Our 16th Year of Publication
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Cover Story

A General Overview of Silicones use in Medical Devices

Bill Riegler,
NuSil Technology LLC, U.S.A.

The Presentation covered My about overview of silicones and its used in medical devices. If includes history of silicones used in medical and drug delivery devices and the different material choices available to the current device designer.

The presentation included the following:

• Brief Company Overview
• History of Silicones in Medical devices
• History of Silicones in Drug Delivery
• Regulatory & Testing
• Material recommendations
• Summary


He introduced the company Nusil Technology LLC and briefly outlined the achievements of the companies as follows:

  • NuSil Technology LLC, founded in 1979

  • NuSil is the largest supplier of silicone for long-term implantable medical devices.

  • Headquartered in Southern California, U.S.

– Manufacturing sites in Carpinteria CA, Bakersfield CA, and Irving TX
– 31,587m2 Total manufacturing space
– Service Centers in US, France and Malaysia

  • 400+ employees

  • ISO-9001 certified since 1994

  • FDA Registered facility

– Manufacture the drug Simethicone

  • Quality System compliant with:

– 21 CFR Part 210/211 cGMP for Finished Pharmaceuticals
– ICH Q7 GMP for Active Pharmaceutical Ingredients
– IPEC GMP for Pharmaceutical Excipients

History of silicones goes back quite a few years back to the 1950s’. It is characterize as biologically inert. It is used in range of medical devices, probably the most researched biomaterials. The applications include pacemaker lead sheaths, hydrocephalus shunts, stent coatings, intraocular lenses. He mentioned an important point that as a raw material supplier their silicones are not approved by FDA. The FDA approves just the device manufacturers. He started with the history of silicones used in drug delivery and mentioned that the controlled release of drugs with silicones first started in the 1960’s. He introduced some well know drug medical devices know to be used in silicones as given in table 1 :

Table 1: Commercial devices incorporating silicone:

Trade Name Company Drug Type
Leiras Oy
Schering Oy
Contraceptive implant (CI)
Estring® Pharmacia/Upjohn 17-ß estradiol Intravaginal ring (IVR)
Nitriderm Novartis nitroglycerine Transdermal
Durogesic® Janssen-Cilag Fentanyl Transdermal
Nuvaring® Organon etonogestrel / ethinyl estradiol IVR
Mirena® Bayer Schering Oy levonorgestral IntraUterine System (IUS)

Giving brief history of Nusil’s involvement in healthcare industry, he highlighted the following :

  • 1982 development of silicone IOL material

  • 1985 supply materials for cosmetic surgery device market.

  • 1992 Dow Corning involved in litigation over mammary implants. Discontinuation of 5 “implant grade” products

  • FDA publishes Guidance that lays out procedure for ‘expedited review’

  • 1993 NuSil submits first Masterfile to U.S. FDA

  • Approximately 300 Masterfiles have been submitted since Regulatory & Testing

Talking about regulator and testing issued related to the silicones, he discussed about :

  • Masterfile
  • Class VI/ ISO10993
  • Short-term
  • Long-term
  • Drug Delivery

The first master file with FDA was submitted in early 1990s’. Since than that time about 300 master files have been submitted.

Master files have two major sections, the first portion is manufacturing portion in which we describe exactly how we manufacture the material. This is sent to the FDA. This information is not sent to anybody since it is proprietary. The next is the testing compendium. It involves several different type of testing like:

  • Bulk Physical Properties

  • Mechanical Properties

  • Chemical Properties

  • Confirmatory Biological testing

This type of tests can be obtained actually from device manufacturers as well as you can have access to our master file no maintained with the USFDA.

USP Class VI/ISO 10993

Introducing the USP (the United States Pharmacopoeia), he highlighted the following:

  • The United States Pharmacopoeia (USP) - independent organization that established standards that ensure the quality of medicines and other health care technologies

  • Class VI requirements are the most stringent class of USP test

  • ISO (The International Standards Organization) is composed of representatives from various national standard organizations which establish world-wide standards.

  • ISO 10993 – standard developed for the biological evaluation of medical devices currently a 20-part standard which is used to evaluate the effects of medical device materials on the body.

  • Most NuSil Healthcare materials meet or exceed all USP Class VI and many ISO-10993 test requirements

  • We can work with local governments/regulations Short-Term Medical Device What does that mean? We call these types of products as restricted products.

  • Short-term or external applications/medical devices

  • Implanted 29 days or less

  • NuSil designates these materials as Restricted

  • Examples of applications

  • Syringe o-rings and lubricants

  • Medical tubing

  • Gaskets

Long-Term Medical Device

  • These products have different testing and regulatory requirements.
  • Long-term, which may be considered for any application
  • Implantation greater than 29 days
  • Applications carry greater liability
  • NuSil designates these materials as Unrestricted
  • Applications include:

– Intraocular lenses
– Pacemaker leads
– Cosmetic implants

Drug Delivery Device

These types of devices are fairly new developed in last decades.

  • NuSil Product Designation

– Drug Delivery Unrestricted (DDU)

  • Regulatory Support

– Drug Master Files (DMFs) submitted to U.S. FDA
– Testing guided by European Pharmacopeia Monograph 3.1.9, Silicone
Elastomer for Closures and Tubing
– Lot-to-lot Testing
– ISO14949 – including hexane reflux extraction
– FT-IR to each uncured part of any DDU product
– Individual lot numbers assigned to each uncured part of any given DDU product

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