Topical Corticosteroids

Topical Steroids: Intro & Action - Skin Soothers

• Synthetic analogs of natural corticosteroids; for localized skin inflammation & related conditions.
• Primary Actions:
  • Anti-inflammatory: Inhibit Phospholipase A2 (↓ prostaglandins, leukotrienes). Bind Glucocorticoid Receptors (GREs) → alter gene expression. ↓ inflammatory cytokine release.
  • Immunosuppressive: ↓ activity of lymphocytes & macrophages.
  • Anti-proliferative: ↓ DNA synthesis & mitosis in epidermal cells.
  • Vasoconstrictive: Reduces local blood flow & erythema.

⭐ Vasoconstriction (blanching) is a key mechanism of topical corticosteroids and forms the basis for potency assessment (e.g., Stoughton-McKenzie test).

Steroid Strength & Types - Potency Powerhouse

Topical corticosteroids grouped by potency; crucial for matching strength to condition & site.

• Potency Classes (US System):
  • Class I (Superpotent): Clobetasol propionate 0.05%, Halobetasol 0.05%
  • Class II (Potent): Fluocinonide 0.05%, Betamethasone dipropionate 0.05% (aug.)
  • Class III (Upper Mid-Strength): Betamethasone valerate 0.1%
  • Class IV (Mid-Strength): Triamcinolone acetonide 0.1% (cream/oint.)
  • Class V (Lower Mid-Strength): Fluocinolone acetonide 0.01%
  • Class VI (Mild): Desonide 0.05%, Alclometasone dipropionate 0.05%
  • Class VII (Least Potent): Hydrocortisone 1%, 2.5%

📌 Mnemonic (Examples I→VII): "Clever Foxes Bring Tasty Fish During Harvest"

• Formulation & Potency: Potency ↑ with occlusive vehicles.
  • Ointments (most potent) > Creams > Lotions > Gels > Solutions/Sprays (least potent).
  • Occlusion (e.g., plastic wrap) ↑ absorption significantly (e.g., 10-100x).

⭐ Clobetasol propionate is a superpotent (Class I) topical corticosteroid, while hydrocortisone (1%) is a mild (Class VII) one.

Uses & Application - Skin Savers

• Key Indications:
  • Eczemas (atopic, contact, seborrheic, discoid), Psoriasis (localized, non-plaque).
  • Lichen Planus, Lichen Sclerosus, DLE, severe insect bites.
• Application Guidelines:
  • Apply thinly 1-2 times/day; use Fingertip Unit (FTU) for quantity.
  • Shortest effective duration; taper frequency or potency on improvement.
  • Occlusion (e.g., under dressing) ↑ potency & absorption; use short-term, cautiously.
  • Avoid on ulcerated or untreated infected skin (unless specific antimicrobial combo).

⭐ One Fingertip Unit (FTU) is the amount of ointment expressed from a tube with a 5mm nozzle onto the adult index finger from tip to DIP joint, approximately 0.5g, which covers an area of two adult hands.

visual guide for topical steroid application)

Side Effects & Cautions - Handle With Care

Local Side Effects:

• Skin atrophy (thinning, fragility, easy bruising) - most common
• Telangiectasia, striae, purpura
• Acneiform eruptions, rosacea, perioral dermatitis
• Hypopigmentation
• Delayed wound healing
• Tachyphylaxis (tolerance)
• Allergic contact dermatitis (to steroid or vehicle)

Systemic Side Effects (rare with low-medium potency; risk with high potency, large area, prolonged use, occlusion):

• Hypothalamic-Pituitary-Adrenal (HPA) axis suppression
• Cushing's syndrome
• Growth retardation (children)
• Hyperglycemia, glaucoma

Cautions/Contraindications:

• Untreated bacterial, fungal, or viral skin infections (e.g., herpes simplex, varicella zoster)
• Hypersensitivity
• Use potent steroids cautiously on face, intertriginous areas, and in children.

⭐ Skin atrophy, characterized by thinning, fragility, and easy bruising, is the most common and characteristic local side effect of prolonged topical corticosteroid use.

⚠️ Avoid abrupt withdrawal after prolonged use; taper gradually to prevent rebound phenomenon. 📌 Skin atrophy, Telangiectasia, Rosacea, Infections, Pigmentation changes, Epidermal thinning, Delayed healing (STRIPED) for local effects (partial mnemonic).

High‑Yield Points - ⚡ Biggest Takeaways

• Mechanism: Anti-inflammatory, immunosuppressive, anti-proliferative via glucocorticoid receptors.
• Potency classification (low to superpotent) guides selection; e.g., hydrocortisone (low), clobetasol (superpotent).
• Site matters: Low potency for face/groin; high potency for palms/soles.
• Side effects: Skin atrophy, striae, telangiectasias, tachyphylaxis, systemic absorption.
• Tachyphylaxis: Rapid ↓ in drug response with repeated use.
• Occlusion significantly ↑ absorption and potency.
• Avoid abrupt withdrawal of potent steroids to prevent rebound phenomenon.