Separation and determination of liposomal and non-liposomal daunorubicin from the plasma of patients treated with Daunoxome

Several liposomal formulations of anthracyclines have been developed recent ly and are currently used in the clinical setting. We describe a technique of separation and quantification of the liposomal and non-liposomal forms o f daunorubicin in the plasma of patients treated with DaunoXome, a liposoma l formulation of daunorubicin. The method we propose is based upon the prop erty of liposomes to cross reversed-phase C-18 silicagel cartridges without being retained, while non-liposomal drug is retained on the stationary pha se and is eluted with methanol. Extraction of liposomal and non-liposomal d aunorubicin from plasma, therefore, is performed in two steps. This techniq ue is rapid, can be automated in order to handle large series of samples, a nd the plasma can be frozen after sampling by addition of glycerol. The rec overy of liposomal daunorubicin as well as the precision, linearity and acc uracy of the technique appear satisfactory for pharmacokinetic purposes. (C ) 2001 Elsevier Science B.V. All rights reserved.