Methoxsalen (Topical)

Medically reviewed by Drugs.com. Last updated on Dec 25, 2023.

Pronunciation

(meth OKS a len)

Index Terms

• Ammoidin
• Methoxypsoralen

Pharmacologic Category

• Psoralen

Pharmacology

Bonds covalently to pyrimidine bases in DNA, inhibits the synthesis of DNA, and suppresses cell division. The augmented sunburn reaction involves excitation of the methoxsalen molecule by radiation in the long-wave ultraviolet light (UVA), resulting in transference of energy to the methoxsalen molecule producing an excited state (“triplet electronic state”). The molecule, in this “triplet state,” then reacts with cutaneous DNA. Causes photosensitization which leads to cell inquiry and an inflammatory reaction. The erythematous reaction is followed over days to weeks by repair which manifests as higher melanization of the epidermis and thickening with the stratum corneum. Frequency is regulated by the erythema by healthcare provider response.

Use: Labeled Indications

Repigmentation of idiopathic vitiligo

Contraindications

Hypersensitivity to methoxsalen (psoralens) or any component of the formulation; diseases associated with photosensitivity (eg, albinism, lupus erythematosus, porphyria [cutanea tarda, erythropoietic and variegate], xeroderma pigmentosum); invasive skin cancer; melanoma or history of melanoma; children <12 years of age

Dosing: Adult

Note: Oxsoralen has been discontinued in the US for more than 1 year.

Note: Refer to treatment protocols for UVA exposure guidelines.

Vitiligo: Topical: Lotion is applied by healthcare provider prior to UVA light exposure, usually no more than once weekly; frequency is determined by erythema response

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Note: Oxsoralen has been discontinued in the US for more than 1 year.

Vitiligo: Topical: Children ≥12 years: Refer to adult dosing.

Administration

Hands and fingers of person applying the lotion should be protected to prevent possible photosensitization and/or burns.

Drug Interactions

There are no known significant interactions.

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.

Frequency not defined.

Dermatologic: Burning sensation of skin, erythema, skin blister, skin irritation

Warnings/Precautions

Concerns related to adverse effects:

• Burns: Serious burns may occur from ultraviolet radiation or sunlight (even if exposed through glass) if recommended exposure schedule is exceeded and/or protective clothing/sunscreen is not used

• Cataracts: Methoxsalen concentrates in the lens; eyes should be shielded from direct and indirect sunlight for 24 hours to prevent possible formation of cataracts. The risk associated with topical therapy is likely to be lower due to reduced systemic exposure to methoxsalen.

• Photosensitivity: Avoid sun (including sun lamp) exposure for 8 hours after methoxsalen exposure. Protective clothing, eyewear, and sunscreen (do not apply sunscreen to psoriatic areas) should be used for several days after combined methoxsalen/UVA therapy. Do not use in sunburned patients until they have fully recovered; pre-existing sunburn may obscure evaluation of response; advise patients to avoid sunbathing for 24 hours prior to treatment and for several days after treatment. Use extreme caution in patients who have significant exposure to the sun through their occupations.

• Skin cancer: Systemic therapy increases risk of skin cancer (basal cell, melanoma and squamous cell); has not been reported with topical treatment; use caution with fair skin or prior exposure to coal tar/UV treatment, ionizing radiation, or arsenic.

Disease-related concerns:

• Basal cell carcinoma: Use with caution in patients with multiple basal cell carcinomas or a history of basal cell carcinoma; observe closely.

Concurrent drug therapy issues:

• Photosensitizing agents: Use caution with other (systemic or topical) photosensitizing drugs (eg, thiazides, tetracyclines, fluoroquinolones, phenothiazines, sulfonamides, anthralin, coal tar preparations).

Special populations:

• Pediatric: Use is contraindicated in children <12 years of age; safety and efficacy have not been established. The long-term effects of treatment (including potential cataract formation, skin cancer development, and premature skin aging) are unknown in children.

Other warnings/precautions:

• Experienced physician: Should be administered under the supervision of an experienced physician with special competence in the diagnosis and treatment of dermatologic diseases. Product should not be dispensed to the patient.

Pregnancy Risk Factor C Pregnancy Considerations

Animal reproduction studies have not been conducted with topical methoxsalen.

Patient Education

What is this drug used for?

• It is used to treat white patches on your skin (vitiligo).

• It is used with light therapy.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Itching

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Severe skin irritation

• Sunburn

• Skin sores

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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