Long-term low-dose cyclosporine therapy for severe psoriasis: effects on renal function and structure.
BACKGROUND: The effectiveness of cyclosporine in the treatment of severe psoriasis is well known. OBJECTIVE: We evaluated the efficacy and toxicity of systemic cyclosporine in patients with severe psoriasis, observing short-term (12 weeks) and long-term (3 to 5 years) effects. METHODS: To further elucidate efficacy and safety, 42 patients with severe psoriasis were treated initially with cyclosporine 5 to 6 mg/kg per day for 12 weeks. A subset of 14 patients continued maintenance treatment for 3.5 years to study the long-term effects of cyclosporine on renal function and structure. Renal biopsies were performed after 2.5 years and 3.5 years of treatment. Renal histologic findings were correlated with renal function. RESULTS: By weeks 8 and 12, 64% (n = 27) and 86% (n = 36) of patients, respectively, were rated clear or almost clear of the psoriasis. However, a subpopulation of 15 patients did not respond to 5 mg/kg daily but improved when the dose was increased to 6 mg/kg daily. Clearance or near clearance was achieved in 67% of this subpopulation after 4 weeks. For the 29 patients whose glomerular filtration rate (GFR) was measured, mean GFR fell by 7% from baseline to week 4 (p < 0.05). This change was reversible when dosage was reduced by 1 mg/kg per day in each of these patients. Patients older than 45 years of age experienced significant elevation of mean diastolic blood pressure and had reduced GFR and increased serum creatinine. After 2.5 years, of the 14 patients who continued maintenance treatment, two had biopsy specimens that showed moderate interstitial fibrosis and tubular atrophy. The remainder showed only minimal to mild structural damage. After 3.5 years of cyclosporine treatment, repeat renal biopsy specimens revealed slight increases in structural changes in nine subjects. These changes correlated with increasing age and drug-induced hypertension. CONCLUSION: We conclude that 5 mg/kg of cyclosporine daily is usually an effective initial dose for psoriasis. Patients who do not respond will often benefit from elevation of the dose to 6 mg/kg daily. Older patients experience cyclosporine-induced hypertension and changes in renal function and structure more frequently than do younger patients.