Importance Of Biocompatibility For
Medical Polymers
And Regulatory Requirements
K. R. Navaneethakrishnan, MSc,
ERT
Assistant Director,
GLR Laboratories Private Limited, Chennai |
Medical polymers are a blessing in disguise. Polymers
have played a big part in the creation of medical
devices in recent years due to their low density,
which means they are light in weight, which is another
advantage for patients if they are implanted.
Injection moulding on a big scale allows for the
creation of complicated shapes at a lower cost, as
well as the ability to develop a material to match a
specific application.
In the case of medical devices, the commonly used
polymer groups are:: non-degradable synthetic polymers
(e.g. polyethylene, polymethylmethacrylate, silicone);
naturally occurring polymers (e.g. cellulose,
alginate, gelatin, collagen); and biodegradable
polymers (e.g. poly (L-lactic
acid) (PLLA), polyglycolic acid). Examples of devices
made of polymers are listed below: |
• Polypropylene or PP —
disposable syringes, membranes for membrane oxygenators,
connectors
• Polyvinylchloride or PVC - intravenous (IV) tubing,
blood bags
• Polyethersulfone or PES — anesthesia masks, single and
multi-lumen tubing
• Polytetrafluoroethylene or PTFE — surgical sutures,
catheters
• Polyurethane or PU — catheters, medical gloves, and
wound dressings
• Polyetherimide, PEI — surgical skin staplers
• Polycarbonate or PC — artery cannulas, stopcocks, luers,
blood filter housings, dialyzer housings, insulin pens,
surgical device
• Polysulfone or PS — Membranes and fluid handling
applications
• Polyetheretherketone or PEEK — dentistry products, rigid
tubing, catheters, disposable surgical instrument
• Polypropylene or PP — syringes, and closures, sutures,
drapes, and gowns, medical trays
• Polyethylene (PE-UHMW or PE-LD & HD) — orthopedic
sutures, tubing, packaging films, pouches, knee
arthroplasty and total joint replacement.
Because most naturally produced polymers are found in the
structural tissues of living animals, they have various
advantages over synthetic polymers, including
biocompatibility, biodegradability, and biological
activity. Synthetic polymers can be customised to fulfil a
certain absorption time requirement, thus improving
repeatability and scale-up while avoiding the risk of
disease transmission that naturally occurring polymers
often provide.
Polymers
have found their way as a convincing solution for many
medical conditions in the form of various innovative
medical devices. Nevertheless, it cannot be taken for
granted that the use of medical polymers is risk-free. The
impact of the quality of the raw material used, the
manufacturing process, process additives, packaging
materials used and the sterilization method used, each one
of these parameters can contribute to the risk. In order
to explore and fully utilize the tremendous benefits that
medical polymers can offer, we need to study their
biocompatibility.
Lack of biocompatibility of a
device can result in a variety of biological and
non-biological problems. When these dangers come into
contact with the human body, they have the potential to
cause injury. Chemicals present in the medical device that
can enter the human body, implants that might trigger an
immune response, deformed or damaged materials or portions
of a medical device, and so on are some examples of
potential causal risk agents. Polymeric materials often
contain a small amount of Low Molecular Weight Chemicals (LMWC)
such as additives, catalyst, processing aids, and
radiation products. These LMWC may be potentially
genotoxic.
Biocompatibility can be defined as the relationship
between a material and the organism so that neither
produces undesirable effects. Biological evaluation of
medical devices is a mandatory regulatory documentation
for medical device registrations. This documentation
comprises of the biological evaluation plan (BEP) and the
biological evaluation report (BER), as part of a risk
management process in accordance with ISO 14971:2019
(Medical devices — Application of risk management to
medical devices), Annex I. This
risk management process involves identification of
biological hazards, estimation of the associated
biological risks, and determination of their
acceptability. According to ISO 10993- 1:2018 (Biological
evaluation of medical devices — Part 1: Evaluation and
testing within a risk management process), the
biological evaluation shall be planned, carried
out, and documented by knowledgeable and experienced
professionals. |