Localized delivery of drug agents

1. A medical device, comprising:

a balloon that is expandable from an unexpanded state to an expanded state;

an elastic sheath over said balloon, said elastic sheath being expandable from an unexpanded state to an expanded state and having at least one slit therein, said slit having a first side and a second side, wherein said first side and said second side are substantially closed in the unexpanded state, and said first side and said second side pull away from each other in the expanded state; and

a drug agent carried by the medical device such that when said at least one slit is substantially closed, said drug agent is substantially retained by the elastic sheath,

wherein when said balloon is in the unexpanded state, said elastic sheath is in the unexpanded state, and when said balloon is expanded to the expanded state, said elastic sheath is expanded to the expanded state and said at least one slit is substantially open such that said drug agent is delivered from said medical device.

2. The medical device of claim 1 , wherein the medical device further comprises a polymer for carrying the drug agent, the polymer selected from the group consisting of polycarboxylic acids, cellulosic polymers, gelatin, polyvinylpyrrolidone, maleic anhydride polymers, polyamides, polyvinyl alcohols, polyethylene oxides, glycosaminoglycans, polysaccharides, polyesters, polyacrylamides, polyethers, polyurethane dispersions, acrylic latex dispersions, and mixtures and copolymers thereof.

3. The medical device of claim 1 , wherein said drug agent comprises a drug agent selected from the group consisting of pharmaceutically active compounds, proteins, oligonucleotides, DNA compacting agents, recombinant nucleic acids, gene/vector systems, and nucleic acids.

4. The medical device of claim 1 , wherein said elastic sheath comprises a material selected from the group consisting of ethylene vinyl acetate, latexes, urethanes, polysiloxanes, styrene-ethylene/butylene-styrene block copolymers, aliphatic polyesters, and mixtures and copolymers thereof.

5. The medical device of claim 1 , wherein said drug agent comprises paclitaxel.

6. The medical device of claim 1 , wherein said at least one slit comprises a plurality of slits arranged in a staggered pattern.

7. The medical device of claim 1 , wherein said balloon comprises at least part of a portion of a balloon catheter.

8. The medical device of claim 7 , wherein said elastic sheath is tubular and surrounds said balloon portion of said balloon catheter.

9. The medical device of claim 1 , wherein said balloon is not configured to receive a drug agent therethrough.

10. The medical device of claim 1 , further comprising a stent over the elastic sheath.

11. A method for the localized delivery of a drug agent to a target location within a mammalian body, comprising the steps of:

using a medical device comprising:

a balloon that is expandable from an unexpanded state to an expanded state;

an elastic sheath over said balloon, said elastic sheath being expandable from an unexpanded state to an expanded state and having at least one slit therein, said slit having a first side and a second side, wherein said first side and said second side are substantially closed in the unexpanded state, and said first side and said second side pull away from each other in the expanded state; and

a drug agent carried by the medical device such that when said at least one slit is substantially closed, said drug agent is substantially retained by the elastic sheath,

wherein when said balloon is in the unexpanded state, said elastic sheath is in the unexpanded state, and when said balloon is expanded to the expanded state, said elastic sheath is expanded to the expanded state and said at least one slit is substantially open such that said drug agent is delivered from said medical device;

delivering said medical device to said target location while said elastic sheath is in the unexpanded state and said at least one slit is substantially closed; and

expanding said balloon to thereby expand said elastic sheath to the expanded state such that said at least one slit is substantially open, whereby the drug agent is delivered from said medical device.

12. The method of claim 11 , wherein said drug agent is incorporated into said medical device by the steps of:

expanding said balloon to thereby expand said elastic sheath such that said at least one slit is substantially open;

exposing said drug agent to said medical device while said at least one slit is substantially open; and

deflating said balloon to thereby return said elastic sheath to the unexpanded state such that said at least one slit is substantially closed.

13. The method of claim 11 , wherein said drug agent is selected from the group consisting of pharmaceutically active compounds, proteins, oligonucleotides, genes, DNA compacting agents, gene/vector systems, and nucleic acids.

14. The method of claim 11 , wherein said elastic sheath comprises a material selected from the group consisting of ethylene vinyl acetate, latexes, urethanes, polysiloxanes, styrene-ethylene/butylene-styrene block copolymers, aliphatic polyesters, and mixtures and copolymers thereof.

15. The method of claim 11 , wherein said at least one slit comprises a plurality of slits arranged in a staggered pattern.

16. The method of claim 11 , wherein said balloon comprises at least part of a portion of a balloon catheter.

17. The method of claim 16 , wherein said elastic sheath is tubular and surrounds said balloon portion of said balloon catheter, said tubular elastic sheath having proximal and distal ends.

18. The method of claim 17 , wherein said proximal and distal ends of said elastic sheath are attached to said balloon catheter such that said balloon portion is completely covered by said elastic sheath.

19. The method of claim 11 , wherein said medical device comprises an iontophoresis catheter or an electroporation catheter.

20. The method of claim 11 , further comprising a stent over the elastic sheath.