Irritation Test: Skin and Tissue Compatibility of Medical Devices

Biocompatibility Test Methods for Medical Devices (ISO 10993 Series)

What is Irritation?

Irritation is localized inflammation or irritation caused by a medical device or chemicals released from the device when they come into contact with skin or other tissues. This can be manifested by the following symptoms:

Redness (erythema)
Swelling (edema)
Itching
Numbness or burning sensation

Irritation is usually caused by substances contained in the device or chemical compounds released from the device.

Irritation Testing is performed to determine the local irritation potential of medical devices, materials or extracts, most often in an animal model, using skin or mucous membranes. The skin, eye, mucous membrane exposure and duration of contact should resemble the intended clinical use of the medical device.

In the intracutaneous test, extracts of the test material and blank are injected intradermally. The injection sites are scored for erythema and edema (redness and swelling). This procedure is recommended for devices that will communicate externally or have internal contact with the body or body fluids. It reliably detects the potential for localized irritation from chemicals that may be derived from the biomaterial.

In the skin irritation test procedure, the test material is applied directly to the skin of a rabbit and after 24 hours of exposure, the material is removed and scored based on observation.

ISO 10993-23 Standard and Irritation Tests

The ISO 10993 series sets international standards for the biological evaluation of medical devices. ISO 10993-23 is a specific standard that assesses the irritation potential of devices on skin or tissues. According to this standard, irritation tests are performed to understand the potential for the device to cause irritation during clinical use.

Objectives of the test

To determine whether the medical device or its components cause skin or tissue irritation.
To detect adverse effects on human health in advance.
To prove that the device is suitable for biological safety.

Irritation Test Methods

Within the scope of ISO 10993-23, irritation tests can be performed both in vivo (on living organisms) and in vitro (in a laboratory environment). These tests are tailored to the intended clinical use of the device.

1. In Vivo Irritation Tests

In vivo testing is usually performed on animal models and evaluates the irritation that may result from direct contact of the device with tissues.

Models Used: Animals with sensitive skin such as rabbits are preferred.
Test Duration: Typically, signs of irritation are evaluated within 72 hours.
Evaluation Criteria:

Redness (erythema) and swelling (edema) are graded.
The results are analyzed by calculating the irritation index.

2. In Vitro Irritation Tests

These animal-free tests offer a modern approach to device biological evaluation.

3D Cell Culture Models: Laboratory models that mimic human skin cells are used.
Reactive Chemical Tests: The irritation potential of chemicals released from the device is analyzed with special chemical reagents.
Advantages: A more ethical approach and high accuracy in terms of reproducibility.

3. Extraction Tests

Objective: To determine the irritation potential of chemicals released from the device.
Method: The device is kept in a suitable solution for a certain period of time and analyzes are performed from this solution.

4. Mucosal Irritation Tests

Special tests apply to devices that come into contact with mucosal tissues rather than skin. For example:

Oral or vaginal mucosa tests.

Nanolab Laboratories Group continues to provide services within the scope of Irritation Testing . We also provide services in Acute Systemic Toxicity Testing.

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