Page 64 - Safety Risk Management for Medical Devices

Biocompatibility and Risk Management 43

Much information can be derived from published literature, existing in-house
data, or suppliers of materials. Where such information is unavailable, chemical or
physical characterization, or biological testing may be required to gather the required
data.
Data requirements are less stringent for lower risk applications, e.g., temporary
intact skin contact, than for higher risk applications, e.g., brain implants.
Once the risk has been estimated, it is evaluated against the risk acceptance
criteria, which are defined in the risk management plan. For reduction of risks,
certain measures can be taken to bring the risks down as far as possible. For example,
replacement of a material that has toxicological risks, with a material that doesn’t have
toxicological risks is a design that is inherently safe. Other potential Risk Control
measure:

• Reducing exposure time
• Reducing exposure surface area
• Use of coatings/materials that reduce adverse biological response
• Changes to manufacturing processes to reduce/eliminate toxic additives, or
manufacturing aids
• Better cleaning/rinsing processes to remove toxic residues

Keep in mind that some Risk Control measures may introduce new Hazards, or
increased risks elsewhere in the design. In such cases, some retesting may become
necessary.
Biological evaluation of medical device materials relies on risk assessment to
provide justification for not conducting certain testing. This is valuable from a project
cost and schedule perspective, and more importantly from the ethical perspective in
that some animal testing may be avoided.
An important factor to consider is that even if a given material is shown to be
sufficiently safe by itself, it cannot be deduced that the same material when used in
combination with other materials will still be safe. Therefore the total device in its
final form, produced using the final processes is typically subject to biological testing.
As described in Chapter 24, Production and Postproduction Monitoring, data
from production and postproduction must be monitored for any occurrences of
adverse effects, including due to biocompatibility. Such learnings must be used to
update the risk management file as necessary.