Biocompatibility standard ISO 10993

Introduction

For medical devices that directly or indirectly contact patients, biocompatibility testing is required to obtain regulatory approval in most markets. Biocompatibility tests help determine whether a device performs as intended without causing any adverse or harmful effects for patients or users, and mitigate any biological risks posed by the device.

ISO 10993 is the key standard used for medical device biocompatibility testing. The standard has 20 parts; the first part is ISO 10993-1 that provides information on how to evaluate the biological risk. The other sections define detailed test methods for different kinds of tests.

In order to include biological safety in the design of a new device, the ISO 10993-1 should be considered during the early stages of the design.

Designers shall define if the device is intended for short time, long time or permanent use and the amount of device invasiveness (intact skin, breached skin, blood, tissues and so on).

According to this device description, the ISO 10993-1 provides areas of interest and test methods to determine the biocompatibility risk potential. Of course, the testing for an implantable permanent medical device is more thorough than the testing for a device that comes in contact with intact skin for a very short time.

Since the testing for biocompatibility involves chemical, physical characterisation and also in vitro and in vivo testing for some device categories, designers are invited to review current information in the literature before planning for material testing.

Some definitions

Biocompatibility

Ability of a material to perform with an appropriate host response in a specific application

Biological risk

Potential for a substance to cause harm to health by virtue of its toxicity

Biological safety

Freedom from unacceptable biological risk

Biocompatibility Testing

ISO 10993-1 includes a table (see Table 1 below) that provides “… a framework for the development of an assessment program…” where, for the various intended uses, a general biological test strategy is described. Within the table, the toxicological effects to be considered based on the intended use of the device are marked with an “X”. The manufacturer should consider if data are available which cover the marked biological effects. If the biological effect is determined to be not relevant for this device, or if adequate data are available, further testing in this category is not needed. Thus, an “X” in the aforementioned table does not mean that a test is a required.

Classification by nature of contact

Surface devices

Skin
Mucosal membrane
Breached or compromised surface

External communicating devices

Blood path, indirect
Tissue, bone, dentin
Circulating blood

Implant devices

Tissue, bone
Blood

Classification by contact duration

Limited exposure (A):

Devices whose single or multiple use or contact is likely to be up to 24 h

Prolonged exposure (B):

Devices whose single, multiple or long-term use or contact is likely to exceed 24 h but not 30 days

Permanent contact (C):

Devices whose single, multiple or long-term use or contact exceeds 30 days

Note:

Repeated device application requires appropriate testing
In-situ polymerizing or biodegradable devices require testing of final polymer, starting materials, intermediate and degradation products

_{Table 1 - Biocompatibility testing accordi to ISO 10993}