What is the proper usage and guidance for topical PUVA (psoralen and ultraviolet A) therapy, specifically the brand Oxsoralen Ultra (8-methoxypsoralen), in an infant or child with severe psoriasis or vitiligo?

How to Use Topical PUVA: Brand and Clinical Guidance

For topical PUVA therapy, use 0.1% 8-methoxypsoralen (Oxsoralen Ultra brand) in an emollient base, applied 30 minutes before UVA exposure, starting at 0.25-0.5 J/cm² and treating 2-3 times per week for localized psoriasis of palms and soles in adults. 1

Critical Contraindication for Pediatric Use

PUVA therapy should be undertaken with great caution in children due to photocarcinogenicity, and bath PUVA is strongly preferred over topical or oral PUVA in pediatric patients because of lowered systemic absorption. 1 For children with severe psoriasis or vitiligo, the British Journal of Dermatology recommends topical calcineurin inhibitors (tacrolimus 0.1% or pimecrolimus 1%) as first-line therapy instead of PUVA, with narrowband UVB phototherapy as the preferred phototherapy option when topical treatments fail. 2

Topical PUVA Protocol for Adults

Indications

• Primary indication: Psoriasis of palms and soles in adults 1
• Alternative: Bath PUVA for generalized psoriasis in adults and children (preferred over topical in children) 1

Brand and Formulation

• Brand name: Oxsoralen Ultra (8-methoxypsoralen) 1
• Topical concentration: 0.1% 8-methoxypsoralen in emollient base 1
• Bath formulation: 50 mg of 8-methoxypsoralen (Oxsoralen Ultra) dissolved in 100 liters of water 1

Application Protocol

Topical Application:

• Apply 0.1% 8-methoxypsoralen in emollient 30 minutes before UVA exposure 1
• Treat 2-3 times per week 1
• Starting dose: 0.25-0.5 J/cm² UVA 1
• Dose escalation: Increase by 0.25-0.5 J/cm² at each treatment 1

Bath PUVA:

• Immerse in bath containing 50 mg 8-methoxypsoralen in 100 L water for 20-30 minutes pre-exposure 1
• Follow similar treatment schedule as oral PUVA 1

Treatment Duration and Response

• Initial response: May take 30 treatments to see noticeable improvement 1
• Single course: Usually 30-40 treatments 1
• Remission duration: 3-12 months after clearance 1
• Maintenance treatment may be used once clearance is achieved 1

Absolute Contraindications

Never use topical PUVA in patients with:

• Lupus erythematosus 1
• Porphyria 1
• Xeroderma pigmentosum 1

Use with Extreme Caution In

• Skin types I and II (burn easily) 1
• History of arsenic intake or previous ionizing radiation therapy 1
• History of melanoma or multiple nonmelanoma skin cancers 1
• Pregnancy or nursing (Category C) 1
• Patients previously treated with cyclosporine or methotrexate 1

Critical Safety Advantages of Topical vs. Oral PUVA

Topical PUVA has a superior safety profile compared to oral PUVA:

• No increased risk of skin cancer demonstrated with topical PUVA 1
• Psoralen is not detectable in blood when washed off after use in palmoplantar psoriasis 1
• However, systemic levels may be detectable if applied over large body surface area 1
• No systemic absorption studies performed in children, but considered safer than oral PUVA 1

Monitoring Requirements

Baseline monitoring:

• None required for topical PUVA 1

Ongoing monitoring:

• Monitor for efficacy and burning 1
• No routine skin cancer screening required (unlike oral PUVA which requires annual screening after 150-200 treatments) 1

Acute Toxicity Management

Common acute side effects:

• Erythema 1
• Blistering 1
• Hyperpigmentation 1

If erythema occurs:

• Do not increase UVA dose until erythema resolves 3
• May need to shorten, omit, or maintain previous dosage based on severity 3

Drug Interactions

No significant drug interactions with topical PUVA 1 (unlike oral PUVA which interacts with photosensitizing medications including NSAIDs, diuretics, tetracyclines, and fluoroquinolones) 1

Special Populations

Pregnancy

• Category C 1
• No epidemiologic studies evaluating congenital anomalies with topical PUVA during pregnancy 1
• Topical psoralen not detectable in blood when washed off, but may be detectable with large surface area application 1

Nursing

• No data available for topical PUVA 1
• Oral psoralen contraindicated for 24 hours after ingestion 1

Pediatric Use

• Safe provided patient can follow instructions 1
• No systemic absorption studies performed in children 1
• Bath PUVA preferred over topical or oral PUVA in children due to minimal systemic absorption 1, 4
• One case report demonstrates successful treatment of 9-year-old with vitiligo using bath PUVA 4

Critical Pitfalls to Avoid

• Never use topical PUVA as first-line therapy in children—use topical calcineurin inhibitors or narrowband UVB instead 2
• Never apply over large body surface areas without considering systemic absorption risk 1
• Never combine with cyclosporine due to accelerated skin cancer risk 1
• Never use in patients with photosensitivity disorders (lupus, porphyria, xeroderma pigmentosum) 1
• Never increase UVA dose when erythema is present—wait for resolution 3