What is Psoriasis
Psoriasis is a skin condition commonly found on the elbows and knees, where it produces red scaly elevated plaques. It is non-contagious, affects all ages and sexes, and is a challenge to treat. It is not fully understood but seems to be an autoimmune disease.
What causes Psoriasis?
Initial outbreaks are sometimes caused by injury, but stress (physical and mental) can also trigger it. Heredity is a major factor, and genes linked to the disease have been identified. Flare-ups have been linked to infections, stress, dry skin, alcohol consumption and obesity. Some medications (beta blockers, lithium) may also trigger an outbreak.
Three options exist: topical treatments, photo treatments and systemic treatments. Topical treatments are applied to the skin; photo treatments expose the affected areas of the skin to specific light, and systemic treatments involve drugs by mouth or injection. Note that psoriasis can often become resistant to treatment, that results are very patient specific, and that they may sometimes worsen the condition.
Numerous strengths exist, ranging from 1 % hydrocortisone (an inexpensive over-the-counter corticosteroid) to those only available by prescription (e.g. Clobetasol). These steroids suppress the immune system, reducing inflammation. It is important to coordinate your treament with a doctor, since side-effects (thinning of skin, resistance) exist and can cause problems if not monitored.
(Retinoids are synthetic forms of vitamin A.) Less irritating, but slower acting then Steroids; can cause birth defects, so women of childbearing age must take measures to prevent pregnancies.
(Dovonex is a synthetic form of vitamin D3.) Works by controlling the turnover of skin cells; can have severe side effects (some countries require blood testing while using this drug). Should not be used on face or folds; can cause skin irritation or facial psoriasis.
A peeling agent, which reduces scaling of the skin. Often combined with topical corticosteroids.
Coal Tar, Bath Solutions, Moisturizers
All are soothing to varying degrees; their effectiveness seems to depend upon the patient. None will cure psoriasis.
Sunlight: Sunlight contains ultraviolet (UV) light which, when absorbed into the skin, causes activated T cells in the skin to die, reducing inflammation and slowing down the turnover of skin cells that cause scaling. Daily, short, nonburning exposure to sunlight clears or improves psoriasis in many people.
Ultraviolet B (UVB) Phototherapy
- Broadband UVB can be used for a few small lesions, to treat widespread psoriasis, or for lesions that resist topical treatment. Some patients use UVB light boxes at home under a doctor’s guidance.
- Narrowband UVB (NUVB) emits only the part of the ultraviolet light that is most helpful for psoriasis. NUVB treatment is thus in a way superior to broadband UVB, but it can cause more severe and longer lasting burns than broadband treatment.
Ultraviolet A (UVA) phototherapy/Psoralen and Ultraviolet A Phototherapy (PUVA)
Sunlight: Sunlight contains ultraviolet (UV) light which, when absorbed into the skin, causes activated T cells in the skin to die, reducingUVA has a longer wavelength than UVB, thus penetrating deeper into the skin than UVB. In order to make the skin more sensitive to UVA, one often administers a medication called psoralen. The combination treatment is then called PUVA. PUVA is normally used when more than 10 percent of the skin is affected or when the disease interferes with a person’s occupation (for example, when a teacher’s face or a salesperson’s hands are involved). A drawback of the therapy is the increase in light sensitivity, so care must be taken to avoid sunburns, and the eyes must be protected with UVA-absorbing glasses. PUVA treatment taken two to three times a week clear psoriasis more consistently and in fewer treatments and UVB.
Tunable Light Systems
In these new systems, NUVB is transmitted through a fiber optic line directly to the psoriatic lesion. Since normal skin is not exposed, high intensity may be used, resulting in a faster treatment.
Light therapy combined with other topical treatments
Studies have shown that a retinoid adds to the effectiveness of UV light for psoriasis. For this reason, UVB or PUVA may be combined with retinoids and other treatments.
Dr. Voss actually did research on the effects of Methotexate on psoriasis and published, along with her husband (a physicist), a paper on the subject. Like cyclosporine, methotrexate slows cell turnover by suppressing the immune system. It can be taken by pill or injection. Patients taking methotrexate must be closely monitored because it can cause liver damage and/or decrease the production of oxygen-carrying red blood cells, infection-fighting white blood cells, and clot-enhancing platelets. As a precaution, doctors do not prescribe the drug for people who have had liver disease or anemia (an illness characterized by weakness or tiredness due to a reduction in the number or volume of red blood cells that carry oxygen to the tissues). It is sometimes combined with PUVA or UVB treatments. Methotrexate should not be used by pregnant women, or by women who are planning to get pregnant, because it may cause birth defects.
A retinoid is artificial vitamin A that may be prescribed for severe cases of psoriasis that do not respond to other therapies. Because this treatment may also cause birth defects, women must protect themselves from pregnancy beginning 1 month before through 3 years after treatment with acitretin. Most patients experience a recurrence of psoriasis after these products are discontinued. Common side effects include dry lips, hands and feet. Use of retinoids in conjunction with UV treatments has been found to be very effective for some people.
Taken orally, cyclosporine acts by suppressing the immune system to slow the rapid turnover of skin cells. It may provide quick relief of symptoms, but the improvement stops when treatment is discontinued. The best candidates for this therapy are those with severe psoriasis who have not responded to, or cannot tolerate, other systemic therapies. Its rapid onset of action is helpful in avoiding hospitalization of patients whose psoriasis is rapidly progressing. Cyclosporine may impair kidney function or cause high blood pressure (hypertension). Therefore, patients must be carefully monitored by a doctor. Also, cyclosporine is not recommended for patients who have a weak immune system or those who have had skin cancers as a result of PUVA treatments in the past. It should not be given with phototherapy.
Compared with methotrexate and cyclosporine, hydroxyurea is somewhat less effective. It is sometimes combined with PUVA or UVB treatments. Possible side effects include anemia and a decrease in white blood cells and platelets. Like methotrexate and retinoids, hydroxyurea must be avoided by pregnant women or those who are planning to become pregnant, because it may cause birth defects. This is an extremely potent drug that was originally used to treat cancer patients in combination with chemotherapy.
One of the newest classes of treatment for psoriasis are drugs collectively known as “biologics.” These in general are types of manufactured proteins that attempt to impact the actual immune pathway of psoriasis, instead of affected skin cells. However, unlike other immunosuppression therapies such as Methotrexate, biologics try to narrowly focus on the one aspect of the immune function causing the psoriasis instead of broad immune system suppression. These drugs have only recently begun to receive approval by the FDA, and their long-term impact on immune function is currently unknown. Examples of biologics would be compounds such as Amevive®, etanercept (Enbrel®), Humira®, infliximab (Remicade®) and Raptiva.
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