Topical Therapy for Psoriasis

Topical Corticosteroids - Potent Skin Soothers

• MOA: Anti-inflammatory, immunosuppressive, anti-proliferative.
• Classification (Potency I-VII):
  • I (Superpotent): Clobetasol propionate
  • IV (Mid-potency): Mometasone furoate
  • VII (Least potent): Hydrocortisone
• Indications: Plaque psoriasis; site-specific choice: Scalp (lotions/foams), Face/Flexures (low potency), Trunk/Limbs (mid-high potency).
• Local Side Effects: Atrophy, striae, telangiectasia, acneiform eruptions, tachyphylaxis. 📌 ASTAT.
• Systemic Side Effects: HPA axis suppression (↑potency, ↑area, ↑duration, occlusion).
• Use: Limit potent steroids to 2-4 weeks. Taper gradually to prevent rebound.

⭐ Tachyphylaxis (rapidly diminishing response) can occur with continuous use, necessitating "steroid holidays" or a switch in therapy to maintain efficacy for chronic psoriasis management.

Vitamin D Analogs - Sunshine Power

• Examples: Calcipotriol (Calcipotriene), Calcitriol, Tacalcitol.
• MOA: Bind Vitamin D Receptors (VDR) → ↓ keratinocyte proliferation, ↑ differentiation, modulate inflammation.
• Efficacy: Comparable to mid-potency steroids for mild-moderate plaque psoriasis.
• Combination: With steroids (e.g., Calcipotriol/Betamethasone) ↑ efficacy, ↓ steroid side effects.

  ⭐ Calcipotriol/betamethasone dipropionate fixed combination is highly effective and improves adherence.

• Side Effects: Local irritation (burning, itching). ⚠️ Risk of hypercalcemia/hypercalciuria with excessive use (e.g., Calcipotriol max ~100g/week).

Tazarotene & TCIs - Targeted Modulators

• Tazarotene (Topical Retinoid)
  • MOA: Binds Retinoic Acid Receptors (RARs); normalizes keratinocyte differentiation & proliferation; anti-inflammatory.
  • Indications: Plaque psoriasis, especially thicker plaques.
  • Side Effects: Application site irritation, erythema, burning, photosensitivity.
  • ⚠️ Teratogenic: Pregnancy Category X 📌.
• Topical Calcineurin Inhibitors (TCIs)
  • Examples: Tacrolimus, Pimecrolimus.
  • MOA: Inhibit calcineurin → ↓ T-cell activation & inflammatory cytokine release.
  • Use (Off-label for Psoriasis): Facial, flexural, genital areas (steroid-sparing).
  • Side Effects: Burning/stinging on application; ⚠️ Black box warning (rare lymphoma risk, causality unclear).

⭐ Tazarotene is strictly Category X in pregnancy; effective contraception is mandatory for women of childbearing potential.

Other Classic Agents - Tried & True

• Coal Tar:
  • MOA: Anti-proliferative, anti-inflammatory.
  • Prep: Crude coal tar (CCT), refined tar extracts.
  • Goeckerman regimen: CCT + UVB 📌.
  • SE: Folliculitis, photosensitivity, staining, strong odor.
• Salicylic Acid:
  • MOA: Keratolytic; enhances other topical penetration.
  • Conc: 2-10% for thick, hyperkeratotic plaques.
  • ⚠️ Caution: Salicylism risk with large area application.
• Anthralin (Dithranol):
  • MOA: Inhibits DNA synthesis, anti-proliferative.
  • Apply: SCAT 📌 (Short Contact Anthralin Therapy), Ingram regimen 📌.
  • SE: Irritation, purple-brown staining (skin/clothes).

  ⭐ Anthralin causes characteristic purple-brown staining of skin and clothes, a key identifier.

Topical Treatment Strategies - Smart Combos

• Rationale: ↑efficacy, ↓side effects, faster onset.
• Common Combos:
  • Corticosteroid (CS) + Vit D analog (e.g., calcipotriol/betamethasone)
  • CS + Salicylic acid
  • CS + Tazarotene (↑efficacy, ↓irritation)
• Therapeutic Approaches:
  • Sequential: Potent CS (initial) → Vit D analog/less potent CS (maintenance).
  • Rotational: Cycle drugs (↓toxicity, ↓tachyphylaxis).
  • Proactive/Maintenance: Intermittent use (e.g., 2x/week) on healed areas.
• Influencing Factors: Severity (BSA, PASI), location, morphology, patient preference.

⭐ Calcipotriol/betamethasone dipropionate fixed combo is effective for initial treatment and proactive "weekend" therapy (2x/week) to maintain remission.

High‑Yield Points - ⚡ Biggest Takeaways

• Topical corticosteroids: First-line; match potency to site/severity. Monitor for skin atrophy.
• Vitamin D analogues (calcipotriol): Effective steroid-sparing agents, inhibit keratinocyte proliferation. Max 100g/week.
• Tazarotene: Potent topical retinoid. Highly teratogenic (Pregnancy Category X); irritation common.
• Calcineurin inhibitors (tacrolimus): Preferred for sensitive areas like face/flexures, no skin atrophy.
• Coal tar: Reduces inflammation/scaling. Downsides: staining, odor, photosensitivity. Used in Goeckerman.
• Combination therapy (e.g., steroid + Vit D analogue): Maximizes efficacy, minimizes side effects.