Biological Reactivity of Materials – USP <88>

Elastomerics, plastics or other polymeric materials with direct or indirect patient contact should be tested for adverse effects. Extracts of the materials are prepared and injected into a rodent species. The animals are monitored for any systemic or local responses. Many factors could influence the suitability of the material for a specific use. Materials composition, processing and cleaning procedures, inks, adhesives, adsorption and permeability of preservatives, sterilization method and conditions of storage could affect the performance of the material.

There are three in vivo tests involved in the classification of plastics.  The Systemic Injection Test and the Intracutaneous Test are designed to determine the systemic and local biological responses to plastics and other polymers by the single-dose injection of specific extracts prepared from a sample.  The third test, the Implantation Test, is designed to evaluate the reaction of living tissue to a test material. The testing for the six different class plastics levels is all done using different combinations of these three tests and different extracts.

USP Class Plastics

USP class plastic tests are designed to assess the biological reactivity of various types of plastics materials in vivo. Originally developed to test drug containers, the class plastics tests are often performed on unmolded plastic resins as well as containers. Class plastics testing is not a substitute for medical device biocompatibility testing, medical device materials are recommended to follow ISO guidelines, but biological reactivity class plastics testing is often used by manufacturers to classify materials.

Class VI Plastic Certificate

The USP defines six plastics classes, from I to VI (VI being the most strict). Therefore, many plastics manufacturers find it advantageous to have their plastic resins certified as USP Class VI, especially if the resin is a likely candidate to be used in medical devices. A plastic resin material that has passed Class VI certification is assumed to be more likely to produce favorable biocompatibility results. PBL provides of certificate of analysis for all materials test at PBL that pass the USP Class VI specifications.

Biological Reactivity Testing Services

  • USP <88> Systemic Injection Test
  • USP <88> Intracutaneous Test
  • USP <88> Implantation Test

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