STORAGE: Methoxsalen lotion should be stored at 15 to 30 C (59 to 86 F)
- Methoxsalen lotion should be applied to the affected area 2 hr. before UV exposure every 3 to 7 days.
- It takes a few weeks for pigmentation to begin.
- Significant repigmentation may take 6 to 9 months of treatment and re-treatment may be necessary to retain the new pigment.
DRUG CLASS AND MECHANISM:
- Methoxsalen is a naturally occurring photoactive chemical found in the seeds of the Ammi majus (Umbelliferae) plant and in the roots of Heraclem candicans. It belongs to a group of compounds known as psoralens, or furocoumarins. Methoxsalen lotion is used for treating vitiligo (leucoderma). The exact mechanism of action of methoxsalen is not known.
- Methoxsalen has several biological actions that may be responsible for its medical effects. Methoxsalen is a photosensitizer that increases the reaction of skin cells to UVA. Some experts suggest that methoxsalen improves vitiligo by stimulating melanocytes (melanin forming skin cells) to move up the hair follicle and to repopulate the epidermis. Methoxsalen also combines with DNA in skin cells, leading to inhibition of DNA synthesis, cell division, and reduced formation of new skin cells. Administration of methoxsalen combined with UVA exposure causes cellular damage, leading to skin inflammation and erythema. The damaged skin heals after several days to weeks.
- The FDA approved methoxsalen lotion in December 1954.
REFERENCE: FDA Prescribing Information
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