Psoriasis

Systemic Treatment

For more severe forms of psoriasis, doctors sometimes prescribe medicines that are taken internally by pill or injection. This is called systemic treatment. 

• Retinoids--A retinoid, such as acitretin (Soriatane), is a compound with vitamin A-like properties that may be prescribed for severe cases of psoriasis that do not respond to other therapies. Because this treatment also may 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.

• Methotrexate--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 clotenhancing platelets.

• Cyclosporine--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.

• 6-Thioguanine--This drug is nearly as effective as methotrexate and cyclosporine. It has fewer side effects, but there is a greater likelihood of anemia. This drug must also be avoided by pregnant women and by women who are planning to become pregnant, because it may cause birth defects.

• Hydroxyurea (Hydrea)--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.

• Alefacept (Amevive)--This is the first biologic drug approved specifically to treat moderate to severe plaque psoriasis. It is administered by a doctor, who injects the drug once a week for 12 weeks. The drug is then stopped for a period of time while changes in the skin are observed and a decision is made regarding the need or further treatment. Because alefacept suppresses the immune system, the skin often improves, but there is also an increased risk of infection or other problems, possibly including cancer.

• Etanercept (Enbrel)--This drug is an approved treatment for psoriatic arthritis where the joints swell and become inflamed. Like alefacept, it is a biologic response modifier, which after injection blocks interactions between certain cells in the immune system. Etanercept limits the action of a specific protein that is overproduced in the lubricating fluid of the joints and surrounding tissues, causing inflammation. Because this same protein is overproduced in the skin of people with psoriatic arthritis, patients receiving etanercept also may notice an improvement in their skin.

• Antibiotics--These medications are not indicated in routine treatment of psoriasis. However, antibiotics may be employed when an infection, such as that caused by the bacteria Streptococcus, triggers an outbreak of psoriasis, as in certain cases of guttate psoriasis.