Pharmacodynamic monitoring of cyclosporin.

The efficacy of cyclosporin as an immunosuppressive agent is largely based on clinical indicators such as graft survival, rejection or nephrotoxicity. Therapeutic monitoring is necessary to evaluate the efficacy of cyclosporin therapy. The most widely used method for monitoring cyclosporin therapy is the measurement of predose through blood concentrations of the drug. The relationship of a single or multiple blood cyclosporin concentration to slowly evolving outcomes is difficult to establish. Some investigators have found a good correlation between cyclosporin trough concentrations on the one hand and cyclosporin toxicity and rejection on the other, but others have not. Therapeutic monitoring of cyclosporin may be enhanced using some biological assays for immunosuppression (pharmacodynamic monitoring) in addition to cyclosporin trough concentrations (pharmacokinetic monitoring). However, direct monitoring of the immune response to cyclosporin therapy using a clinically applicable biological assay is difficult. Some pharmacodynamic parameters have been suggested as biological markers in the clinical monitoring of cyclosporin.