Psoriasis Treatment Systemic Therapy
Patients with psoriasis involving more than 20% of the body surface or who are very uncomfortable should consider systemic therapy. Systemic therapy is complicated and best managed by a dermatologist. A rotational approach to therapy minimizes long-term toxic effects from any one therapy and allows effective long-term management.
Methotrexate is effective in unstable erythrodermic, generalized pustular psoriasis and extensive chronic plaque disease. It is effective for psoriatic arthritis and can be given orally, intramuscularly or subcutaneously in doses of 12.5 to 22.5 mg weekly. Close follow-up is needed; monitor complete blood cell count, liver function, and liver biopsy should be performed periodically. Beware of potentially life-threatening drug interactions with salicylates, many non-steroidal anti-inflammatory agents, trimethoprim sulfamethoxazole, penicillins, and others. Side effects include nausea, anorexia, fatigue, oral ulcerations, leukopenia, and thrombocytopenia, hepatic fibrosis or cirrhosis. Use caution in the elderly or patients with renal insufficiency.
Cyclosporine is best used for severe inflammatory psoriasis and better yet for acute control only. The typical dose is 2.5 to 5.0 mg/kg/day. Once control is achieved, the dose is slowly tapered. Close monitoring of blood pressure is needed, as well as complete blood count, creatinine, magnesium and cholesterol/triglyceride levels. Decrease dose if creatinine increases by 30% from baseline and beware of potentially life-threatening drug interactions. Side effects include hypertension and cumulative renal toxicity.
Acitretin, brand name Soriatane, is highly effective for generalized pustular and erythrodermic psoriasis, and moderately effective for palmoplantar psoriasis. An oral retinoid, acitretin is useful in combination with psoralen plus ultraviolet A and ultraviolet B. Start at 10 to 25 mg/day as a single dose.
Side effects are similar to those of isotretinoin and include teratogenicity, dry skin, sticky skin, myalgias, arthralgias, pseudotumor cerebri, depression, hair loss, hepatitis, pancreatitis, increased cholesterol/triglycerides.