Quality assurance programs for immunosuppressive drugs: cyclosporine and beyond.

Monitoring blood cyclosporine concentrations as a guide to therapy has become established as a useful guide for optimal prescription of the drug. Quality assurance programs for external assessment of cyclosporine measurements have helped to clarify many of the methodological problems associated with measurement of the drug. A number of new immunosuppressive agents are in development and, although experience in their routine monitoring in clinical practice is still at an early stage, some observations regarding external assessment of their measurement can be made. This article summarizes the lessons to be drawn from the experience of cyclosporine quality assurance programmes and suggests some areas in which these lessons could be applied in the field of new immunosuppressive drugs.