Cyclosporine A is a cyclic polypeptide with immunosuppressive activity. It is used clinically for antirejection in various organ or bone marrow transplant patients and can treat autoimmune diseases. Cyclosporine A is mainly metabolized in the gastrointestinal tract by the liver drug enzyme CYP3 A family

and more than 30 metabolites are obtained

which are excreted through bile. The primary metabolites AM1

AM9 and AM4 N have significant immunosuppressive activity and hepatorenal toxicity. The total concentration of cyclosporine A and its metabolites could be detected simultaneously by immunoassay

while high performance liquid chromatography can be used to detect the concentration. The physiological or pathological status of the patient also affects the distribution of cyclosporine A and its metabolites in vivo.