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Controlled degradation of magnesium stents

A degradation time, magnesium alloy technology, applied in the fields of medical science, surgery, coating, etc., can solve the problems of rapid degradation of bare magnesium and inability to be used for arterial remodeling

Inactive Publication Date: 2011-04-13
MEDTRONIC VASCULAR INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Magnesium-based stents have acceptable cross-sections (like expandable balloons), and radial strength, but bare magnesium degrades rapidly and cannot be used for arterial remodeling

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0056] Metal bracket cleaning steps

[0057] Place the magnesium holder in a glass beaker and cover with reagent grade or better hexane. Place the beaker equipped with the hexane immersion stand in an ultrasonic water bath for 15 minutes at a frequency of about 25-50KHz. The scaffolds were then removed from the hexane and the hexane was discarded. Submerge the stents in reagent grade or better 2-propanol, and then treat the container containing the stents and 2-propanol using an ultrasonic water bath as before. After cleaning, the stents with organic solvents were thoroughly rinsed with distilled water, then immersed in 1.0 N sodium hydroxide solution, using an ultrasonic water bath as before. Finally, the scaffolds were removed from the NaOH, rinsed thoroughly with distilled water, and then dried overnight in a vacuum oven at 40 °C. The weight of the dried stent was recorded after cooling to room temperature in a dry environment.

Embodiment 2

[0059] Coating clean, dry stents

[0060] In the following examples, ethanol was chosen as the solvent, and the polymer was soluble in tetrahydrofuran (THF). One of ordinary skill in the art of polymer chemistry will readily pair the appropriate solvent system and polymer with optimum results without undue experimentation.

[0061] 250 mg of polycaprolactone (PCL) was added to 2.8 mL of THF and mixed until the PCL dissolved to produce a polymer solution.

[0062] Clean, dry stents were coated using spray techniques or by immersion in polymer solutions. The stents must be coated such that the final coating weight is approximately 10 μg-1 mg. Finally, dry overnight in a vacuum oven at 50 °C. Weigh the dried coated stent and record the weight. The degradation time of the resulting polymer coating was about 3 months.

Embodiment 3

[0064] Coating clean, dry stents

[0065] 250 mg of poly-D-lactide (PDL) was added to 2.8 mL of THF and mixed until the PCL was dissolved to produce a polymer solution.

[0066] Clean, dry stents were coated using spray techniques or by immersion in polymer solutions. The stents must be coated such that the final coating weight is approximately 10 μg-1 mg. Finally, dry overnight in a vacuum oven at 50 °C. Weigh the dried coated stent and record the weight. The degradation time of the resulting polymer coating was about 6 months.

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Abstract

Implantable medical devices, more specifically stents, are described herein comprising magnesium based core structures whose elimination times are slowed by the appropriate polymer coating. Appropriate biodegradable polymers are selected which are suitable to provide a specific degradation time for the magnesium based core structure. Bioactive agents are incorporated into the polymer coating in order to aid in the therapeutic effect of the stent.

Description

[0001] scope of invention [0002] This article describes an implantable medical device comprising a magnesium-based core whose clearance time is controlled by a suitable polymer coating. Select the appropriate biodegradable polymer to provide a slower degradation time for the magnesium-based core structure. Background of the invention [0003] Typically, implantable medical devices are intended for long-term therapeutic use and are not removed once implanted. In some cases, short-term treatment with an implanted medical device is required. However, removal requires highly invasive surgical procedures, putting patients at risk of life-threatening complications. Medical devices that are degraded by normal metabolic pathways and absorbed by surrounding tissues need to be designed for short-term applications. [0004] Furthermore, recent advances in in situ drug delivery have led to the development of implantable medical devices that specifically deliver therapeutic compositio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A61L31/02A61L31/10A61L31/14A61L31/16
CPCA61L31/16A61L31/022A61L31/148A61L31/10A61L2300/432
Inventor C·(J)威尔考克斯
Owner MEDTRONIC VASCULAR INC