Phototherapy Protocols

Phototherapy Basics - Ray Foundations

• Phototherapy: Utilizes non-ionizing electromagnetic radiation, mainly ultraviolet (UV) light, for therapeutic effects on skin.
• Key UV Bands & Skin Interaction:
  • UVA: 320-400 nm. Longest wavelength, penetrates deepest (dermis).
    • UVA1: 340-400 nm; UVA2: 320-340 nm.
  • UVB: 290-320 nm. Biologically most active for skin diseases; penetrates epidermis.
    • NB-UVB (Narrowband): 311-313 nm, highly effective.
  • UVC: 200-290 nm. Germicidal; mostly filtered by Earth's ozone layer.

⭐ Action spectrum for psoriasis treatment is most effective around 311 nm (NB-UVB).

NB-UVB Therapy - Narrow-Beam Power

• Wavelength: 311-313 nm (peak emission).
• Mechanism: Primarily immunomodulatory (affects T-cells, cytokines). Antiproliferative.
• Key Uses: Psoriasis, vitiligo, atopic dermatitis, early mycosis fungoides.
• Starting Dose Strategy:
  • Skin type-based: e.g., Type I-II: 0.1-0.2 J/cm²; Type III-IV: 0.2-0.3 J/cm²; Type V-VI: 0.3-0.4 J/cm².
  • MED-based: Typically 70% of Minimal Erythema Dose (MED).
• Regimen: 2-3 sessions/week. Dose increment 10-20% per session (guided by erythema).
• Advantages: More effective & safer than broadband UVB. No psoralens required (unlike PUVA).
• Considerations: Erythema, pruritus common. Monitor cumulative exposure for long-term photoaging.

⭐ NB-UVB is a first-line phototherapy for moderate-to-severe psoriasis due to its efficacy and favorable safety profile.

PUVA Therapy - Psoralen Power-Up

Psoralen + UVA (320-400nm). Psoralens (e.g., 8-Methoxypsoralen/8-MOP) are photosensitizers.

• Mechanism: Psoralen intercalates DNA; UVA activation cross-links DNA, inhibiting cell proliferation.
• Key Details:
  • Oral 8-MOP: 0.6 mg/kg, 1.5-2 hrs before UVA.
  • Delivery: Oral, bath, topical.
  • Indications: Severe psoriasis, vitiligo, mycosis fungoides.
• Side Effects:
  • Acute: Nausea, phototoxic erythema.
  • Chronic: Photoaging, ↑ skin cancer risk (SCC). 📌 PUVA Problems: Pigment changes, UV sensitivity, Vomiting, Aging/Malignancy.
• Protection: UVA-blocking eyewear for 24 hrs post-psoralen.

⭐ Long-term PUVA significantly increases squamous cell carcinoma (SCC) risk.

Targeted Phototherapy & PDT - Precision Beams

• Targeted Phototherapy: Delivers UV to lesions, spares healthy skin.
  • Excimer Laser: 308 nm (XeCl).
    • Indications: Localized psoriasis, vitiligo, alopecia areata, mycosis fungoides.
    • Rapid, high fluence.
  • Excimer Lamp: 308 nm. Larger spot.
• Photodynamic Therapy (PDT):
  • Mechanism: Photosensitizer + Light + O₂ → ROS → cell death.
  • Photosensitizers: Topical 5-ALA, MAL.
  • Light: Blue (~417 nm for ALA), Red (~635 nm for MAL).
  • Indications: Actinic keratosis (AK), superficial Basal Cell Carcinoma (sBCC), Bowen's disease.
  • Pain during illumination.

⭐ Excimer laser allows rapid delivery of high fluences to affected skin, sparing normal skin. oka

Protocol Pointers & Safety - Charting Choices

High‑Yield Points - ⚡ Biggest Takeaways

• NBUVB (311-313 nm): Preferred for psoriasis, vitiligo due to high efficacy & safety.
• PUVA: Psoralens (oral/topical) followed by UVA (320-400 nm); potent but with risks.
• MED (Minimal Erythema Dose): Essential for determining initial UVB therapy dose.
• Long-term PUVA significantly ↑ risk of photoaging & squamous cell carcinoma (SCC).
• Classic regimens for psoriasis: Goeckerman (crude coal tar + UVB) & Ingram (anthralin + UVB).
• Standard phototherapy frequency is 2-3 sessions per week.