Methoxsalen Disease Interactions

The use of methoxsalen (a psoralen) with ultraviolet radiation (UVA) is contraindicated in patients with aphakia. The potential for retinal damage with PUVA (psoralen and UVA photochemotherapy) may be increased due to the absence of lenses.

The use of methoxsalen with ultraviolet radiation is contraindicated in patients with a history of photosensitive disease states. Methoxsalen is a potent photosensitizer that can induce severe burns and marked hyperpigmentation and aging of skin in susceptible patients or when used improperly. Diseases associated with photosensitivity include lupus erythematosus, porphyria cutanea tarda, erythropoietic protoporphyria, variegate porphyria, xeroderma pigmentosum, and albinism.

The use of methoxsalen (a psoralen) with ultraviolet radiation (UVA) is contraindicated in patients with melanoma, invasive squamous cell carcinomas, or a history of melanoma. PUVA (psoralen and UVA photochemotherapy) may be associated with increased risks of squamous cell carcinoma, basal cell carcinoma and melanoma. Methoxsalen markedly enhances skin reactivity to UVA, and exposure to sunlight and/or UVA can cause premature aging of the skin and skin cancer. If necessary, patients with a current or past history of multiple basal cell carcinomas or other nonmelanoma skin cancers may be treated with PUVA but should be carefully monitored. The usual restrictions concerning sun exposure before and after treatment as well as prescribed dosage must be followed closely.

Patients with cardiac disease may not be able to tolerate prolonged standing or exposure to heat stress required of treatment in a vertical UVA chamber. Therapy with methoxsalen, if used in patients with cardiac disease, may require special precautions.

Patients with hepatic insufficiency should be treated with caution since hepatic biotransformation is necessary for drug urinary excretion.

PUVA (psoralen and UVA photochemotherapy) may be associated with increased risks of squamous cell carcinoma, basal cell carcinoma and melanoma. Methoxsalen, a psoralen, markedly enhances skin reactivity to UVA radiation, and exposure to sunlight and/or UVA can cause premature aging of the skin and skin cancer. The total lifetime dose of UVA that can be safely administered has not been established. Therefore, PUVA should be given cautiously in patients with a history of x-ray or grenz ray therapy. Close monitoring for signs of carcinoma is recommended. The usual restrictions concerning sun exposure before and after treatment as well as prescribed dosage must be followed closely.

Patients presenting with a sunburn should not be treated with methoxsalen (a psoralen) and ultraviolet radiation (UVA), since it may be difficult to evaluate the response of these patients to therapy. The mild, transient erythema normally seen 24 to 48 hours after PUVA (psoralen and UVA photochemotherapy) indicates a therapeutic interaction occurring between the psoralen and UVA but may be masked by a sunburn. Patients generally should avoid sunbathing for at least 24 hours prior to methoxsalen administration and UVA exposure. The usual restrictions concerning sun exposure after treatment and the prescribed dosage should also be followed closely to avoid severe burns and other phototoxic reactions.