ABSTRACT
The selection of quality excipients is a crucial step in peptide formulation development. Apart from excipient incompatibility, process-related impurities or degradants of an excipient can interact with peptide-active pharmaceutical ingredients, forming the interaction products. The formaldehyde has been reported as an impurity of excipient in polyethylene glycol, glycerol, magnesium stearate, microcrystalline cellulose, mannitol, etc. The peptide contains various amino acids such as histidine, lysine, and arginine having free amine groups. These amine groups act as strong nucleophile and can increase the reactivity of peptides. PLGA is the most widely used biodegradable polymer in sustained-release formulations. The hydrolysis of PLGA generates glycolic acid and lactic acid impurities, which can form the interaction product with the amines of peptides. During the formulation development of Liraglutide, we have found few interaction products. The systematic characterization and mechanistic understanding of these interaction products lead us to imidazopyrimidine, glycolyl, and lactolyl moieties. These interaction products have been characterized thoroughly with the use of LC-HRMS, MS/MS, and hydrogen-deuterium exchange mass studies. The study revealed that the reactivity of N-terminal histidine must be considered for formulation development. Moreover, the quality of excipients with respect to presence of impurities must be considered as critical material attributes.
ABSTRACT
As per the United States Food and Drug Administration, any polymer/chain composed of 40 or fewer amino acids is called a peptide, where more than 40 amino acids are considered proteins. On many occasions, there is a change in the source of manufacturing of the peptide active pharmaceutical ingredient, where one has to prove the sameness of that product with the existing formulation by considering several aspects like the presence of impurities/degradation products, the extent of aggregations, and so forth. For the same, several chromatographic characterization techniques such as reversed-phase high-performance liquid chromatography-ultraviolet/high-resolution mass spectrometry, supercritical fluid chromatography, size-exclusion chromatography, ion-exchange chromatography, and so forth, are widely used in the pharmaceutical industry. It is well known that the method development of peptide molecules is often challenging as many variables are to be kept in mind which can affect the separation, recovery, and stability of the molecule. The present review focuses on the basics of peptide degradation and method development by using various chromatographic techniques for characterization. It also covers a deep insight of method development parameters and variables to be considered which might directly or indirectly affect the chromatographic separation and recovery and also provides a guide on the selection of chromatographic parameters.