21 CFR 610.13(b)

Under 21 CFR § 610.13(b), each lot of a licensed biological product intended for injection must be tested for pyrogenicity prior to release using the Rabbit Pyrogen Test (USP <151>), unless an alternative, validated method is approved under § 610.9 (e.g., Bacterial Endotoxins Test, USP <85>).

Purpose: Prevent patient reactions such as fever, chills, or shock caused by pyrogens, primarily bacterial endotoxins.

Mandatory Lot Release Testing: Each lot must undergo pyrogen testing unless a validated alternative is approved.

Official Method:

Rabbit Pyrogen Test (USP ]<151>): Intravenous injection into rabbits with temperature monitoring.

Alternative Methods (§ 610.9):

Bacterial Endotoxins Test (BET, USP <85>): LAL-based assay widely adopted due to higher sensitivity, specificity, and speed, as well as avoidance of live animal use.

BET detects endotoxins only; if non-endotoxin pyrogens are a concern and BET cannot be validated, the rabbit test may still be required.

Acceptance Criteria:

RPT: Passes if temperature rises remain below specified thresholds.

BET: Passes if endotoxin levels are below the product-specific allowable limit defined in USP <85>.

European pharmacopeial texts have removed the RPT; U.S. CFR has not (the eCFR still contains RPT language).