USP (87) Biological Reactivity Tests, In Vitro (Cytotoxicity)

USP 87 is designed to determine the biological reactivity of mammalian cell cultures following contact with elastomeric plastics and other polymeric materials with direct or indirect patient contact or of specific extracts prepared from the materials under test.

Mammalian fibroblast, L-929, cells are utilized for cell culture in USP. Three test methods may be utilized under USP: Agar Diffusion Test, the Direct Contact Test and the Elution Test. The decision as to which type of test or the number of tests to be performed to assess the potential biological response of a specific sample or extract depends upon the material, the final product and its intended use.

Agar Diffusion Test

This test is designed for elastomeric closures in a variety of shapes. The agar layer acts as a cushion to protect the cells from mechanical damage while allowing the diffusion of leachable chemicals from the polymeric specimens. Extracts of materials that are to be tested are applied to a piece of filter paper.

Grade Reactivity Description of Reactivity Zone
0 None No detectable zone around or under specimen
1 Slight Some malformed or degenerated cells under specimen
2 Mild Zone limited to area under specimen
3 Moderate Zone extends 0.5 to 1.0 cm beyond specimen
4 Severe Zone extends greater than 1.0 cm beyond specimen

Direct Contact Test

This test is designed for materials in a variety of shapes. The procedure allows for simultaneous extraction and testing of leachable chemicals from the specimen with a serum-supplemented medium. The procedure is not appropriate for very low or high-density materials that could cause mechanical damage to the cells.

Elution Test

This test is designed for the evaluation of extracts of polymeric materials. The procedure allows for extraction of the specimens at physiological or non-physiological temperatures for varying time intervals. It is appropriate for high-density materials and dose-response evaluations.

Grade Reactivity Description of Reactivity Zone
0 None Discrete intra-cytoplasmic granules; no cell lysis
1 Slight Not more than 20% of the cells are round, loosely attached, and without Intra-cytoplasmic granules; occasional lysed cells are present
2 Mild Not more than 50% of the cells are round and devoid of intra-cytoplasmic granules; no extensive cell lysis and empty areas between cells
3 Moderate Not more than 70% of the cell layers contain rounded cells or are lysed
4 Severe Nearly complete destruction of the cell layers

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