Purpose: Drug coated balloons (DCB) are continually improving due to advances in coating techniques and more effective excipients. Paclitaxel, the current drug choice of DCB, is a microtubule-stabilizing chemotherapeutic agent that inhibits smooth muscle cell proliferation. Excipients work to promote coating stability and facilitate paclitaxel transfer and retention at the target lesion, although current excipients lack sustained, long-term paclitaxel retention. Keratose, a naturally derived protein, has exhibited unique properties allowing for tuned release of various therapeutic agents. However, little is known regarding its ability to support delivery of anti-proliferative agents such as paclitaxel. The goal of this project was to thus demonstrate the feasibility of keratose as a DCB-coating excipient to promote the release and delivery of paclitaxel.Methods: Keratose was combined with paclitaxel in vitro and the release kinetics of paclitaxel and keratose were evaluated through high performance liquid chromatograph-mass spectroscopy (HPLC-MS) and spectrophotometry, respectively. A custom coating method was developed to deposit keratose and paclitaxel on commercially available angioplasty balloons via an air spraying method. Coatings were then visualized under scanning electron microscopy and drug load quantified by HPLC-MS. Acute arterial transfer of paclitaxel at 1 h was assessed using a novel ex vivo model and further evaluated in vivo in a porcine ilio-femoral injury model.Results: Keratose demonstrated tunable release of paclitaxel as a function of keratose concentration in vitro. DCB coated via air spraying yielded consistent drug loading of 4.0 ± 0.70 μg/mm2. Under scanning electron microscopy, the keratose-paclitaxel DCB showed uniform coverage with a consistent, textured appearance. The acute drug transfer of the keratose-paclitaxel DCB was 43.60 ± 14.8 ng/mg at 1 h ex vivo. These measurements were further confirmed in vivo as the acute 1 h arterial paclitaxel levels were 56.60 ± 66.4 ng/mg.Conclusion: The keratose-paclitaxel coated DCB exhibited paclitaxel uptake and achieved acute therapeutic arterial tissue levels, confirming the feasibility of keratose as a novel excipient for DCB.

Aim Non-stent drug delivery platforms have recently emerged as an alternative treatment of peripheral arterial disease. Perfusion catheters have the potential to directly deliver anti-proliferative agents to the medial arterial layer to prevent restenosis. The purpose of this study was to therefore determine the effectiveness of a perfusion catheter to deliver paclitaxel, a proven anti-proliferative agent, to combat restenosis. Methods A bench-top model was utilized to determine the varying parameters of a novel occlusion perfusion catheter to maximize paclitaxel delivery using pharmacokinetic evaluation and fluorescent microscopy. Parameters tested included concentration of paclitaxel, delivery pressure, duration of delivery, and the use of an excipient. In addition, bilateral rabbit iliac arteries were treated with the perfusion catheter and pharmacokinetic evaluation performed at 1 hour, 1 day and 3 days. Results Bench-top testing demonstrated uniform and circumferential penetration of paclitaxel within the treated arteries. The results of the ex vivo test identified two groups with and without an excipient with similar loading conditions (with excipient: 15.4±8.6 ng/mg vs. without excipient: 8.9±6.9 ng/mg, p = 0.77). The in vivo pharmacokinetic analysis of these two groups demonstrated the use of contrast agent increased arterial paclitaxel levels and maintained initial paclitaxel dosing up to 3 days (With excipient: 1 hr: 107±62 ng vs. 3 days: 40±23 ng, p = 0.824; No excipient: 1 hr: 247±120 ng vs. 3 days: 2.92±2.9 ng, p=0.009). Conclusions These results demonstrate the feasibility to deliver paclitaxel directly to the medial layer of an artery via a perfusion catheter.

Drug coated balloons (DCB) are becoming the standard-care treatment for peripheral arterial disease (PAD). DCB use excipients to transfer and retain anti-proliferative drugs, such as paclitaxel. Excipients thus play a vital role in the design and function of DCB, however methods to coat balloons with excipients and anti-proliferative drugs remain unknown. The goal of this study was to thus develop an approach to coat and evaluate DCB for various excipients. An air sprayer method was developed to deposit paclitaxel and various excipients onto non-coated commercially available angioplasty balloons. The coating of the angioplasty balloons was evaluated for drug deposition and coating efficiency using high performance liquid chromatography tandem mass spectrometry. Drug transfer and retention of the coated angioplasty balloons into arterial segments were evaluated ex vivo using harvested pig arteries in a pulsatile flow bioreactor. The air sprayer method successfully delivered varying excipients including bovine serum albumin (BSA), urea and iohexol. The air spray method was configured to coat four angioplasty balloons simultaneously with paclitaxel and iohexol with an average paclitaxel load of 4.0 ± 0.70 µg/mm. The intra-day (within) and inter-day (between) coating precisions, defined as relative standard deviation (RSD), was 17.2 and 15.5%, respectively. Ex vivo deployment of iohexol-paclitaxel DCB yielded an arterial paclitaxel concentration of 123.4 ± 44.68 ng/mg (n = 3) at 1 h, 126.7 ± 25.27 ng/mg (n = 3) at 1 day, and 12.9 ± 12.88 ng/mg (n = 3) at 7 days. This work provides proof-of-concept of a quick, inexpensive approach to coat commercially available angioplasty balloons with paclitaxel and various excipients.

Current strategies to prevent restenosis following endovascular treatment include the local delivery of anti-proliferative agents to inhibit vascular smooth muscle cell (VSMC) proliferation and migration. These agents, not specific to VSMCs, are deposited on the luminal surface and therefore target endothelial cells and delay vascular healing. Cell-targeted therapies, (e.g., RNA aptamers), can potentially overcome these safety concerns by specifically binding to VSMC and inhibiting proliferation and migration. The purpose of this study was to therefore demonstrate the ability of a perfusion catheter to deliver cell-specific RNA aptamer inhibitors directly to the vessel wall. RNA aptamers specific to VSMCs were developed using an in vitro cell-based systematic evolution of ligand by exponential enrichment selection process. Two aptamers (Apt01 and Apt14) were evaluated ex vivo using harvested pig arteries in a pulsatile flow bioreactor. Local drug delivery of the aptamers into the medial wall was accomplished using a novel perfusion catheter. We demonstrated the feasibility to deliver aptamer-based drugs directly to the medial layer of an artery using a perfusion catheter. Such cell-specific targeted therapeutic drugs provide a potentially safer and more effective treatment option for patients with vascular disease.

Local drug delivery of paclitaxel is becoming ever more prevalent. As complex drug/excipient combinations are being developed and tested, new high performance liquid chromatography-mass spectrometry (HPLC-MS) techniques capable of quantifying paclitaxel from such formulations are needed. Here a method for quantifying paclitaxel from aqueous, protein and oil containing samples was developed and validated. Keratin, derived from human hair, is the protein component/paclitaxel excipient in the development and validation of said method. The novelty of this method is described by its ability to overcome water solubility issues and address clean-up of residual solvents in clinical grade paclitaxel injection composition. The method evaluates tert-butyl methyl ether and ethanol as extraction solvents with an extraction efficiency of 31.9 ± 2.3% and 86.4 ± 4.5% respectively. Upon evaporation and rehydration, samples were evaluated by HPLC-MS and a method was developed for paclitaxel quantification. The method developed had an inter-day precision of 9.1% relative standard deviation and an intra-day precision of 4.3% relative standard deviation normalized to a docetaxel internal standard. The described method is applicable to any aqueous paclitaxel sample containing protein and/or oils.