Different types of coal tar are used to treat psoriasis-affected skin (shale, wood, coal, and distilled coal tar). Crude coal tar is one of the oldest psoriasis treatment options available. Many patients dislike using tar because it may be messy, smelly, and irritating. However, coal tar can provide significant benefit for patients.
Topical coal tar is available as a gel, cream, ointment, liquid bath solution, or shampoo. Coal tar can stain white hair, clothing, towels, and bedding; therefore, if you apply it before going to bed, use old pajamas and bedding. Coal tar can make the skin more sensitive to sunlight (photosensitizer), so be careful when exposing your skin to sunlight the day of coal tar application and carefully follow your doctor's instructions.
Psoriasis treatment centers may prescribe the Goeckerman regimen, whereby coal tar is applied before exposure to ultraviolet-B light to enable the ultraviolet rays to have a greater therapeutic effect on the skin. Coal tar is also effective when combined with topical corticosteroids.
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Anthralin
Anthralin (Psoriatec) has been widely used in the past as an effective treatment for psoriasis, but is now prescribed less frequently because, like tar, it is messy and stains clothing. Anthralin is able to stop psoriatic skin cell turnover, has an anti-inflammatory effect, and is most effective on chronic plaque-type psoriasis.
Anthralin is available in different concentrations, and therapy usually starts at a low potency with a gradual increase in the strength until the desired effect is obtained. Psoriasis treatment centers may use the lngram regimen, which involves applying anthralin prior to exposing the skin to ultraviolet.B light. The lngram regimen is generally used to treat moderate to severe psoriasis.
Another method of treating psoriasis with anthralin involves short contact anthralin therapy (SCAT) with higher potencies of anthralin applied to the skin, kept on for a short period of time, and then washed off. Application time is generally increased with subsequent applications until the psoriasis lesions have improved.
Unfortunately, anthralin is very messy and can discolor the skin, hair, and clothes. Newer preparations that stain less are now available. Anthralin can also be irritating to the skin, After application, it is advisable to wash the hands carefully. It is also important that patients do not expose anthralin to sensitive body areas and other untreated areas. If anthralin gets in the eyes, irritation can occur.
Vitamin D Analogue: Calcipotriol
Calcipotriol (Dovonex, Daivonex) is a derivative of vitamin D that became available in Canada in 1991 and was subsequently approved for U.S. distribution. Vitamin D can slow the rate at which psoriatic skin cells multiply. Calcipotriol also has anti-inflammatory properties. This topical treatment can be found in ointment, cream, or solution form. Calcipotriol comes in one strength (0.005 percent) and is available in 60 and 120 gram tubes (cream and ointment) and 30 milliliter and 60 milliliter scalp solutions. It is typically applied once or twice daily to the affected area, and improvements are usually seen within four to eight weeks.
Its major advantage over topical steroids is that it is a nonsteroidal therapy and therefore lacks many of the possible local side effects seen with steroids, such as skin thinning.
Although calcipotriol is well tolerated, it does have some drawbacks: It is slow to take effect and may cause irritation after application, particularly on the face and in skin folds. Another rare side effect is an increase in the levels of calcium in the bloodstream. The risk of increased calcium levels (hypercalcemia) is not seen if the maximum dose of 100 grams of calcipotriol per week is not exceeded in adults.
Calcipotriol might need to be used in combination with another topical therapy, phototherapy, or systemic medications in order to improve effectiveness. In 2001, a combination of calcipotriol and betamethasone dipropionate in the treatment of chronic plaque-type psoriasis was investigated and proved very effective. Because this new combination treatment includes a high-potency topical steroid, it is generally used for shorter periods, usually once a day for one month. After that time, another topical therapy can be substituted. Recently, a scalp gel containing calcipotriol and betamethasone dipropionate (Xamiol) has been successfully used in patients with scalp psoriasis.
It is important to note that calcipotriol is inactivated by salicylic acid, and lesions should not be pretreated with such keratolytics.
CaIcineurin lnhibitors (Nonsteroidal Therapies)
Calcineurin inhibitors (also known as topical immunomodulators or TIMs) are a new class of therapy that has been recently approved in the United States and Canada for the treatment of atopic dermatitis/eczema. Their use in treatment of psoriasis is being investigated. They work by inhibiting a key step in the activation of the T-lymphocyte, a cell in the immune system that is important in causing the skin changes of psoriasis and atopic dermatitis. There are two types of calcineurin inhibitors:
- tacrolimus (Protopic) (0.1 percent and 0.03 percent ointment)
- pimecrolimus (Elidel) (1 percent cream)
In the treatment of psoriasis, calcineurin inhibitors have had variable success. Initial clinical research failed to prove any benefit of topical tacrolimus or pimecrolimus in the treatment of psoriasis when applied to thick, scaly areas. There is evidence, however, that both these agents are effective when used for psoriasis on sites such as the face, groin, or armpits. These areas are particularly vulnerable to thinning of the skin when treated with topical steroids, which makes these new agents valuable additions as thinning of the skin has not been reported with either tacrolimus or pimecrolimus.
Since calcineurin inhibitors are nonsteroidal, they lack many of the side effects that can occur with topical steroids. The major side effect seen with tacrolimus or pimecrolimus is temporary burning on the skin. This tends to last for only a few minutes after application and generally resolves on its own within a week to ten days of therapy. Unfortunately, these agents are significantly more expensive than topical steroids.
Topical tacrolimus (Protopic) is currently available in ointment form as a 0.03-0.1 percent concentration (10 gram, 30 gram, 60 gram, and 100 gram tubes). Topical pimecrolimus (Elidel) is available in a 1 percent concentration cream (30 gram, 60 gram, and 100 gram tubes) only as a prescription.
Currently, there is ongoing clinical research to develop new bases such as creams, ointments, or gels. Pimecrolimus in pill form is currently being tested for use in chronic plaque-type psoriasis, and the initial clinical results have been very encouraging.
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Tazarotene (Tazorac)
Tazarotene is a topical vitamin A derivative available in a gel or cream. Tazarotene is effective predominantly in reducing scaling and thickness of plaques, but is less successful in reducing redness. When prescribed alone, the use of tazarotene is limited because many patients develop significant irritation at the site of application. Irritation can be reduced if tazarotene is used in combination with other topical steroids.
Tazarotene increases the skin's photosensitivity and has been successfully combined with both ultraviolet-B and narrowband ultraviolet-B therapy to provide more effective and rapid clearing of psoriasis versus either treatment alone. Tazarotene should not be used during pregnancy. To find out more, you can check out Psoriasis Coal Tar.