Radiolabeled liposomal formulation

Recently, this method was adapted to label two commercially available liposomal formulations doxorubicin encapsulated in polyethylene glycol (PEG)-coated liposomes (Caelyx /Doxil ) (14) and daunorubicin encapsulated in small distearoyl-phosphatidyl-choline/cholesterol liposomes (Daunoxome ) (15). Although no DTPA was encapsulated in these liposomes, the labeling efficiency was typically between 70% and 80% and the radiolabeled preparations were stable in vivo during the time course of the experiment (four hours). Most likely, the lipophilic In-oxine avidly associates with the lipid bilayer and encapsulation of DTPA might not be necessary when the experimental observation period does not exceed four to six hours. 

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