Medical Balloons - Applications - Drug Delivery

High-pressure balloons are very useful in several different applications used for drug delivery. These techniques localize the medication and are an effective alternative to administering it intravenously, which delivers the drug systemically to unwanted areas throughout the whole body. One method that can be used to deliver a toxic drug to a blockage or lesion is to use two discrete balloons mounted on a catheter shaft to seal off the afflicted area, while the medication is infused through a port in the catheter between the two balloons. Once the treatment is complete, the fluid is drained, the area is flushed, and the balloons are deflated and retracted. A dog bone-shaped balloon can also be used to deliver drugs in a similar manner. The ends of the balloon can be of equal or different sizes, depending on the shape of the cavity or vessel. When inflated, the ends seal off the area to be treated, and the medication is infused through a hole or series of holes in the narrower center section of the balloon. The holes can be made in the surface of the balloon with a laser, hot wire, or drilling device creating a sort of sponge. This can also be done to virtually any balloon.

Two discrete balloons or a "dog bone" shaped balloon can be used to seal off an area to be treated without subjecting too large an area to the medication. This also limits the amount of some times very toxic and/or expensive medication needed.

Alternatively, an ultra-thin-walled PET balloon can be converted to a microporous membrane with hole sizes ranging from submicron to a few microns in diameter.

Drugs can also be coated onto the surface of a balloon and delivered to a specific site in the body. Transfer of the drug from a balloon's surface to the cavity wall can be accomplished with pressure, heat, laser light, etc. Experimentally, laser & thermal energy has been used to enhance the binding of heparin to an injured arterial wall. In the experiment, lesions were treated immediately after PTCA, with a laser balloon that had been coated with heparin. The results suggest that heparin therapy is a safe treatment that yields favorable acute angiographic results.¹