methoxsalen (8MOP, Oxsoralen, Oxsoralen Ultra, Uvadex)
Classes: Antifungals, Topical; Antipsoriatics, Systemic; Antipsoriatics, Topical; Psoralens
Dosing and uses of 8MOP, Oxsoralen (methoxsalen)
Adult dosage forms and strengths
capsule
- 10mg
soft capsule
- 10mg
lotion
- 1%
solution for injection
- 20mcg/mL (10mL vial)
Vitiligo
PO
- 20 mg with milk or food 2-4 hr before UV exposure
- UV exposure: initial 15-25 min (based on skin color); add 5 min on each subsequent exposure (qOD) up to erythema/tenderness tolerance
TopicaL
- Apply 1% lotion to affected area 2 hr before UV exposure q3-7 days
Psoriasis
Take PO with milk or food 2 hr before UVA exposure (qOD)
Body weight guidelines
- <30 kg: 10 mg
- 30-50 kg: 20 mg
- 51-65 kg: 30 mg
- 66-80 kg: 40 mg
- 81-90 kg: 50 mg
- 91-115 kg: 60 mg
- >115 kg: 70 mg
May increase dose by 10 mg after 15 therapy sessions (do not increase any more than this)
Cutaneous T-Cell Lymphoma
PO
- Take PO with milk or food 2 hr before UVA exposure
- Initial dose 0.6 mg/kg
- If serum concentration <50 ng/mL, administer initial dose + 10 mg after 24 hr
ParenteraL
- Inject 200 mcg (10 mL) into photoactivation bag of UVAR photopheresis system
- Treatment on two consecutive days q 4 weeks for a min. of 7 treatment cycles
Systemic Sclerosis (Orphan)
Uvadex indicated in conjunction with the UVAR photopheresis to treat diffuse systemic sclerosis
Orphan indication sponsor
- Therakos, Inc; Oaklands Corporate Center; 437 Creamery Way; Exton, PA 19341"
Cardiac Allograft Rejection (Orphan)
Uvadex designated orphan indication for prevention of acute rejection of cardiac allografts
Orphan indication sponsor
- Therakos, Inc; Oaklands Corporate Center; 437 Creamery Way; Exton, PA 19341"
Graft Versus Host Disease (Orphan)
For use in conjunction with the UVAR photopheresis system to treat GVHd
Orphan indication sponsor
- Therakos, Inc; Oaklands Corporate Center, 437 Creamery Way; Exton, PA 19341
Other Information
See Manufacturer label for complete UVA therapy information
Pediatric dosage forms and strengths
<12 years old: safety and efficacy not established
8MOP, Oxsoralen (methoxsalen) adverse (side) effects
All Patients
Mild-moderate erythema x 24-48 hrs
1-10%
Nausea
Pruritis
Frequency not defined
Edema
Dizziness
Headache
Malaise
Depression
Hypopigmentation
Bullae formation
Rash
Herpes simplex
Uritcaria
GI disturbances
Leg cramps
Hypotension
Extension of psoriasis
Postmarketing Reports
Rash
Allergic reaction
Pyrexia
Nausea
Dysgeusia
Warnings
Black box warnings
Injection
- Should be prescribed only by physicians who have competence in both the diagnosis and treatment of cutaneous T-cell lymphoma and the UVAR Photopheresis System
PO
- Use with UV radiation should be done only by physicians competent in photochemistry and in the diagnosis and treatment of psoriasis and vitiligo
- Reserve photochemotherapy for patients with severe, recalcitrant, disabling psoriasis unresponsive to other therapy
- Risks include ocular damage, aging of the skin, and skin cancer
- Do not interchange Oxsoralen-Ultra (Methoxsalen Soft Gelatin Capsules) with Oxsoralen or 8-MOP (Methoxsalen Hard Gelatin Capsules), as Oxsoralen-Ultra has a greater bioavailability and earlier photosensitization
Topical lotion
- Potent drug capable of producing severe burns if used improperly
- Should be applied only by a healthcare provider under controlled conditions
Contraindications
Hypersensitivity to psoralen compounds
Photosensitive disease states (SLE, etc.), history of melanoma, squamous cell carcinoma (SCC), aphakia
Cautions
Dosages of hard and soft capsules are NOT interchangeable
Tests prior to Tx and then q6-12mth: ophthalmologic exam, CBC, ANA, LFTs, RFTs
Overdose &/or overexposure could lead to serious burns from UVA or sunlight
Use appropriate shielding of eyes and unaffected skin during Tx
Increased risk of SCC, basal cell carcinoma (esp. if history of radiation Tx or arsenic Tx)
Wear UVA-absorbing sunglasses for 24 hr post-Tx to avoid cataract formation
Avoid sun exposure 8 hr post-Tx
Hepatic dz (hepatic metabolism), cardiac dz (heat stress)
Caution with concomitant photosensitizing agents
Do not sunbathe for 24 hr prior to Tx & for 48 hr post-Tx
Pregnancy and lactation
Pregnancy category: C
Lactation: not known whether excreted in breast milk; use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of 8MOP, Oxsoralen (methoxsalen)
Half-Life: 0.75-2.4 hr
Onset: 1-2 hr
Duration: 3-8 hr
Peak Plasma:
Time: 3 hr (conventional cap); 1.8 hr (liquid-filled cap)
Concentration: liquid-filled cap 2-3 x more than conventional cap
Other Information
Bioavailability: variable; enhanced by food
Protein Bound: 75-91%
Metabolism: hepatic
Metabolites: 8-hydroxypsoralen; glucuronide & sulfate conjugates
Excretion: urine
Mechanism of action
Photosensitizer; preferentially taken up by epidermal cells and binds to DNA, making it more susceptible to ultraviolet radiation damage
8-methoxypsoralen - photoactive derivative of Ammi majus and Heraclem candicans plants