Psoriasis

Description

Alternative Names

Topical Medications

Topical medications are those applied only to the surface of the body. They come in the following forms:

• Ointments.
• Gels.
• Solutions.
• Creams.
• Sprays.
• Foams.
• Lotions.
• Shampoos.
• Occlusive tapes.

In general, topical treatments are the first line for mild to moderate psoriasis, but they may also be used alone or in combination with more powerful treatments for moderate to severe cases.

Topical Corticosteroids

Benefits. Corticosteroid topical treatments are the mainstays of psoriasis treatments in the US and are effective for most patients. They have multiple benefits, including the following:

• They reduce inflammation.
• They inhibit cell proliferation.
• They alleviate itching. (Sometimes itching can also be a side effect of the drug itself, however.)

Brands differ in potency and many are available in a number of formulations, including lotions, solutions, creams, emollient creams, ointments, gels, sprays, and on tape. Foam preparations are particularly making compliance much easier. Injections of certain steroids, such as triamcinolone, may help treat nail psoriasis.

They are also available in a wide range of potencies generally given as follows:

• Less potent drugs should be used for mild to moderate psoriasis.
• Higher-potency agents are indicated for more severe disease.

Topical Regimen. An example of a topical regimen that uses a single agent is as follows:

• A high-potency topical corticosteroid, such as halobetasol (Ultravate) used daily until the psoriasis plaque flattens out. (The transitional phase)
• After that the steroid is applied only on the weekends for maintenance.

Topical steroids generally have been administered twice a day. Studies are reporting, however, that certain agents can be applied effectively only once daily. Most studies have used high-potency steroids, but a 2001 study suggested that medium-potency agents, such as triamcinolone (Aureocort, Tri-Adcortl), may be equally beneficial as a once-daily treatment. In any case, however, corticosteroids used alone are effective in clearing psoriasis in only 4% to 36% of patients.

Combinations with other agents are often needed. For example, an effective, topical regimen uses the following combination for maintenance therapy:

• A high-potency steroid (e.g., halobetasol) on the weekend.
• The vitamin D3 topical agent, calcipotriene, twice daily on weekdays.

In one study, over three-quarters of patients with mild to moderate psoriasis remained in remission for at least six months with this regimen.

Side Effects. The more powerful a drug, the more effective it is. But it also has a higher risk for severe side effects. They can include the following:

• Burning.
• Irritation.
• Dryness.
• Acne.
• Thinning of the skin that may become shiny, fragile, and easily cut.
• Dilated blood vessels.
• Loss of skin color.

Corticosteroids should not be used during pregnancy or when nursing. The high-potency drugs carry a small risk for adrenal insufficiency, which is usually mild. If this occurs, the body loses its ability to produce natural steroid hormones for a period of time after the drug has been withdrawn, which can cause serious complications. With topical steroids, however, this event is uncommon and usually mild.

Loss of Effectiveness. In most cases, the patients become tolerant to the effects of the drugs, and they become ineffective. Some experts recommend using intermittent therapy (called weekend or pulse therapy), which involves applying a high-potency topical agent for three full days each week. In one study, intermittent treatment maintained improvement for six months in 60% of patients.

Coal Tar

Coal tar preparations have been used for psoriasis for about 100 years although its use has declined with the introduction of topical vitamin D3 analogs. Crude coal tar inhibits enzymes that contribute to psoriasis and helps prevent cell proliferation. Tar is often used in combination with other drugs and with ultraviolet B (UVB) phototherapy.

Side Effects. Preparations have the following drawbacks:

• The drug can cause sun sensitivity and increase the risk for sunburn for up to 24 hours after use.
• It has a strong smell.
• It can stain clothing.
• It irritates the skin.
• Ingesting the medication is life threatening. In such cases poison control should be called immediately.

Anthralin

Benefits. Anthralin (Dritho-Scalp, Drithocreme, Micanol), called dithranol in Europe, is a derivative of a traditional medication called chyrsarobin, in use since the early 1900s. Anthralin slows skin cell reproduction and can produce remissions that last for months. It is recommended only for chronic or inactive psoriasis, not for acute or inflamed eruptions.

Side Effects. As with tar, its use has also declined with introduction of the vitamin D topical analogs, but newer formulations, such as Micanol, have made its use more tolerable. Micanol (Psoriatec) is an anthralin formulated in micro-capsules, which dissolve and allow the drug to be delivered directly to the target skin areas. It is particularly useful for scalp psoriasis, and it is less apt to stain, as standard anthralin does.

• Skin irritation and burning. Anthralin should not be used on the face. Fair skinned people should generally avoid it. Triethanolamine (CuraStain) is a chemical that can neutralize anthralin and help reduce irritation from short-contact anthralin therapy. It should be applied a minute or two before washing off the anthralin. It is then reapplied after drying the skin.
• Brown staining. Older forms of anthralin, such as Drithocreme, can stain hair, fabrics, plastics, and other household products. Micanol does not stain household products if used with cool water. Washing stained items with hypochlorite (Clorox) detergents can help remove stains.
• Although topical preparations do not appear to affect areas other than the skin, people with kidney problems are advised to use anthralin with caution.

Application. Anthralin should be applied only to the psoriasis plaques. Many people use disposable gloves to avoid staining hands. The areas can usually be protected with dressings. Rub the cream in well and wipe off any excess. Wash off only with lukewarm water, not soap. (Using hot water will trigger the staining action.) A technique called short-contact anthralin therapy (SCAT), also called minute therapy, is useful for local areas of psoriasis. In such cases, anthralin is applied for only 10 minutes to an hour.

Topical Vitamin D3 Analogs

A topical form of vitamin D3, calcipotriene (Dovonex), called calcipotriol in Europe, is proving to be both safe and effective. It is now available in a foam preparation, which makes compliance even easier. Several other topical vitamin D3 analogs, showing promise include maxacalcitol (Oxarol), tacalcitol, and calcitriol (Silkis), the active form of vitamin D.

Benefits. Calcipotriene has the following benefits:

• It appears to help block skin cell proliferation.
• It enhances the maturity of keratinocytes (the impaired skin cell in psoriasis).
• It has anti-inflammatory properties.

It is at least as effective as moderate topical corticosteroids, short contact anthralin, and coal tar in improving mild to moderate plaque psoriasis. Unlike steroids, patients do not develop thinning of the skin or tolerance to the drug.

Combinations. Combinations with other topical and oral treatments may improve effectiveness.

• Calcipotriene is not as effective as the highest potency corticosteroids, but products or regimens that combine both agents are proving to be more effective than either agent alone. For example, an ointment that combines calcipotriene with betamethasone (Daivobet) may prove more effective than either agent alone.
• Studies also report success in some patients who use vitamin D ointments in combination with the phototherapy treatment.
• Combining vitamin D ointments with oral agents, notably methotrexate, acitretin, or cyclosporine, increases effectiveness and allows lower doses or either medication, thereby reducing side effects.

Side Effects. They include the following:

• Calcipotriene causes skin irritation in about 20% of patients, particularly on the face and in skin folds. In fact, it causes greater skin irritation than potent corticosteroids. Diluting the drug with petrolatum or applying topical corticosteroids to sensitive areas may prevent this problem.
• Although the drug appears to be safe and effective in children, there is some concern that it may lower levels of vitamin D to the extent that it could affect bone growth. More studies are needed to assess this effect.
• There have been some reports of hypercalcemia (excessive levels of calcium in the blood) in some people who apply it to large areas.

Topical Retinoids

Retinoids are vitamin A derivatives and are being used for various skin disorders. Tazarotene (Tazorac) is the first topical retinoid found to be effective for mild to moderate psoriasis. It is available in cream or gel from.

Benefits. Tazarotene benefits the targeted skin tissue without causing the adverse systemic effects of oral retinoids. Also unlike steroids, patients do not develop thinning of the skin or tolerance to the drug. Only a very small amount is needed on each lesion. It can be used on the scalp and nails, but it is not recommended for the genital areas or around the eyes. The gel should be used on only 20% of the body at anytime, the cream on up to 35%. (As a way of measuring, the palm of the hand is about 1% of the body surface.)

Side Effects. Tazarotene can cause dryness and irritation, including on normal skin. Applying zinc oxide around the treated area can protect the healthy skin. Using a moisturizer can help reduce dryness. At levels high enough to be effective for psoriasis, tazarotene can cause severe skin irritation. This agent, then, is usually used in combination with other treatments, therefore allowing a lower dose. Mixing the drug in equal amounts with petroleum jelly (Vaseline) initially and then gradually increasing the amount of tazarotene may help the skin areas become less sensitive. It should be noted that the skin can become very red while it is actually improving.

Vitamin A derivatives have been associated with birth defects, and the drug should not be used by women who are pregnant, who wish to conceive, or who are nursing.

Combinations. Combinations, such as with topical steroids or phototherapy, are more effective than the use of the agent alone. Unlike vitamin D3, phototherapy with either UVA or UVB inactivates this agent, although there is a higher risk for sunburn.

Salicylic Acid

Topical salicylic acid (the active ingredient in aspirin) is useful for removing scaly plaque and enhancing other agents. It should not be used to cover wide areas of the body, since it can cause nausea and ringing in the ears. Combinations with high potency steroids, such as mometasone furoate (Combisor), clobetasol propionate, and betamethasone, are proving to be very helpful. Only Combisor is available in the US.

Investigative Topical Agents

A number of topical agents are under investigation. One such agent, tacrolimus (Protopic), is an immunosuppressant that is proving to be useful in allergic skin disorders and is being studied for psoriasis. Studies have been mixed on its benefits, although new delivery methods may make it more effective. It may prove to be safe for sensitive areas, such as the face. Pimecrolimus (Elidel), a similar agent, is also being studied.