Local intra-arterial drug delivery for prevention of restenosis - Comparison of the efficiency of delivery of different radiopharmaceuticals through a porous catheter

RATIONALE AND OBJECTIVES. Several radiopharmaceuticals were administered th rough a porous balloon catheter to compare the absolute amount deposited an d the retention in the vessel wall. The reported efficiency of local drug d elivery ranges from 0.001% to 0.1%, with poor retention after 24 hours. METHODS. An endothelin derivative (n = 61, pertechnetate (n = 6), hexamethy lpropylene amineoxime (HMPAO) (n = 5), ethyl cysteinate dimer (ECD) (n = 5) , and tin colloid In = 5) were labeled with 185 MBq/mL 99m-technetium. Afte r balloon denudation of the infrarenal aorta in 27 New Zealand White rabbit s, 100 muL of each agent was administered through a porous balloon at a pre ssure of 4 bar. Dynamic and static whole-body scintigrams were obtained for 24 hours. The infrarenal aorta was excised and the activity calculated in a gamma counter. RESULTS. Apart from their retention in the region of local administration, the radiopharmaceuticals showed different distribution patterns. The highes t regional tracer retention was observed with HMPAO, After administration o f HMPAO, a significant difference between regional (vessel wall plus surrou nding tissue: 14.5% of injected dose [ID]/24 hours) and Local (vessel wall: 1.8% ID/24 hours) delivery was found. In contrast, ECD was eliminated quic kly (local retention after 24 hours = 0% ID). The retention efficiencies we re HMPAO > endothelin derivative > tin colloid > pertechnetate > ECD, CONCLUSIONS. The different physicochemical and pharmacokinetic properties o f radiopharmaceuticals resulted in different delivery efficiencies after lo cal application.