Generic
Methoxsalen
3 brands available in the market
At a glance
Methoxsalen is used for vitiligo and psoriasis in combination with controlled ultraviolet light. It increases skin reactivity and inhibits DNA synthesis and cell division.
Description
Methoxsalen is a psoralen compound used as part of PUVA (Psoralen + UVA) therapy. It increases skin reactivity to long-wavelength UVA radiation. Methoxsalen forms covalent bonds with DNA (both monofunctional and bifunctional) to inhibit DNA synthesis and cell division, leading to cell injury. This effect is used in photochemotherapy or PUVA.
Indications
- Idiopathic vitiligo - repigmentation
- Severe, recalcitrant psoriasis - symptomatic control (when confirmed by biopsy)
Therapeutic class
Methoxsalen Preparation
Pharmacological class
Psoralen Derivative
Pharmacology
Methoxsalen increases skin reactivity to UVA radiation. It forms covalent bonds with DNA to inhibit DNA synthesis and cell division.
Mechanism of action
Treats vitiligo and psoriasis by inhibiting skin cell growth and reactivating melanocytes.
Dosage
Vitiligo (Oral):
- Two capsules (10 mg each) with milk or food, 2-4 hours before UVA exposure
- Sunlight exposure: Gradually increase (initial 15-25 minutes)
- Therapy on alternate days (not two consecutive days)
Psoriasis (Oral): Weight-based dosing: <30 kg: 10 mg; 30-50: 20 mg; 51-65: 30 mg; 66-80: 40 mg; 81-90: 50 mg; 91-115: 60 mg; >115: 70 mg (2 hours before UVA exposure)
Administration
- Swallow capsules whole; do not chew, crush or break
- Take with milk or food (to reduce nausea)
- Hands applying lotion should be protected with gloves (to avoid photosensitization)
Missed dose
Not generally applicable (scheduled dosing); consult doctor if needed.
Side effects
Common Side Effects (≈10%):
- Nausea
- Nervousness, insomnia, psychological depression
- Skin itching and redness
Precautions & warnings
- Serious burns from UVA or sunlight can occur (follow recommended dosage and exposure schedules)
- Risk of skin cancer (especially in fair-skinned patients)
- Eye protection: Use UVA-absorbing wrap-around sunglasses
- Do not sunbathe 24 hours prior to methoxsalen ingestion
- Wear protective clothing for 8 hours after treatment
Contraindications
- Hypersensitivity
- Aphakia
- Melanoma or history of melanoma
- Invasive squamous cell carcinoma
- Photosensitivity diseases (porphyria, lupus erythematosus, xeroderma pigmentosum)
Drug interactions
- Additive effects with other photosensitizing drugs (anthralin, coal tar, nalidixic acid, tetracyclines, thiazides)
- May increase plasma concentrations of drugs metabolized by CYP2A6 isoenzyme
Food interactions
Safety with alcohol is not known; consult your doctor.
Use in pregnancy
Use in Pregnancy: Methoxsalen is unsafe during pregnancy (Category C); evidence of risk to the fetus. Use only if clearly needed.
Pregnancy Category: C — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Use with caution during breastfeeding; hold breastfeeding until treatment is completed and drug is eliminated.
Pediatric use
Safety not established in children under 12 years; dose established for children 12 years+.
Geriatric use
No special dose adjustment may be needed in elderly.
Renal / hepatic impairment
Renal Impairment: Limited information available; consult your doctor.
Hepatic Impairment: Caution in liver disease; dose adjustment may be needed.
Overdose effects
Overdose: induce emesis (within 2-3 hours), keep patient in darkened room for 24 hours.
Storage conditions
Store below 30°C, away from light and moisture; keep out of reach of children.
Chemical structure
Methoxsalen