Levocarnitine Monograph Revision: Proposed Direct Chiral HPLC Method

USP Compendial Notices

Published March 27th, 2026

Detected March 27th, 2026

Summary

The USP has proposed a direct chiral HPLC method to revise the Enantiomeric Purity test in the Levocarnitine monograph due to the temporary unavailability of the required derivatization reagent (+)-FLEC. This proposed method is currently open for public comment.

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What changed

The United States Pharmacopeia (USP) has issued a notice regarding the Levocarnitine monograph, specifically addressing the Enantiomeric Purity test. Due to the commercial unavailability of the required reagent (+)-1-(9 Fluorenyl)ethyl chloroformate ((+)-FLEC), which is expected to last several months, USP is proposing a direct chiral High-Performance Liquid Chromatography (HPLC) method as an interim revision. This proposed method is detailed in PF 52(2) and is currently available for public comment.

Laboratories unable to perform the current monograph procedure due to the reagent shortage should note this proposed revision. The USP will monitor the reagent supply and may consider further actions if the interruption persists. Compliance officers for drug manufacturers should review the proposed method in PF 52(2) and consider submitting comments by the deadline indicated in that publication to influence the final monograph revision.

What to do next

Review the proposed direct chiral HPLC method for the Levocarnitine monograph in *PF* 52(2).
Consider submitting comments on the proposed method revision by the deadline in *PF* 52(2).
Monitor USP communications regarding the availability of (+)-FLEC and potential further actions.

Source document (simplified)

Levocarnitine

Type of Posting: General Announcement
Posting Date: 27-Mar-2026
Expert Committee: Non-Botanical Dietary Supplements

USP has received multiple reports indicating that derivatization reagent (+)-1-(9 Fluorenyl)ethyl chloroformate ((+)-FLEC), which is required to perform the Enantiomeric Purity test in the currently official Levocarnitine monograph, is temporarily unavailable from all known commercial suppliers. Its availability is not expected for several more months, which leaves many laboratories unable to perform the monograph procedure as written.

In the interim, the Non-Botanical Dietary Supplement Expert Committee would like users to be aware that USP has proposed a direct chiral HPLC method to revise the the Enantiomeric Purity test in the Levocarnitine monograph. This proposed method is currently available for comment in PF 52(2).

USP will continue to monitor the supply status of (+)-FLEC and its impact on compendial compliance. If the supply interruption persists, USP may consider additional actions.

Should you have any questions, please contact Fatkhulla Tadjimukhamedov, Senior Scientist (FKT@usp.org).