Biocompatible plastics and their importance in the medical device industry
By Archita Datta Majumdar

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Plastics have paved their way into every aspect of human life due to their unique properties of malleability, easily changeable shapes and forms and low cost of production. Significant developments in plastics technology have coincided with the advent of innovative medical devices — pacemakers, stents and hip-replacement devices — which have enabled medical solutions for all kinds of ailments and impairments. Despite their ease of use, plastics can bring the risk of health and environmental hazards that can undermine all medical efforts unless treated minutely at first. Hence, the need for biocompatibility which can reduce these risks and enable us to fully derive the benefits.

What is the biggest advantage of biocompatible plastics in healthcare?
  • 1. Low cost
  • 2. Patient safety
  • 3. Ease of production

Like many words in the English language, plastic can be traced to its Greek origin. It is derived from the word "plastikos" which means one that can be shaped or molded easily. Plastic history can be traced back to as far as the Middle Ages when it was made from bio-derived materials like treated cattle horns, egg and blood proteins, all of which are organic polymers.

In the 19th century, vulcanization led to more thermoset materials and accelerated the development of plastics. But its unprecedented use and demand was seen in the middle of the 20th century with the revolutionary chemical modification of natural materials, which led to the development of polystyrene (PS) and polyvinyl chloride (PVC). To define plastics, one would use the phrase "organic polymers of high molecular mass," but more often than not, plastics today are a mix of natural elements combined with synthetic ones derived from petrochemicals.

Pure plastics have relatively low toxicity due to the chemical inertness and insolubility in water. But when combined with additives, their toxic levels increase. Some of these toxic compounds contain human carcinogens and interfere with hormone functions when they leach out of the product. Therefore, regulatory authorities have set very stringent standards for the plastic manufacturing and production industry, especially those meant for the medical devices. Finished products need to meet all environmental, regulatory and legislative regulations and need to be 100 percent biocompatible plastics.

What does biocompatibility mean?

Simply put, biocompatibility is the ability of a material to act and perform without impairing basic immunological functions of the body. The use of biocompatible plastics in the medical field is aimed to enhance healing functions without causing injurious, negative physiological, allergic or toxic reactions.

There are several tests conducted to test the biocompatibility of a material, the chief of these being the Biological Reactivity Testing (USP Class VI), and ISO 10993, Biological Evaluation of Medical Devices. Testing includes chemical, thermal and mechanical tests, implantations, intracutaneous and systemic injections. Most biocompatible plastics intended for medical devices include medical grades of PVC and polyethylene, polycarbonate, PEEK, Ultem PEI, polypropylene, polysulfone and polyurethane, which undergo these stringent tests before they can be approved for use.

Typical applications of biocompatible plastics include:
  • Polyvinylchloride or PVC — Blood tubing, blood bags
  • Polyethersulfone or PES — Single and multi-lumen tubing, catheters
  • Polytetrafluoroethylene or PTFE — Catheter linings, single and multi-lumen tubing, synthetic blood vessels, endoscopes, surgical sutures, reconstructive surgery, soft tissue regeneration patches
  • Polyethylene (PE-UHMW or PE-LD & HD) — Surgical cables, artificial tendons and orthopedic sutures, tubing
  • Polyurethane or PU — Breathable wound dressings
  • Polyetherimide, PEI — Reusable and sterilizable applications, surgical skin staplers
  • Polycarbonate or PC — Medical instruments and containers with glasslike transparency, check valves and tubing connectors
  • Polysulfone or PS — Surgical and medical devices, clamps, artificial heart components, heart valves
  • Polyetheretherketone or PEEK — Dentistry products, rigid tubing
  • Polypropylene or PP — Heart valve structures
The advent and use of biocompatible plastics for medical devices has two main benefits. The range of applications has paved the way for better and enhanced caregiving. They have also enabled these safe and effective medical solutions to be available at much lower costs. This means they can meet the demands of modern medical science and technology and benefit a larger percentage of the masses at the same time.

Archita Datta Majumdar has been writing for various industries for more than 14 years. She has contributed articles to The Economic Times, the leading financial daily of India, and she loves research, business analysis and knowledge management, which paves the way for a steep learning curve.