PUVA Therapy (Psoralen and Ultraviolet A Therapy)

PUVA Therapy Overview

PUVA is an acronym for psoralen and ultraviolet A. PUVA refers to the interaction of long wavelength ultraviolet light (320-400 nm) with a pharmaceutical molecule of plant origin, psoralen, producing a type of "photochemotherapy." PUVA is useful in treating a number of human diseases.

Psoralens are a family of plant chemicals that are able to absorb light in the ultraviolet A (UVA) spectrum (320 nm-400 nm). Once this absorption has occurred, these chemicals become activated and can react within the body in a number of ways. Without exposure to the correct wavelengths of light, psoralens are not biologically active. Although human tissues are relatively resistant to the effects of ultraviolet A light alone, this changes dramatically when psoralens are present. The most obvious change is a marked increase in ultraviolet A sensitivity manifested as burning of the skin (the equivalent of sunburn). It is hypothesized PUVA may work by inhibiting the production of the basic genetic material, DNA, and/or by damaging receptors of skin cells (epidermal cells) and particular immune cells (T-lymphocytes).

PUVA Therapy Types

Two forms of the psoralen molecule are currently medically useful: 8-methoxypsoralen (8-MOP) and 5-methoxypsoralen. 8-MOP is the only psoralen available in the United States by prescription. 8-MOP can be given orally or applied topically. The use of topical of 8-MOP is uncommon because of the high likelihood of severe sunburns using this technique. The oral dose of 8-MOP that is prescribed for each patient depends upon the individual's weight.

Medical Author:

Gary W. Cole, MD, FAAD

Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

PUVA Therapy Treatment»

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Glossary

PUVA Therapy Topic Guide