Proposal for new USP Chapter <318> NMR Monomer Ratio Determination for Lactide-Glycolide Polymers

In Pharmacopeial Forum 51(4), the USP proposes a new General Chapter <318> titled Nuclear Magnetic Resonance Spectroscopy Monomer Ratio Determination for Lactide–Glycolide Polymers. Developed by the Excipients Test Methods Expert Committee, the chapter introduces a validated proton NMR method to quantify the monomer ratio in ring-opening copolymers of DL- or L-lactide and glycolide.

These polymers are widely used as excipients in complex formulations, but their characterization remains challenging due to the lack of standardized methods. The new chapter aims to support more consistent quality control and regulatory evaluation. It complements three existing monographs and may be expanded in future revisions.

The initiative builds on the General Chapter Prospectus published by USP in October 2024. As no public comments were received at that stage, the full chapter proposal is now open for public review and comment until 30 September 2025.

The draft is available for free on the Pharmacopoeial Forum website. Registration is required but free of charge.