| PUVA
Therapy Background The full name for PUVA treatment is Oral Psoralen Photochemotherapy and this term describes the treatment. It consists of taking a medication called psoralen (pronounced soralen with a silent P) by mouth and subsequent exposure to UVA light (hence photo). The light and the chemical then interact to produce a therapeutic effect (hence photochemotherapy). The light involved in the interaction is a particular type of ultraviolet light called UVA. The acronym PUVA is derived from the P in psoralen and UVA. PUVA treatment is both old and new. Psoralens are naturally occurring chemicals found in the seeds of various plants. For more than 2,000 years herbal teas prepared from these seeds have been used in combination with sunlight, which contains UVA light, to treat skin disorders in India and the Middle East. However, the modern use of PUVA treatment only dates back about thirty years and it resulted from two important developments. First, pure psoralen was isolated from plants in 1947 and this permitted the use of precise doses of the medication. The pure psoralen was introduced in the USA in 1952 for treatment of a skin disorder called vitiligo and in combination with sunlight, it was a moderately successful treatment. The second major advance was the development of a high-intensity source of UVA radiation at Harvard in 1974. This permitted giving short and precise doses of UVA light so that sunlight, an unpredictable and unreliable source of UVA light, has been almost entirely eliminated in modern PUVA treatment. Development of a precise form of PUVA treatment resulted in an explosion of interest in determining how the treatment works and what disorders of the skin might benefit from the therapy. Several thousand articles have now been published in the scientific literature as a result of study of these questions in many centers throughout the world. Click here for our patient handout on PUVA Therapy PUVA Mechanism of Action All the answers are not yet known but PUVA therapy is beneficial in more than twenty different diseases and it appears to act via at least three different mechanisms: Prevention of Rapid Multiplication of Skin Cells In disease such as psoriasis, cells in the most superficial layer (the epidermis) of the skin are multiplying at many times the normal rate. PUVA treatment inhibits this multiplication by shutting down the production of DNA in cells. Killing of Cells in Skin A number of skin disorders appear to be produced by cells from the immune (defense) system of the body. These cells are either multiplying too rapidly or behaving in an abnormal manner. PUVA treatment selectively kills off these cells and fortunately, it can do this without producing any clinical evidence of harm to our normal immunity. Eczema, lichen planus, alopecia and mycosis fungoides, are a few of the diseases that appear to respond to PUVA therapy via this mechanism. Production of Increased Resistance to Sunlight PUVA therapy induces increased pigmentation in the skin and also increase the thick-ness of the epidermis. Both these effects diminish sensitivity to sunlight by decreasing the amount of ultraviolet light entering the deeper layers of the skin. This appears to be the mechanism whereby PUVA treatment is beneficial in disorders characterized by heightened sensitivity to sunlight, such as polymorphous light eruption and solar urticaria. The response of vitiligo to PUVA therapy is also partly due to this effect, but in addition PUVA is probably also affecting the function of immune cells in this disorder. Elements of PUVA Treatment There are two basic elements of PUVA treatment: UVA and psoralens UVA Light Sunlight consists of a spectrum of so-called electromagnetic radiation ranging from cosmic rays to radiowaves. Ultraviolet light consists of wavelengths shorter than visible light and is called ultraviolet because it begins next to the violet end of visible light. Visible light is light that we can see and it provides us with vision. Ultraviolet light is invisible to the human eye. Ultraviolet light is divided into UVA, UVB and UVC. UVC light is only of interest to astronauts since it is absorbed by ozone in the atmosphere and does not reach the surface of the earth. UVB light does reach earth and this waveband is responsible for producing a sunburn and a suntan when we are exposed to sunlight. Sunlamps mainly emit UVB light. UVA light is composed of the longest wavelengths in the ultraviolet spectrum. Under normal conditions UVA light from sunlight does not produce any noticeable change in skin. However, UVA light does have the property of being able to react with light-activated chemicals in the skin, so-called photosensitizing agents. These chemicals include some antibiotics, tranquilizers, diuretics and psoralens. If these chemicals are present in our skin when we are exposed to UVA light, redness like sunburn, and even blistering can occur. Psoralens These are a family of photosensitizing compounds that are activated by UVA light. Thus, if they are present in skin at the time of exposure to UVA light, they greatly increase the effect of the light on skin. This increased sensitivity is the key to the beneficial effect of PUVA treatment of skin disorders. It is important to emphasize that psoralens alone have no effect on the skin or skin disorders. Likewise, UVA light alone produces no noticeable change in the skin or beneficial effect on skin disorders. The psoralen most frequently used in treatment has the chemical name of methoxsalen and the U.S. trade name of Oxsoralen Ultra. PUVA Treatment The photochemotherapy process involves the ingestion of psoralen and then exposure to UVA light one hour later. The dose of psoralen you take is held constant and is determined by your weight. The interval between taking psoralen and being exposed to light is also held constant because peak levels of psoralen in the skin are usually reached between one and two hours after ingestion. For example, if you take your Oxsoralen capsules at 11am, you should aim to be treated at 12 noon and certainly before 1pm. Take the capsules with water or low-fat milk and avoid eating until after the treatment. The variable in the treatment is the dose of UVA light you are given. The initial dose is low and determined by either your past history of sunburning and suntanning or by testing your response to PUVA. The dose of UVA light is gradually increased in subsequent treatment as your tolerance to the treatment increases. The dose of UVA light is measured in joules per square centimeter, which is an amount of energy, and this is translated into a certain number of minutes of treatment. The output of the treatment units varies over time and different units emit different amounts of energy. Therefore, even if your dose of UVA light is constant, the time for your treatment will vary from day to day. Treatments will be required 2-4 times each week until your skin disease has cleared. Less frequent treatment is necessary to maintain a clear state. A Few Helpful Hints • If your skin disorder involves the scalp you have to help the light reach it. Short hair is obviously one answer. Hair bands and bobby pins should be used to hold hair off the face and neck. • Nail polish may be worn even if the fingernails and toenails are involved by your skin disorder. However, if the disorder affects the skin under the nail, do not paint your nails. • Scales on the skin tends to block UVA light from penetrating. Try to remove as much scale as possible before each treatment by soaking or applying an emollient or skin moisturizer. • Regular, punctual treatments are the key to success with PUVA therapy. Missed treatments simply delay a good response and sometime lead to failure of therapy. If you are having problems keeping appointments, discuss the matter with the physician so a fresh approach can be developed. Conclusion PUVA therapy has been the subject of more investigation than almost any other treatment used in dermatology, or for that matter, any treatment used in any field of medicine. The reason for this is that the treatment was largely developed in its present form in one center, Massachusetts General Hospital, and people there had the foresight to start a prospective study of the effects of the treatment over a long period. This study involves 1,600 patients treated with PUVA therapy, who were followed with yearly reports for over twenty years. This study has provided us with a wealth of precise information on the effect of the treatment. At this point in time, we can conclude from all this investigation that PUVA therapy continues to be successful, people do not become refractory to the treatment and the adverse effects are infrequent, well-characterized and controllable. Potential Short-Term Problems Caused by PUVA Therapy The immediate side-effects which arise during treatment are usually minor and easily managed. - Sunburn or skin redness - Nausea - Tanning and/or freckles - Dryness - Itching - Eye Damage (if eye protection not used correctly) Potential Long-Term Problems Caused by PUVA Therapy PUVA treatment, just like ultraviolet light in sunlight, can have cumulative effects on the skin and eyes. - Skin Cancer - Aging Changes including photoaging - Cataracts For this reason, it is especially important with long term use of PUVA (or UVB) phototherapy, to have a complete skin cancer screening by your general dermatologist at least once per year. If you are in need of a recommendation for a general dermatologist for skin cancer screening, we are happy to offer you contact information for several board certified dermatologists in the area. Furthermore, a baseline eye examination when beginning PUVA is important, with regular follow-up as indicated as well as compliance with 100% UV protective eyewear on treatment days. Male patients should wear an athletic support during treatment if their skin disorder does not involve the genital area because skin in this area is very sensitive to ultraviolet light. If your skin disorder does not involve the face, shield the face during treatment because facial skin already receives a heavy exposure to UV light and it is unwise to increase the exposure if not needed. Any new lump or bump on the skin should be brought to the attention of the physician. Our nursing staff can assist you with these details if questions or concerns arise. Skin Diseases and Disorders Responsive to PUVA Therapy More Common Diseases - Psoriasis - Eczema and Dermatitis - Vitiligo - Mycosis Fungoides (Cutaneous T-Cell Lymphoma) - Lichen Planus - Photodermatoses (sunlight sensitivity) - Pruritus (itch) of any cause Less Common Diseases - Eosinophilic pustular folliculitis - Granuloma annulare - Graft-versus-host Disease - Morphea - Parapsoriasis - Pityriasis lichenoides - Pityriasis rosea - Polycythemia vera - Scleroderma - Transient acantholytic dermatosis (Grovers Disease) - Urticaria (hives) |
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9:00 a.m. - 7:30 p.m. EST Dr. Warwick Morison • Dr. Elisabeth Richard, Johns Hopkins at Green Spring 10753 Falls Road, Suite 355 Lutherville, MD 21093 Tel: (410) 847-3700, Fax: (410) 847-3703 |