Reduced temperature sterilization of stents

• US 7,998,404 B2
• Filed: 07/13/2006
• Issued: 08/16/2011
• Est. Priority Date: 07/13/2006
• Status: Expired due to Fees

• Current Assignee: Advanced Cardiovascular Systems Incorporated (Abbott Laboratories)
• Original Assignee: Advanced Cardiovascular Systems Incorporated (Abbott Laboratories)
• Inventors: Castro, Daniel, Gale, David C., Huang, Bin, Freeman, Abigail
• Primary Examiner(s): Conley; Sean
• Assistant Examiner(s): YOO, REGINA M
• Application Number:
  US11/486,690
• Publication Number:
  US 20080010947A1
• Time in Patent Office: 1,860 Days
• Field of Search: 422/22, 422/261, 422/291
• US Class Current: 422/22
• CPC Class Codes: A61L 2/08 Radiation
• CPC Class Codes: A61L 2/081 Gamma radiation
• CPC Class Codes: A61L 2/082 X-rays
• CPC Class Codes: A61L 2/085 Infrared radiation
• CPC Class Codes: A61L 2/087 Particle radiation, e.g. electron-beam, alpha or beta radiation
• CPC Class Codes: A61L 2/10 Ultraviolet radiation
• CPC Class Codes: A61L 2202/23 Containers, e.g. vials, bottles, syringes, mail
• CPC Class Codes: A61L 2202/24 Medical instruments, e.g. endoscopes, catheters, sharps
• CPC Class Codes: B65B 55/00 Preserving, protecting or purifying packages or package contents in association with packaging by packaging under special atmospheric or gaseous conditions B65B31/00; devices for placing protecting sheets, plugs, or wads over contents B65B61/22
• CPC Class Codes: B65B 55/16 by irradiation

Abstract

Methods and systems for reduced temperature radiation sterilization of stents are disclosed.

Claims

1. A method of sterilizing a stent comprising:

providing a stent-catheter assembly including a polymer stent crimped to a balloon of a balloon catheter, the stent having a stent strut and a crimped diameter;

selecting a sterilization temperature for the stent, wherein the sterilization temperature is selected by criteria including reducing the number of cracks in the stent strut after the stent is made sterile and expanded from the crimped diameter to a deployed diameter by the balloon, the sterilization temperature being below ambient temperature;

cooling the stent to the sterilization temperature; and

exposing the cooled stent to a plurality of doses of radiation sufficient to sterilize the cooled stent.

2. The method of claim 1, wherein the plurality of doses of radiation is sufficient to sterilize the stent.

3. The method of claim 1, wherein the sterilization temperature is less than 0.degree. C.

4. The method of claim 1, wherein the stent comprises a biostable polymer, biodegradable polymer, or a combination thereof.

5. The method of claim 1, wherein the stent comprises a coating including a biostable polymer, biodegradable polymer, drug, or a combination thereof.

6. The method of claim 1, wherein the radiation is selected from the group consisting of e-beam, gamma ray, ultraviolet, infra-red, ion beam, x-ray, and laser.

7. The method of claim 1, further including the step of cooling the polymer stent after the exposing the cooled stent to a plurality of doses of radiation step, wherein cooling the stent after the exposing the cooled stent to a dose of radiation slows down the rate of modification of the polymer material that is induced following the exposing step.

8. The method of claim 7, wherein the cooling steps occur only prior to the first of the plurality of exposing steps and after the last of the plurality of exposing steps.

9. The method of claim 8, wherein the sterilization temperature is selected to reduce the number of cracks having a length that is over 25% of the width of stent struts after the stent has been deployed by the balloon.

10. The method of claim 8, wherein the stent polymer is poly(L-lactide), the stent further including a poly(DL-lactide)-drug coating.

11. The method of claim 1, wherein the stent is a poly(L-lactide) stent.

12. A method of sterilizing a medical device, comprising:

providing a stent-catheter assembly including a poly(L-lactide) stent crimped to a balloon of a balloon catheter, the stent having a stent strut;

selecting a pre-sterilization temperature for reducing the number of cracks in the stent strut after the stent is made sterile and deployed from a crimped to a deployed diameter by the balloon, the pre-sterilization temperature being below ambient temperature;

cooling the stent-catheter assembly according to the pre-sterilization temperature;

exposing the stent-catheter assembly to a plurality of doses of radiation sufficient to sterilize the cooled stent-catheter assembly; and

cooling the stent-catheter assembly according to a post-sterilization temperature below ambient temperature after exposing the stent-catheter assembly to the dose of radiation, wherein the post-sterilization temperature slows down the rate of modification of poly(L-lactide) that is induced following the exposing step.

13. The method of claim 12, wherein the cooling the stent-catheter assembly to the pre-sterilization temperature occurs only prior to the first of the plurality of doses of radiation.

14. The method of claim 13, wherein the pre-sterilization temperature is selected to reduce the number of cracks having a length that is over 25% of the width of stent struts after the stent has been deployed by the balloon.

15. A method of sterilizing a stent, comprising:

providing a stent-catheter assembly including a polymer stent crimped to a balloon of a balloon catheter, the stent having struts and a crimped diameter;

sterilizing the stent-catheter assembly in a manner that will reduce the number of cracks in the stent struts after the stent is made sterile and expanded from the crimped diameter to a deployed diameter by the balloon, including the steps of

selecting a sterilization temperature for reducing the number of cracks formed when the stent is expanded by the balloon,

selecting a plurality of radiation doses to apply to the crimped stent and balloon for reducing the number of cracks formed when the stent is expanded by the balloon,

cooling the stent and balloon according to the selected sterilization temperature, and

applying the selected plurality of radiation doses to the cooled stent and balloon to sterilize the stent and balloon.

16. The method of claim 15, wherein a pre-sterilization temperature is selected to reduce the number of cracks having a length that is over 25% of the width of stent struts after the stent has been deployed by the balloon.

17. The method of claim 16, wherein the sterilizing the crimped stent and balloon in a manner that will reduce the number of cracks in the struts after the stent is made sterile and expanded from the crimped diameter to a deployed diameter by the balloon further includes the step of

cooling the stent-catheter assembly to a post-sterilization temperature below ambient temperature after exposing the stent-catheter assembly to the doses of radiation, wherein the post-sterilization temperature slows down the rate of radiation-induced modification of the polymer material forming the stent struts.

18. The method of claim 17, wherein the polymer stent is made from a polymer comprising poly(L-lactide).