↑ absorption in young/old.
• Skin Integrity: ↑ if damaged.

Topical Corticosteroids: Clinical Uses & Smart Strategies - Healing Helpers

• Key Indications: Inflammatory & hyperproliferative conditions.
  • Eczema/Dermatitis (atopic, contact, seborrheic).
  • Psoriasis (localized, non-facial).
  • Lichen Planus, Discoid Lupus Erythematosus.
  • Vitiligo (often adjunctive).
  • Alopecia Areata.
• Rational Use Principles:
  • Potency: Use lowest effective potency.
  • Duration: Shortest possible; avoid prolonged use.
  • Vehicle: Ointments (dry/thick), creams (versatile), lotions/gels (hairy areas).
  • Site: Lower potency for face, genitals, intertriginous areas, children.
  • Tapering: Gradually reduce frequency/potency to prevent rebound.

⭐ One Fingertip Unit (FTU) is approximately 0.5g and covers an area equivalent to two adult handprints.

Topical Corticosteroids: Adverse Effects - The Caution Zone

• Local Effects: Common, especially with high potency or prolonged use.
  • Skin atrophy, striae (irreversible), telangiectasias, purpura.
  • Acneiform eruptions, perioral dermatitis, steroid rosacea.
  • Tachyphylaxis (↓ response over time).
  • Delayed wound healing, increased skin infections.
  • Allergic or irritant contact dermatitis.
• Systemic Effects: Risk ↑ with high potency, large area, occlusion, prolonged use, children.
  • Hypothalamic-Pituitary-Adrenal (HPA) axis suppression.
  • Iatrogenic Cushing's syndrome.
  • Growth retardation (children).
  • Hyperglycemia, unmasking latent diabetes.
  • Ocular: Cataracts (posterior subcapsular), glaucoma.

⭐ Tachyphylaxis, a diminished response to a drug after repeated use, is a known phenomenon with topical corticosteroids.

High‑Yield Points - ⚡ Biggest Takeaways

• Mechanism: Anti-inflammatory, immunosuppressive, anti-proliferative, vasoconstrictive.
• Potency Classes: Class I (e.g., Clobetasol) is superpotent; Class VII (e.g., Hydrocortisone) is least potent.
• Absorption Factors: ↑ with thin skin (scrotum, eyelids), occlusion, vehicle, and inflamed skin.
• Key Local Side Effects: Skin atrophy, striae, telangiectasias, acneiform eruptions, tachyphylaxis.
• Systemic Side Effects: Risk of HPA axis suppression with high potency, large areas, prolonged use, or occlusion.
• Rational Use: Choose lowest effective potency for shortest duration; consider site and age.