[Determination of cyclosporine A using high-performance liquid chromatography]

Recent analytical possibilities of therapeutic drug monitoring (TDM) of cyclosporine A (CyA) both in solid organ transplanted patients and in patients with autoimmune diseases are described. The standard method for determination of CyA in blood is a validated HPLC method. HPLC methods were developed which make it possible to determine not only the parent drug, but also the main metabolites of CyA: AMI (M17), AM9 (M1), and AM4N (M21). Preparation of blood samples, their extractions and purifications are discussed. Chromatography is usually carried on C18 or CN columns by isocratic elution under high temperature (70 degrees C). CyD or CyC is used as the internal standard HPLC-MS method enables unambiguous identification of CyA metabolites after their separation on a chromatographic column and it is used mostly for research purposes only.