Buehler Assay (BA)

A big variety of chemical components such as starting materials and processing aids including lubricants and mould-release agents used in the manufacture of medical device, adhesive/solvent residues from assembly process, and sterilant residues from sterilization process may be present in a finished product. It shall be taken into consideration that whether these components have the potential sensitization activity.

The buehler assay is designed to evaluate the contact dermal sensitization caused by repeated skin exposure to the extract from medical device.

STEMart offers in vivo buehler assay for skin sensitizing potential investigation according to the biocompatibility guidelines modified for medical devices.

Standard of BA

• ISO 10993-10: 2010

BA Test Principle

Expose the test animals to the test substance by topical application. Following an induction period, which allows for the development of an immune response, expose the animals to a challenge dose. Compare the extent and degree of skin reaction to the challenge exposure in the test animals with that demonstrated by control animals which are sham treated during induction and receive the challenge exposure.

BA Test Animal

Guinea pig

BA Test Procedure

• Induction phase

With the filter paper patch or absorbent gauze soaked in the test substance, administer the test substance by topical application to the clipped left upper back region of test animals. Treat the control animals with blank liquid alone. Remove the patches and dressings after 6 ± 0.5 hours.

• Challenge phase

Challenge all test and control animals with filter paper patches or chambers soaked in the test substance at 14 ± 1 days after completion of the induction phase. Remove the patches and dressings after 6 ± 0.5 hours.

• Observation of animals

Visualize the formation of erythema on the skin under natural or full-spectrum lighting.

• Result interpretation

Positive results:

• Grades of less than 1 in control group: grades of 1 or greater are noted in the test group;
• Grades of 1 or greater in control group: the response of test animals exceed the most severe reaction in control animals.

Rechallenge recommended:

The number of animals showing a response in test group is greater than that in control group, while the reaction intensity is note greater than that exhibited by the controls.

If you have additional questions about buehler assay or would like to find out more about our services, please feel free to contact us.

Reference

• International Organization for Standardization. Biological evaluation of medical devices — Part 10: Selection of tests for interactions with blood. ISO 10993-10; (2010).