Characterization of Peptide-Preservative Interaction and Reversibility by NMR Spectroscopy

Incretin-based therapies have emerged as successful antiobesity medications capable of safely achieving sizable and sustained body weight loss; however, factors such as cost and patient access must be addressed in order to maximize their global impact. A multiple-dose preserved formulation, introduced as a reformulated product after its single-dose nonpreserved counterpart secures the initial regulatory approval, may address some of these challenges. In the current study, we employed 1D and 2D NMR to investigate the interactions between a model therapeutic incretin peptide and antimicrobial preservatives, i.e., benzyl alcohol and phenol. Our findings indicate that benzyl alcohol does not interact or otherwise significantly affect the model peptide, while phenol binds to the peptide and induces spectral perturbations. Furthermore, our results demonstrate that the changes caused by preservative interaction are fully reversed after the removal of the preservative. Such reversibility is crucial for understanding the potential impact to the pharmacokinetics and pharmacodynamics (PK/PD) profile after the product reformulation. Additionally, the stability and potency of the drug product were further evaluated with analytical techniques including HPLC and cell-based bioassays. The results demonstrate that despite the interaction observed by NMR, the stability and bioactivity of the model peptide remain essentially unchanged in the preserved formulation compared to the nonpreserved formulation, ensuring the therapeutic efficacy of the drug product. Learnings gleaned from these nonclinical laboratory studies are crucial in derisking any clinical bioequivalence studies needed in support of the drug product composition changes.