Excipient impurities like formaldehyde and PLGA degradation products can react with liraglutide's N-terminal histidine, creating unwanted interaction products that formulation scientists must account for.
3 interaction product typesImidazopyrimidine, glycolyl, and lactolyl modifications formed from excipient impurities reacting with liraglutide
What the researchers found
N-terminal histidine of liraglutide reacts with formaldehyde impurities in excipients and PLGA degradation products, forming imidazopyrimidine, glycolyl, and lactolyl interaction products.
Why it matters
Peptide drug stability is critical for patient safety and drug efficacy. If excipient impurities silently modify the active peptide, it could reduce potency or create potentially immunogenic degradation products. This study highlights a previously underappreciated source of instability.
The numbers in context
Formaldehyde reported as impurity in PEG, glycerol, magnesium stearate, microcrystalline cellulose, and mannitol.
How the study worked
Excipient compatibility study using LC-HRMS, MS/MS, and hydrogen-deuterium exchange mass spectrometry to identify and characterize peptide-excipient interaction products during liraglutide formulation development.
Who was studied
Pharmaceutical formulation compatibility analysis
What this study cannot tell us
Focused solely on liraglutide and its specific excipient combinations. The clinical significance of the interaction products (e.g., whether they affect efficacy or safety) was not evaluated. Did not assess whether these interactions occur at levels that would affect commercial products.
How to read the evidence
Preliminary evidence from in vitro formulation chemistry studies. Findings are analytical observations without clinical outcome data.
When this study was published
Published in 2024. Addresses ongoing challenges in peptide formulation science.
The bigger picture
As peptide therapeutics become more common, understanding all sources of drug degradation becomes essential. This study shows that even "inactive" ingredients can actively degrade peptide drugs, and that the N-terminal histidine residue — present in many therapeutic peptides — is particularly vulnerable.
Questions still open
- Do these interaction products form at clinically significant levels in marketed liraglutide formulations?
- Are other histidine-containing therapeutic peptides similarly affected by excipient impurities?
- Can excipient purification or alternative excipients eliminate these interactions?
Common questions
Does this mean liraglutide products on the market are unsafe?
Why is the N-terminal histidine so reactive?
Read the original research
Reactivity of N terminal histidine of peptides towards excipients/impurity of excipients: A case study of liraglutide excipient compatibility study.
Journal of pharmaceutical sciences, 113(11), 3246-3254
Citation
Sheikh, Azahar R; Vitore, Jyotsna G; Bhalekar, Vijay S; Jain, Sonali; Kukreja, Divya; Giri, Tushar; Sharma, Nitish; Benival, Derajram; Shah, Ravi P. (2024). Reactivity of N terminal histidine of peptides towards excipients/impurity of excipients: A case study of liraglutide excipient compatibility study.. Journal of pharmaceutical sciences, 113(11), 3246-3254. https://doi.org/10.1016/j.xphs.2024.08.007