BRIEFING

 dl-Lactide and Glycolide (85:15) Copolymer 23000 Hexanediyl Ester. Because there is no existing NF monograph for this excipient, a new monograph based on validated methods of analysis is being proposed. Please see the background information for developing the monographs for lactide-glycolide and lactic acid-glycolic acid polymers (PLGs and PLGAs), including this monograph, in the Stimuli article A Practical Approach to Compendial Nomenclature and Testing For Lactide and Glycolide Polymers and Related Polymeric Excipients, which appeared in PF 48(2). The first three PLG monographs have been official since May 2025: dl-Lactide and Glycolide (50:50) Copolymer 12000 Acid, dl-Lactide and Glycolide (50:50) Copolymer 12000 Ethyl Ester, and dl-Lactide and Glycolide (50:50) Copolymer 46000 Acid. The fourth PLG monograph for dl-Lactide Homopolymer 14000 Acid will become official in April 2026. The proposals for the fifth and sixth: dl-Lactide and Glycolide (50:50) Copolymer 63000 Acid and dl-Lactide and Glycolide (75:25) Copolymer 20000 Acid, were published in PF 51(4) in July 2025. This proposal represents the seventh PLG monograph developed at USP.

 Nomenclature is essential for accurately representing the composition of PLGs/PLGAs. The USP Nomenclature Expert Panel has recommended the monograph title based on excipient information from FDA-approved drugs that utilize this excipient.

 This excipient is synthesized via an open-ring polymerization route. Based on the sponsor’s submission, the proposal includes tests for critical quality attributes such as monomer ratio, end group, residual catalyst, residual monomers, etc. It also incorporates a viscosity test, which is widely used in the industry to differentiate various types of PLGs/PLGAs. For molecular weight determination, please refer to USP general chapters Nuclear Magnetic Resonance Spectroscopy Number-Average Molecular Weight Determination for Lactide-Glycolide Polymers with Ester End Groups 〈315〉 and Size Exclusion Chromatography Molecular Weight and Polydispersity Determination for Lactide-Glycolide Polymers Using Universal Calibration 〈316〉. These two stand-alone chapters provide methodologies for molecular weight determination for PLGs, with 〈316〉 also covering polydispersity measurement.

 (EXC2: P. Zhang)

 Case ID—SUB-2836