Optimization of balloon coating process for paclitaxel coated balloons via micro-pipetting method

Surface Modification Using Ultraviolet-Ozone Treatment Enhances Acute Drug Transfer in Drug-Coated Balloon Therapy

Endovascular deployment of drug-coated balloons (DCB) is an emerging strategy for the revascularization of arterial disease. Randomized clinical trials have demonstrated DCB effectiveness, but a recent meta-analysis reported increased mortality risk in humans with use of DCBs containing the common antiproliferative drug paclitaxel. While many factors could have contributed to adverse outcomes, current DCB designs have poor drug delivery efficiency, risk of systemic toxicity, and limited potential to retain therapeutic drug concentrations within the arterial wall following the procedure. Our study focuses on developing a strategy to enhance acute drug transfer from the balloon to the arterial wall over the short procedural window (∼30-120 s). We employed ultraviolet-ozone plasma (UVO) treatment to increase the hydrophilicity of a prototypical balloon material (Nylon-12) and subsequently applied a urea-paclitaxel coating previously shown to undergo favorable adhesive interactions with the arterial wall under simulated ex-vivo deployment. A series of assays were performed to characterize our experimental DCBs in terms of UVO-induced alterations in balloon surface hydrophobicity, formed coating microstructure, coating stability, and acute drug transfer to the arterial wall. Obtained results suggest that the UVO-based surface modification of angioplasty balloons is a promising design strategy and highlights the critical role of coating microstructure in determining the drug transfer efficiency in DCB therapy.

Development of an automated micropipette coating method for drug-coated balloons

Drug-coated balloons (DCBs) are a recent technology developed to treat peripheral artery disease (PAD). Along with a suitable formulation of antiproliferative drug and excipient, coating method is an important aspect of a DCB as these factors affect coating characteristics and drug delivery to the treatment site. The multiple release tailored medical devices DCB (MR-TMD-DCB), designed to achieve multiple inflations to treat complex PAD, contains paclitaxel (PAT) as the antiproliferative drug and polyethylene oxide (PEO) as the excipient. In our previous studies, the MR-TMD-DCB was coated using a manual dip coating method. In this study, an automated micropipette coating method was developed using a modified spray coating instrument to coat the MR-TMD-DCB. First, the coating formulation and strategy was optimized. A drug formulation of 16 wt% PAT and 4% wt/vol PEO, a polymer formulation of 2.5% wt/vol PEO, and a total of two drug layers produced a mostly uniform and thin coating with no defects and acceptable drug load. The balloon also had optimal drug uptake in arterial tissue in an in vitro flow model. Next, the reproducibility of the coating strategy was improved by optimizing the instrument parameters. The optimized instrument parameters (translational speed = 0.150 in/s, revolution rate = 100 rpm, flow rate = 0.6 ml/min) resulted in improved reproducibility of the drug load and similar coating properties as the DCB. This study demonstrated the ability to automate the micropipette process to obtain a balloon with optimal coating properties and drug tissue uptake.