methoxsalen (8MOP, Oxsoralen, Oxsoralen Ultra, Uvadex)

Dosing and uses of 8MOP, Oxsoralen (methoxsalen)

• Adult
• Pediatric

 

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