Blood concentrations and clinical effect of cyclosporin in psoriasis.

After approval by the Local Ethical Committee, 60 psoriatic patients, who participated in a previous pharmacokinetic study on cyclosporin A (CsA), gave their informed consent to continue to be studied during the maintenance treatment and at withdrawal. Peak concentration (Cmax), area under the concentration-time curve (AUC), bioavailability, elimination half-life, distribution volume, and body clearance were determined at monthly check-ups, along with blood pressure, psoriasis area, severity index (PASI), and creatinine serum levels. No modifications over time of treatment were observed on kinetic parameters. At the dose of 5 mg/kg in two daily administrations, a complete remission of the disease was observed after 1 month's treatment. At withdrawal, a worsening of PASI appeared when CsA daily dose reached 2 mg/kg b.w., the mean trough levels or AUC values being, respectively, 100 and 2,200 ng/ml.hr. There was a trend for patients with hypertension and nephrotoxicity at the end of the maintenance treatment to have higher trough, Cmax, and AUC values. Furthermore, blood pressure and serum creatinine tended to correlate better with AUC and Cmax, than with trough levels.