Topical Preparations

Considered the first line of defense in psoriasis treatment because they tend to produce fewer side effects; topical preparations are applied directly to the affected skin or plaques. Several topical preparations, which include medications as well as moisturizers and scale removers, are used to treat psoriasis. These preparations are available over-the-counter and by prescription.

Topical Medications (FDA approved)
Mild to moderate psoriasis is frequently treated with topical medications. When topicals are not effective alone, they may be combined with systemic therapy or phototherapy. The topical medications that are approved by the U.S. Food and Drug Administration (FDA) for treatment of psoriasis are:

• Anthralin

• Coal tar

• Corticosteriods

• Retinoid: Tazarotene

• Vitamin D₃: Calcipotriene

Anthralin
Anthralin has been used to treat psoriasis for more than 100 years and is effective on plaque and guttate forms of psoriasis. Newer preparations and treatment methods minimize the traditional side effects of skin irritation and staining. In more severe psoriasis, anthralin may be used with ultraviolet light.

How it works: It is believed to act on psoriatic lesions by normalizing the growth rate of skin cells (keratinocytes), which decreases the skin’s rapid growth rate and reduces inflammation.

Coal Tar
One of the oldest treatments for psoriasis, coal tar is effective for mild to moderate plaque psoriasis, and new formulations show promise in treating moderate to severe plaque psoriasis. Tar shampoos are effective for scalp psoriasis.

Coal tar comes in numerous preparations, and some of these are available over-the-counter. These different formulations are used to treat scaling, inflammation and itching. One preparation is added to bath water. As the patient soaks, the tar helps to slow down or stop the formation of scale as well as soften thickened lesions.

Best results are typically seen when use is supervised by a dermatologist. While effective, patients often prefer other topical medications because coal tar has an unpleasant odor and can stain.

In severe psoriasis, coal tar may be combined with ultraviolet (UV) light therapy. This combination therapy, known as the Goeckerman Treatment, has been shown to clear psoriasis in many patients in about 3 to 4 weeks. To receive treatment, patients must go to specialized centers for daily therapy.

How it works: It is believed that coal tar decreases the rapid growth of the skin cells that cause plaques.

Corticosteroids
Corticosteriods, also known as steroids and glucocorticosteriods, remain the most frequently prescribed treatment for mild to moderate psoriasis. They are very effective in reducing inflammation, itch and the rapid growth rate of skin cells. Topical corticosteroids vary in potency—from extremely mild to very strong—and come in several forms, including lotions and ointments. While quite effective, topical corticosteroids are usually prescribed for a select purpose for a limited period of time due to potential side effects. They are frequently used in combination with other agents.

How it works: Corticosteroids decrease the rate at which skin cells grow and reduce inflammation.

Retinoid: Tazarotene
Tazarotene is a man-made retinoid (vitamin A derivative) approved for treatment of mild to moderate plaque psoriasis. It has also been reported to be effective in treating psoriasis of the nails. Available by prescription only, tazarotene comes in cream and gel form. Local skin irritation is a common side effect. When used in combination with topical corticosteroids, the effects of tazarotene are enhanced, skin irritation is decreased and some of the side effects from the corticosteroids are reduced. Tazarotene is not recommended for use in areas where skin folds occur due to possible skin irritation. Although the possibility of birth defects is much lower for topical retinoids than for the systemic forms, women who are pregnant or who may become pregnant should use topical retinoids only under close medical supervision.

How it works: Retinoids normalize DNA activity in skin cells, which decreases the rapid growth of skin cells.

Vitamin D₃: Calcipotriene
Calcipotriene is a man-made form of vitamin D approved for the treatment of mild to moderate plaque psoriasis. It may be combined with other topical agents or with phototherapy. Using caclipotriene and topical corticosteroids together produces fewer side effects than treating with either agent alone. However, knowledge of how different topicals interact with calcipotiene is required when calcipotriene is used in combination therapy because several topicals, including salicylic acid, inactivate calcipotriene. Calcipotriene is not the same as the vitamin D that one buys in a drug or health-food store; that vitamin D is of no value in treating psoriasis.

How it works: Is thought to slow down the rate of skin cell growth and reduce skin inflammation.

Topical Medications in Clinical Trials
Research shows that 2 topical medications, pimecrolimus and tacrolimus, may be effective in treating psoriasis. These 2 medications are FDA approved for treating eczema. In clinical trials, pimecrolimus and tacrolimus are showing much promise in treating inverse psoriasis with little skin irritation.

Both pimecrolimus and tacrolimus are topical immunomodulators (TIMs). When applied to the skin, they exert a powerful anti-inflammatory effect. Tacrolimus can be safely applied to the eyelids and other areas around the eye—where topical corticosteroids must be used with caution. Side effects tend to be mild and include minor itching and a sensation of warmth after application.

How they work: TIMs interfere with the activation of T cells, a type of white blood cell responsible for triggering immune responses that contribute to the development of psoriasis.

Moisturizers and Scale Removers
These products come in several forms, including creams, gels, lotions and shampoos. By themselves, they do not control psoriasis; rather, they help to lock in water and soften or remove scale, which allows topical medications to penetrate more deeply. These topical products may also reduce the redness and itching by keeping skin lubricated.

Salicylic acid is often used to effectively remove scale. It is available both by prescription and over-the-counter and comes in many forms, including lotion, gel, soap and shampoo. Potential side effects include skin irritation, a possible worsening of psoriasis and salicylism, a toxic syndrome that causes ringing in the ears, upset stomach and vomiting.

Reference:
Gribetz, C. et al. “Clearing Psoriasis: A New Era of Optimism.” Contemporary Dermatology 2003: Vol. 1, No. 1: 1-8.

An educational program brought to you by the American Academy of Dermatology.

For an overview, visit the AAD pamphlet Psoriasis and Psoriatic Arthritis.

Supported by an educational donation provided by Amgen and Wyeth.