Which form of glutamine supplementation improves physical compatibility and stability for admixture in PN solutions?

• A. Free glutamine
• B. Glutamine dipeptide
• C. L-glutamine powder
• D. Protein bound glutamine

Answer: (B)

Glutamine stability in parenteral nutrition solutions is the factor being tested. Free L-glutamine is unstable in PN admixtures—it’s poorly soluble and degrades under typical storage and infusion conditions, which can lead to precipitation, changes in color, and loss of potency. The dipeptide form, glutamine dipeptide, addresses these issues because it is highly soluble and chemically more stable within the solution’s usual pH range and storage temperatures. In the bloodstream, this dipeptide is readily cleaved by peptidases to release glutamine gradually, providing a reliable supply without the instability problems seen with the free amino acid. This combination of improved in-solution stability and efficient in vivo conversion makes glutamine dipeptide the best choice for improving physical compatibility and stability of PN admixtures. Protein-bound glutamine isn’t available as free glutamine in a way that reliably supports PN stability, and free glutamine or L-glutamine powder pose the stability challenges described.