Separation of cyclosporine metabolites: evaluation of high pressure liquid chromatographic column performance.

Cyclosporine has numerous metabolites that may contribute to its immunosuppressive or toxicological properties. An adequate chromatographic separation of these metabolites must be achieved in order to determine their concentrations in biological fluids or to collect sufficient pure compound to test for pharmacologic or toxicologic activity. We evaluated six high pressure liquid chromatography (HPLC) columns for their ability to separate bile-derived cyclosporine metabolites using the critical separation of metabolite 17 from metabolite 1, and metabolite 1 from metabolite 18 as criteria for performance. Two octadecylsilane columns, the LC-18 by Supelco and the Resolve C-18 by Waters, provided adequate metabolite separation in less than 50 min using an HPLC gradient system.