BRIEFING

 〈208〉 Anti-factor Xa and Anti-factor IIa Assays for Unfractionated and Low Molecular Weight Heparins.

 This proposal is based on the version of the chapter official as of August 1, 2020. To enhance clarity of the chapter, the Biologics Monographs 3—Complex Biologics & Vaccines Expert Committee proposes to revise the following sections and to introduce new text with the following changes:

1. Revise the Introduction.

2. Add a General Considerations section to provide additional information on important areas to consider when performing the assays such as reagent quality, reagent lot and batch changes, temperature control, timing, the use of blanks and statistical model considerations.

3. Revise the tests for Anti-Factor Xa Activity for UFH, Anti-Factor IIa Activity for UFH, Anti-Factor Xa Activity for LMWH, and Anti-Factor IIa Activity for LMWH.

4. Update the antithrombin, factor Xa, and thrombin reagents to indicate the species of the proteins.

5. Revise the preparation of the pH 8.4 buffer in Anti-Factor Xa Activity for UFH to allow flexibility in the reagents used.

6. Rename Thrombin human solution to Human thrombin solution and increase the specific activity to 2000 IU/mg in Anti-Factor IIa Activity for UFH. Add the specific activity of NLT 2000 IU/mg for Human thrombin solution in Anti-Factor IIa Activity for LMWH.

7. Add language to the Stopping solution to allow for alternative acids if they are validated and lower the required concentration to 2%.

8. Add a Note to the Analysis sections of all of the test methods to clarify the use of blanks.

9. Add endpoint and kinetic instructions in Anti-Factor Xa Activity for UFH to harmonize with the instructions in the Anti-Factor IIa Activity for UFH test.

10. Add and harmonize system suitability requirements for all assays.

11. Add an alternative diluent to the preparations for Human antithrombin solution and Human thrombin solution in Anti-Factor Xa and Anti-Factor IIa Assays for Low Molecular Weight Heparin.

12. Revise the Calculations sections of all tests to provide options of using the Slope ratio assay or the Parallel-line assay for the statistical analysis to calculate the potency.

13. Remove the acceptance criteria from all tests as this information will be included in the individual monographs that cite this chapter.

 Additionally, minor editorial changes have been made to update the chapter to current USP style.

 (BIO3: R. Potts)

 Correspondence Number—C314767