Methoxsalen injection

Generic name: Methoxsalen

Drug class: Psoralens

Dosage form: Injectable solution (20 mcg/mL)

Root of administration: Intravenous (IV) injection

Dose: The dosage of methoxsalen injection is individualized based on the patient’s condition and response to treatment. It is administered as part of a procedure called photopheresis, which involves collecting white blood cells, treating them with methoxsalen, and exposing them to ultraviolet A (UVA) light before reinfusion into the patient. The specific dosing regimen, including frequency and duration, is determined by the healthcare provider.

Mechanism of action: Methoxsalen is a naturally occurring furanocoumarin that, upon activation by UVA light, forms covalent bonds with DNA, leading to the formation of monofunctional and bifunctional adducts. This interaction disrupts DNA function, inhibiting the proliferation of abnormal skin cells associated with conditions like cutaneous T-cell lymphoma (CTCL).

Drug usage cases:

• Treatment of skin lesions caused by cutaneous T-cell lymphoma (CTCL) in combination with UVA light therapy.
• Management of severe psoriasis when other treatments have been ineffective.
• Therapy for vitiligo to repigment depigmented skin areas.

Drug contraindications:

• Hypersensitivity to methoxsalen or other psoralens.
• Conditions causing increased sensitivity to light, such as lupus, porphyria, albinism, or xeroderma pigmentosum.
• Existing damage to the lenses of the eyes (e.g., cataracts, aphakia).
• Concurrent use of medications that may interact adversely with methoxsalen, such as certain diuretics or griseofulvin.

Side effects:

• Severe skin reactions, including redness, blistering, or peeling, especially after UVA exposure.
• Eye discomfort, including pain, swelling, or visual disturbances like blurred vision or seeing halos around lights.
• Systemic reactions such as fever, dizziness, or light-headedness.
• Skin aging effects, including thinning, wrinkling, or increased pigmentation.
• Potential increased risk of skin cancer with prolonged use.

Warnings:

• Increased photosensitivity: Patients must avoid direct sunlight and artificial UV light for at least 24 hours after treatment. Protective clothing and UVA-absorbing sunglasses are recommended during this period.
• Potential for cataract formation: Proper eye protection is essential during and after treatment to prevent lens damage.
• Regular monitoring: Periodic eye examinations and skin assessments are necessary to detect adverse effects early.
• Use in pregnancy and breastfeeding: Methoxsalen may harm an unborn baby. Effective contraception is advised during treatment. The safety of methoxsalen during breastfeeding is not established; consult a healthcare provider before use.

Use during pregnancy or breastfeeding: Methoxsalen is classified as a pregnancy category C drug, indicating potential risks to the fetus. Women who are pregnant or planning to become pregnant should discuss the risks and benefits of methoxsalen therapy with their healthcare provider. The safety of methoxsalen during breastfeeding is not well established; therefore, nursing mothers should consult their healthcare provider to determine the appropriateness of treatment during lactation.