Evaluation of pressure sensitive adhesives for drug eluting balloon

Abstract

Atheroscelerosis is a cardiovascular disease caused by accumulation of plaque in the walls of the blood vessel. There are many current medical devices which are used to treat atheroscelerosis. A catheter with deflated balloon is inserted into the diseased coronary artery. The balloon would be inflated and exert pressure to open the diseased coronary artery. A stent helps to keep the artery remain open. Although drug eluting stents and drug eluting balloons have been designed, drug eluting stent is not a good solution as restenosis will cause the diseased coronary artery to close after a few years. Drug eluting balloon was chosen as it has more advantages than drug eluting stents. The drug eluting balloon designed in this project has three layers, which are the wax releasing layer, PLGA film layer and bioadhesive layer. The bioadhesive layer is included in the design to transfer the PLGA film to the wall of the diseased coronary artery after balloon inflation using pressure. Nippi collagen casing was used as a cheaper alternative to swine aorta for preliminary mechanical testing, hence the mechanical properties of Nippi collagen casing and aorta were compared. Chitosan, Noveon-AA1, Carbopol 934P NF, 940 NF, 971P NF, 974P NF, 1342 NF were evaluated as bioadhesive layer in drug eluting balloon because these are the more commonly used bioadhesives in medical devices. In-vitro 180 degree peel test tensile adhesive test and swelling test were done on Nippi collagen casing to choose the 3 most suitable adhesive. Carbopol 940NF, Carbopol 974P NF and Noveon-AA1 were then tested on swine aorta substrate. 940NF had a higher swelling rate but lower maximum swell while Noveon AA1 had a lower swelling rate but higher maximum swell. 940NF Carbopol is recommended to be used for use in drug eluting balloon, however, due to higher swelling rate of 940NF Carbopol, Noveon AA-1 is recommended if the bioadhesive layer is used as a drug delivery vehicle.