Drug delivery system making use of a hydrogel polymer coating

A vascular catheter for rapidly delivering drug into tissue or occlusive formation at a desired location of the wall of a vascular lumen, effective to reduce blood clotting problems or proliferation of smooth muscle cells that may impede blood flow, comprising:

• a catheter constructed for insertion into a vascular lumen having a catheter shaft and an expandable portion mounted on said catheter shaft, said expandable portion being expandable in response to controlled inflation pressure to fill the cross-section of the vascular lumen and engage the tissue or occlusive formation of said vascular lumen,
• at least a part of the exterior surface of the expandable portion being defined by a coating of a tenaciously adhered swellable hydrogel polymer, and incorporated within said hydrogel polymer, a preselected aqueous-mobile drug to be delivered to said tissue or occlusive formation, said drug selected from the groups of drugs that reduce vascular lumen occlusion problems caused by blood clots or tissue cell proliferation,
• said hydrogel polymer selected to cause the coating to reach a characteristic swollen state of a thickness a number of times thicker than the thickness of the coating in its dry state as a result of absorption of aqueous fluid, and, when in said swollen state, said coating having characteristic compressibility, in response t compressive pressure within said expandable portion elevated above said inflation pressure, to squeeze the coating against said tissue or occlusive formation sufficiently to immediately, substantially, reduce the coating thickness, and force a substantial portion of said aqueous-mobile drug into said tissue or occlusive formation, thereby to enable rapid administration of a desired dose of said drug into said tissue or occlusive formation.

A vascular balloon catheter for rapidly delivering a dose of a preselected aqueous-mobile drug into tissue or occlusive formation at a desired location of the wall of a vascular lumen, comprising:

• a catheter constructed for insertion into a vascular lumen having a catheter shaft and an expandable dilatation balloon mounted on said catheter shaft, said expandable balloon being expandable by an expansion controller to press against said tissue or occlusive formation at a compressive pressure in the range of about 1 to 20 atmospheres, said compressive pressure being elevated above the inflation pressure needed to fill the cross-section of the vascular lumen and engage the tissue or occlusive formation of said vascular lumen,
• at least a portion of the exterior surface of the expandable balloon being defined by a coating of a tenaciously adhered swellable hydrogel polymer having said dose of said aqueous-mobile drug incorporated therein, said hydrogel polymer selected to cause the coating to reach a characteristic swollen state of a thickness a number of times thicker than the thickness of the coating in its dry state as a result of absorption of aqueous fluid, and, when in said swollen state, said coating having characteristic compressibility, in response to said compressive pressure within said expandable balloon elevated above said inflation pressure, to squeeze the coating against said tissue or occlusive formation sufficiently to immediately, substantially, reduce the coating thickness, and force a substantial portion of said dose of said aqueous-mobile drug into said tissue or occlusive formation, said hydrogel polymer coating further characterized by having the capacity to incorporate a predetermined substantial amount of aqueous fluid and said drug and by being swellable by a factor of about 6 or more from a dried state to have a thickness in the range of about 10 to 50 microns in the swelled state,
• whereby rapid site specific release of a desired dose of about 20% or more of said aqueous-mobile drug from said hydrogel polymer coating is achieved during a brief interval of compression of said hydrogel polymer coating against the wall of the lumen when said expandable balloon is expanded in said pressure range.