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PUVA Therapy (Photochemotherapy) (cont.)

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What are the advantages and disadvantages of PUVA?

The major advantage to PUVA is that it is an effective therapy that becomes active only at the site of exposure. It can be used to treat large areas of skin, and the fact that the drug is only activated in the presence of UV light implies that it may be less toxic than other therapies that require systemic administration and whose effects are not localized to just the skin.

Since PUVA must be administered under a physician's supervision, it requires repeated visits to the office or clinic. PUVA does not cure psoriasis so treatment may be required indefinitely.

How is PUVA therapy administered?

The psoralen medication is taken 45-60 minutes prior to the ultraviolet light exposure. The amount of the psoralen is based on the weight of the patient. The length of the exposure depends on the degree of the patient's pigmentation. Accordingly, the darker the patient, the longer the exposure time. Depending on the equipment used, the exposure may occur in a metal light box surrounding the patient with the bulbs that run vertically and are generally 48 inches long and resemble fluorescent bulbs. In newer boxes, there is an integrated light meter that enables the operator to administer the desired amount of energy with an automatic shut off after that dosage of light is achieved.

How many PUVA treatments are necessary?

There ought to be a significant improvement in the patient's skin disease after about 15 treatments. Treatments are given no sooner than 48 hours apart because the burn (if there is one) induced by PUVA is often delayed for as long as two days (unlike ordinary sunburns). Unless there is a problem, the amount of energy administered to the patient is increased appropriately at each visit depending on the patient's coloration. After about 30 treatments, a decision is made as to whether to continue treatments. PUVA is not always effective. If there is no improvement after these treatments, it is probably unlikely that continuing this form of treatment is worthwhile. On the other hand, if significant clearing has occurred, it is probably prudent to decrease the frequency of treatments in order to maintain the improvement. Since there is a relationship between the amount of light energy administered and the degree of photo-aging and the induction of skin cancers, it is wise to limit the light exposures as appropriate.

Medically Reviewed by a Doctor on 9/12/2017


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