Background: According to current understanding the drug-coated balloon (DCB) carries a sufficient dose of an effective antineoplastic agent, i.e. paclitaxel, to the target lesion.
Methods: Literature review and report on experimental studies simulating the access of coated balloons to the treatment site and studies in pigs.
Results: The drug adheres to the balloon membrane and is partially hidden below the folds which are wrapped around the shaft. Upon inflation solid paclitaxel particles are pushed into the vessel wall. Premature loss of paclitaxel and transfer to the vessel wall are controlled by the coating formulation which includes an inactive additive. Particles in the tissue dissolve slowly resulting in a terminal half-life of almost 2 months. The very low solubility of paclitaxel minimizes premature loss of the drug, dissolution, and elimination, while maximizing efficacy and tolerance are limited by the very low solubility of paclitaxel. From an exemplary DCB, approximately 10% of drug is lost before the target lesion is reached, 5-20% is transferred into the vessel wall and 10% remain on the balloon after withdrawal. The remainder of the drug is distributed in the general circulation. Inhibition of neointimal proliferation in animal models is reliable and as persistent as with drug-eluting stents. Histology reveals slight to moderate dose-dependent downstream effects without functional or clinical impairment.
Conclusion: Paclitaxel continues to be the drug of choice, the dose varies between 2 and 3.5 µg/mm² balloon surface. Neither animal experiments nor clinical trials have demonstrated problems in vessel segments treated with overlapping balloons. Future developments are expected to improve efficacy in additional disease conditions (e.g., calcified vessels) and vessel territories.