Purpose: To compare in vitro properties of 4 drug-eluting embolic agents loaded with doxorubicin. Materials and Methods: DC Bead (100-300 mm), LifePearl (200 mm), HepaSphere (30-60 mm), and Tandem (100 mm) microspheres were loaded with 40 mg/20 mL of doxorubicin per milliliter of microspheres. Loading, elution, diameter changes after loading, changes in the amount of doxorubicin loaded over 2 weeks in storage, and time in suspension were evaluated. Results: All microspheres loaded 4 99%

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... cin within 1 hour. In vitro elution reached a plateau by 6 hours, with 30% Ϯ 5, 21% Ϯ 2, 8% Ϯ 3, and 6% Ϯ 0 of the loaded doxorubicin eluted for LifePearl, DC Bead, HepaSphere, and Tandem microspheres, respectively, with at least 1 statistically significant difference between at least 2 of the products in doxorubicin eluted at every time point. The times to elute 75% of the total released doxorubicin were 197, 139, 110, and 77 min for DC Bead, LifePearl, HepaSphere, and Tandem microspheres, respectively. The average diameters of LifePearl, DC Bead, and Tandem microspheres were reduced after loading by 24%, 20%, and 9%, respectively. After suspension in contrast medium, no changes were observed in doxorubicin loading over 2 wk. After loading, times in suspension were 8.4 min Ϯ 0.2, 6.0 min Ϯ 0.1, 3.1 min Ϯ 0.2, and 2.9 min Ϯ 0.3 for Tandem, LifePearl, DC Bead, and HepaSphere microspheres, respectively. Conclusions: Although drug-eluting embolic agents universally loaded doxorubicin within 1 hour, the elution amounts, rates of release, diameter shrinkage, and times in suspension varied by product. ABBREVIATION HPLC = high performance liquid chromatography