Microparticle coated medical device
A drug-loaded microparticle is applied to a medical device for subsequent application to biological tissues. A method of formulating a drug-loaded microparticle and applying it to the surface of a medical device, such as a stent, is disclosed. The drug-loaded microparticle is formulated by combining a drug with various chemical solutions. Specified sizes of the microparticles and amounts of drug(s) contained within the microparticles may be varied by altering the proportions of the chemicals/solutions. In addition to various drugs, therapeutic substances and radioactive isotopes may also be loaded into the microparticles. The drug-loaded microparticle are suspended in a polymer solution forming a polymer matrix. The polymer matrix may be applied to the entire surface or only selected portions of the medical device via dipping, spraying or combinations thereof.
1. A drug loaded stent, comprising:
a radially expandable stent body,
a coating layer disposed on the stent body, and
polymeric particles containing a therapeutic substance embedded within the coating layer, wherein the coating layer comprises a polymer different than the polymer from which the particles are made, wherein the coating layer is free from any therapeutic substances.
2. The stent of claim 1 , wherein the polymeric particles are made from a hydrogel material.
3. The stent of claim 1 , wherein the particles are 0.5 to 2 microns in size.
4. The stent of claim 1 , wherein the therapeutic substance is for the treatment of restenosis.
5. The stent of claim 1 , wherein the therapeutic substance is a radioactive isotope.
6. A medical device, comprising an implantable substrate and a coating layer, wherein the coating layer is free from any therapeutic substances but includes particles of a polymeric material having a therapeutic substance added thereto, wherein the therapeutic substance is completely encased within the polymer particles.
7. The stent of claim 1 , wherein the therapeutic substance is completely encased within the polymeric particles.
8. The medical device of claim 6 , wherein the coating layer comprises a polymer different than the polymer from which the particles are made.
9. An implantable medical device made by the method comprising:
adding polymeric particles containing a therapeutic substance to a fluid form of an implantable medical device coating material, wherein the coating material includes a polymeric material dissolved in a solvent, and wherein the polymeric particles containing the therapeutic substance are suspended in the polymeric material dissolved in the solvent;
applying the fluid form of the coating material comprising the polymeric particles added thereto to an implantable medical device; and
solidifying the coating material to a film layer by allowing the solvent to evaporate, wherein the film layer includes the polymeric particles containing the therapeutic substance.
10. The implantable medical device of claim 9 , wherein the film layer includes the polymeric material encasing the polymeric particles.