Background: Cyclosporin is an effective treatment for severe plaque psoriasis. Unfortunately, its use may be limited by time- and dose-related nephrotoxicity. Serum trough levels may be useful for monitoring the risk of nephrotoxicity.
Objectives: To determine whether monitoring of trough levels is necessary in psoriasis patients undergoing short-term treatment with cyclosporin.
Methods: A computerized and manual literature search identified studies on adults with plaque-type psoriasis treated with cyclosporin < or = 5 mg kg-1 daily, in which trough levels were measured in whole blood. Number of patients, treatment duration, formulation and dosage, renal function tests and trough levels were extracted. The association between renal function and trough levels was investigated. Additionally, in a randomized controlled trial on cyclosporin vs. methotrexate in moderate to severe psoriasis, cyclosporin trough levels were measured frequently in 20 patients during 12 weeks of treatment. The Pearson correlation coefficient between serum creatinine and cyclosporin trough levels was calculated.
Results: Fifty-six articles were found concerning cyclosporin trough level measurements in psoriasis patients, of which eight were analysed. Many studies were excluded due to inappropriate cyclosporin dosages used. As data were heterogeneous and lacked various key parameters, a correlation study and a meta-analysis could not be performed. Instead, a quantitative description of the literature was given. No high mean trough levels or elevations of serum creatinine were described. In our clinical study, all the mean trough levels in 17 patients treated with cyclosporin 3 mg kg-1 daily were within the therapeutic range (< 200 ng mL-1). Elevated trough levels were found in two of three patients treated with cyclosporin 3-5 mg kg-1 daily. No signs of renal dysfunction were seen.
Conclusions: The literature does not provide a definitive answer on whether monitoring cyclosporin trough levels in patients with psoriasis should be standard practice. Our own data show no need for cyclosporin trough level monitoring during short-term treatment with cyclosporin 3 mg kg-1 daily. However, when cyclosporin doses are > 3 mg kg-1 daily, monitoring may be indicated.