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Silicone Biomaterial Applications: Past, Present and Future

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Silicone Biomaterial Recap …

Silicone Biomaterial Recap
ƒ Enabled by the intrinsic properties of silicone materials…
ƒ … manifest in the aggregated properties of biocompatibility and biodurability,silicone in its 66 th year as a biomaterial
ƒSilicone biomaterials can help enable further improvements in medical technology and care

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  • 1. Silicone Biomaterial Applications: Past, Present and Future jim.curtis@dowcorning.com Select Examples
  • 2. 2 Silicone Kipping gave us the name “Silicone” based on the similarity of the organosilcon compounds he developed with ketones. Generally, we think of silicones as polymers with a backbone of silicon to oxygen bonds, but other structures such as silicate resins might also be called silicone. Si R R O Si CH3 CH3 O n siloxane polydimethylsiloxane and if R is CH3, Kipping, FS (1904). Organic derivative of silicon. Preparation of alkylsilicon chlorides. Proc. Chem. Soc. 20, 15. silicate resin
  • 3. 3 Silicone Properties of Interest in Medicine Thermal stability Chemical stability Electrical insulation High gas permeability Intriguing surface properties Low surface tension (20.4 mN/m)* Critical surface tension of wetting (24 mN/m) Water repellency *At the highest molecular weight pdms measured in Roe RJJ (1968) Phys. Chem., 70, 2013. Owen MJ (1981) Why silicones behave funny. Chemtech, 11, 288. Colas, André; Curtis, Jim (2004). Biomaterials Science, Second Edition: An Introduction to Materials in Medicine. Elsevier, Academic Press.
  • 4. 4 Host / Material Interactions Biodurability: Host has minimal adverse effect on material No material is suitable for every application… …but silicones have a strong history of stability in the body • PMDS is even added to increase the biodurability of other polymers such as polyurethane Biocompatibility: “The ability of a material to perform with an appropriate host response in a specific situation” No material is suitable for every application… …but silicones are often thought of as intrinsically biocompatible… … based on a long history of successful use in numerous applications Black, J. (1992). Biological Performance of Materials: Fundamentals of Biocompatibility. Marcel Dekker, New York. Remes, A., and Williams, D. F. (1992). Immune response in biocompatibility. Biomaterials, 13(11): 731. Colas, André; Curtis, Jim (2004). Biomaterials Science, Second Edition: An Introduction to Materials in Medicine. Elsevier, Academic Press Host Material
  • 5. Silicone Biomaterial Applications: Past, Present and Future Select Examples
  • 6. 6 Blood Coagulation Prevention Silicone’s water repellency caused it to be considered for prevention of blood coagulation in the 1940s. Toronto and Manitoba researchers coated syringes, needles, and vials with methylchlorosilane. When rinsed with distilled water, the silane hydrolyzed, forming a silicone coating on the glass and metal substrates which delayed blood clotting. Mayo Clinic researchers found storage in silicone-coated syringes did not affect blood coagulation time after being dispensed; declared silicone was “the most practical of any known [substance] for coating needle, syringe and tube.” Silicone precoating of needles, syringes, and blood collection vials became commonplace and continues today. Jaques, LB; Fidlar, E; Feldsted, ET; MacDonald, AG (1946). Silicones and blood coagulation. Can. Med. Assoc. J., 55, 26. Margulies, H; Barker, NW (1949). The coagulation time of blood in silicone tubes. Am. J. Med. Sci., 218, 42.
  • 7. 7 Needle Lubrication Silicone-coated needles penetrate easier. Today most hypodermic needles, syringes, and other blood- collecting apparatus are coated or lubricated with silicone. Silicone coated and non-coated hypodermic needle penetration force s measured by Melab equipment using DIN 13097. Photo courtesy of Melab GmbH..
  • 8. 8 Extracorporeal Equipment Silicone found application in extracorporeal machines, due to their permeability and hemocompatibility properties. Cardiac bypass, circa 1964 Silicone’s use in extracorporeal applications continues today. Hemocompatibility testing has suggested that phthalate-free silicone tubing may be superior to PVC. Harmand, MF; Briquet, F (1999). In vitro comparative evaluation under static conditions of the hemocompatibility of four types of tubing for cardiopulmonary bypass. Biomaterials 20(17), 1561. AV06443
  • 9. 9 Catheters, Drains and Shunts Silicone elastomers are used in catheters, shunts, and drains. silicone extrusions silicone-coating of other materials Silicone catheters, Drains and Shunts remain in use today.
  • 10. 10 catheter body seal PSA trocar Suprapubic Drainage Silicone suprapubic catheter sets remain in use today.
  • 11. 11 Early Long-Term Implants The first published report of silicone elastomers being implanted in humans was in April 1946, when Dr. Frank H. Lahey told of his use of these materials for bile duct repair. Dr. DeNicola implanted a silicone artificial urethra in 1948. Fourteen months after implantation, the artificial urethra “had been retained with normal genitourinary function.” Lahey, F. H. (1946). Comments made following the speech “Results from using Vitallium tubes in biliary surgery,” read by Pearse HE before the American Surgical Association, Hot Springs, VA. Ann. Surg., 124, 1027. DeNicola, R. R. (1950). Permanent artificial (silicone) urethra. J. Urol., 63(1), 168–172.
  • 12. 12 Hydrocephalus Shunt 1956 John Holter & son “Casey” Dr. Eugene Spitz identified need: Competent one-way valve that …could be sterilized & … remained stable in vivo Holter developed it in his garage using silicone rubber and tubing provided free from Dow Corning Baru, J. S., Bloom, D. A., Muraszko, K., and Koop, C. E. (2001). John Holter’s shunt. J. Am. Coll. Surgeons, 192, 79.
  • 13. 13 Hydrocephalus Shunt Holter & Spitz patented the design; it was commercialized by the Holter Company 1957 Reader’s Digest article regarding the Holter shunt spurred interest in silicone for medical applications Holter-designed valves remain available through Codman and Sophysa Baru JS, Bloom DA, Muraszko K, Koop CE (2001). John Holter’s shunt. J Am Coll Surgeons, 192, 79. LaFay, H. (1957). A father’s last-chance invention saves his son. Reader’s Digest, January, p 29–32. Modern hydrocephalus shunts and valves continue to use silicone. Modern Codman Hakim programmable valve shunt. Courtesy of Codman, a Johnson & Johnson company
  • 14. 14 Center for Aid to Medical Research 1959 Dow Corning Center for Aid to Medical Research Free clearing house for information & material samples Corresponded with > 35,000 medical professionals Braley, S. A. (1973). Spare Parts for Your Body. Dow Corning Center for Aid to Medical Research, Midland, MI.
  • 15. Artificial Organs 15 Dr. Michael E. DeBakey
  • 16. 16 Dedicated Production Site 1963 Dow Corning built a production plant dedicated to medical products featuring: rural location, positive pressure, ultraclean practices, biological surveillance, and lot traceability
  • 17. 17 Cardiac Valves Blood compatibility was a factor in the application of silicone in several mechanical heart valves Silicone heart values remain in use today Bhat SV. (2002) Biomaterials. Springer pp. 69.
  • 18. 18 Implantable Pacemakers Silicone was used in early pacemaker implants encapsulated the electronic components and “can” insulated the leads enabled waterproof connection Colas, André; Curtis, Jim (2004). Biomaterials Science, Second Edition: An Introduction to Materials in Medicine. Elsevier, Academic Press, Silicone remains in use in today’s modern pacemakers and leads.
  • 19. 19 Orthopedic Implants Silicone small joint implants Swanson, A. B. (1968). Silicone rubber implants for replacement of arthritic or destroyed joints in the hand. Surg. Clin. North Am., 48, 1113. Silicone small joint implants remain available today.
  • 20. 20 Orthopedic Implants Cement restrictors Silicone bone plugs remain available today.
  • 21. 21 Aesthetic Implants Silicone use in aesthetic and reconstructive implants Over 40 years Breast, Scrotum, Chin, Nose, Cheek, Calf, Buttocks Cronin design mammary prosthesis, 1964 Silicone testicular implants Silicone breast implants are available today; silicone gel testicular implants are not generally available in the USA Cronin TD, Gerow FJ. (1963). Augmentation mammaplasty: a new “natural feel” prosthesis. Transactions of the Third International Congress of Plastic Surgery—Excerpta Medica, Int. Congr. Ser., 66, 41.
  • 22. 22 Other Silicone Implants/Devices Silicone has been used in several other implants or devices Head Burr-hole covers Surgical products for treatment of retinal detachment Intraocular lenses (foldable) TMJ implants Cochlear implants Dental impression materials Breathing masks Nasogastric feeding tubes Braley, S. A. (1973). Spare Parts for Your Body. Dow Corning Center for Aid to Medical Research, Midland, MI. Colas, André; Curtis, Jim (2004). Biomaterials Science, Second Edition: An Introduction to Materials in Medicine. Elsevier, Academic Press These silicone devices remain available today with the exception of silicone TMJ implants, which are not.
  • 23. 23 Other Silicone Implants/Devices Silicone has been used in several other implants or devices Neck Tracheostomy tubes Artificial Larynx Urogenital Slings (urinary incontinence) Pessaries (incontinence, reconstruction) Penile Implants (impotence) Vaginal rings (drug delivery) These remain available today. Braley, S. A. (1973). Spare Parts for Your Body. Dow Corning Center for Aid to Medical Research, Midland, MI. Colas, André; Curtis, Jim (2004). Biomaterials Science, Second Edition: An Introduction to Materials in Medicine. Elsevier, Academic Press
  • 24. Silicone Biomaterial Applications: Past, Present and Future Select Examples
  • 25. 25 Wound Care Courtesy of Beiersdorf AG
  • 26. 26 Contact Lenses Silicone-Hydrogel Lens Dk increases with silicone content Approved for 30 days of continuous wear Fewer complications, more comfort Dillehay, S. M. (2007). Does the level of available oxygen impact comfort in contact lens wear?: A review of the literature. Eye Contact Lens, 33(3), 148-55.
  • 27. 27 Gastric Bands Silicone elastomer is used in the bariatric implants: Lap-Band® (Allergan) Realize® (Ethicon Endo-Surgery, J&J) BMI > 40 or Weight >45 kg above ideal In 2011, FDA allowed expanded indication BMI > 30… …plus diabetes or hypertension US FDA P000008 Lap-Band, P070009 Realize. Gastroenterology and Urology Devices Panel, December 3, 2010
  • 28. 28 Drug Delivery Applications Silicone PSA in TDDS patches Controlled release Compliance Rivastigmine for Alzheimer’s (Exelon®) Methylphenidate for ADHD (Daytrana®) Nicotine
  • 29. 29 Single-use Fluid Transport Systems in Pharmaceutical Manufacture FDA emphasis on process validation Ease of use, connect/disconnection Well-characterized low extractables profile
  • 30. Silicone Biomaterial Applications: Past, Present and Future Select Examples
  • 31. 31 Megatrends in Medicine Geo-expansion to emerging economies Personalized medicine Aging populations Rising healthcare costs Global pandemics Environmental concerns Evidence-based medicine Shortage of medical doctors Payer’s influence on care Prevention Harvard Business Review Special Report 2010.
  • 32. 32 Diagnostic Devices Lab-on-a-chip & biosensors using Microfluidics 3-D photolithography Printable electronics “Wearable” electronics Megatrends affected: Personalized Medicine Rising costs Aging Populations Global Pandemics Environmental concerns Second annual Lab-On-A-Chip World Congress, 2010, San Diego.
  • 33. 33 Tissue Engineering Elastomeric scaffolds Biocompatible constructs Progenitor cell “training” Prevention Healthcare-associated Infection Anti-infective materials in catheters and other devices Physical protection for the frail & elderly Combination products with active-loading to provide benefit Bettinger, CJ. Synthesis and microfabrication of elastomeric biomaterials for advanced tissue engineering scaffolds . Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.
  • 34. 34 Silicone Biomaterial Recap Enabled by the intrinsic properties of silicone materials… … manifest in the aggregated properties of biocompatibility and biodurability, silicone in its 66th year as a biomaterial Silicone biomaterials can help enable further improvements in medical technology and care
  • 35. 35 Our Continuing Commitment to Healthcare Dow Corning has been supplying silicone materials for short- and long-term implants for many decades We continue to supply these and develop new innovative products We operate under indemnification contracts for applications of over 29 days implantation to supply large OEMs and their fabricators We do not supply applications where our silicone is the active ingredient for contraception. We will supply for contraception where the silicone is an excipient, but under indemnification agreements. We do not sell silicone fluid for cosmetic injection or any other regulatory-excluded application
  • 36. 36 Dow Corning is ….. 36 A global leader in silicones and high purity silicon More than 7,000 products/services Approx 25,000 customers Approx 12,000 employees Strong and healthy financially: $6.43 billion sales in 2011 Investing in our future and our customers’ futures: geographic, manufacturing, innovation Transforming our business to deliver: Efficiency, Innovation and Sustainability Focused on sustainability and Responsible Care® 36 Dow Corning is a registered trademark of Dow Corning Corporation We help you invent the future is a trademark of Dow Corning Corporation Daytrana is a registered trademark of Noven Therapeutics, LLC Exelon is a registered trademark of Novartis AG Lap-Band is a registered trademark of Allergan, Inc. Realize is a registered trademark of Johnson & Johnson Corporation Thank you for your attention

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