Short Peptides as Excipients in Parenteral Protein Formulations: A Mini Review

Abstract

Biopharmaceutical medicines represent one of the most dynamic sectors of the pharmaceutical industry, with therapeutic proteins forming the largest and most important group. Their structural complexity and inherent sensitivity to chemical and physical stressors, however, continue to pose major challenges for formulation development and long-term stability. Short peptides have emerged as a promising yet underutilized class of excipients for protein-based drug products. Their modular architecture allows for precise tuning of physicochemical properties such as polarity, charge distribution, and hydrogen-bonding potential, thereby offering advantages over single amino acids. Experimental studies indicate that short peptides can serve multiple functions: stabilizers, antioxidants, viscosity-lowering agents, and as lyo/cryoprotectants or bulking agents in lyophilized formulations. Notably, the relatively small and chemically defined space of short peptides—approximately 400 possible dipeptides and 8000 tripeptides—makes them particularly amenable to systematic screening and computational modeling. This enables rational identification of candidates with tailored excipient functions. This review summarizes current knowledge on the use of short peptides as excipients in parenteral protein formulations, with a focus on their functional versatility and potential for rational design in future development.

Introduction

Biopharmaceutical medicines constitute a significant, fast-growing sector of the pharmaceutical industry [1]. Specifically, this group of modern and dynamically developing therapeutics accounted for half of the best-selling drugs of 2020 [2]. Furthermore, the loss of patent protection and exclusivity rights of many biological medicines allows biosimilar medicines to enter the market. Hence, a significant interest in the production of cheaper, off-patent counterparts to already approved biological medicines has been observed among pharmaceutical companies. As a result of health care cost reduction, the biosimilar market will provide a substantial contribution to an increase in access to innovative therapies for patients [3]. One of the largest groups of biologicals is therapeutic proteins. Development of drug products based on the abovementioned molecules is challenging, because proteins, due to their structural complexity, are characterized by an enhanced susceptibility to various environmental factors [4,5].

Nearly all commercially available protein-based drugs are formulated as solutions or lyophilizates for parenteral administration [6]. Their degradation can occur during manufacturing, processing, storage, and administration to the patient. This is common in both liquid and solid preparations. The extent of degradation depends on factors such as the amino acid sequence, isoelectric point, and hydrophobicity of the molecule, as well as storage temperature, primary packaging, and the composition of the medicinal product. Degradation products may reduce the drug activity and, in the worst case, increase its immunogenicity. Therefore, the primary goal of formulation (i.e., a carefully selected combination of excipients) is to ensure protein stability so that the medicinal product remains effective and safe for patients throughout its entire intended shelf-life.

As mentioned above, many degradation pathways are strongly dependent on the pH and ionic strength (composition) of the solution. While it is nearly impossible to completely prevent all degradation routes, selecting appropriate excipients can minimize them to an acceptable level [7,8].

Up to date, several review articles regarding excipients utilized in therapeutic protein formulations have been published. As an example, Kamerzell et al. comprehensively compiled excipient categories, protein–excipient interaction mechanisms, as well as biophysical methods utilized to study them [9]. Another interesting example is an article written by Strickley et al., where authors reviewed formulations of commercially available antibodies [10]. Lastly, Bjelošević et al. defined the most important groups of biopharmaceutical excipients utilized in lyophilized presentations [11]. Because our article is mainly focused on latest achievements in excipient group of short peptides, general information on parenteral protein-related excipients was reduced to basic concepts. In order to acquaint oneself with those topics in a more detailed manner, reference to aforementioned publications is advised. A concise overview of excipient categories, classified according to their functional roles in the development and stabilization of parenteral protein therapeutics, is provided in Table 1.

Table 1. Excipients utilized in parenteral protein formulations [12]. Several excipients have dual or multiple roles and, therefore, appear in more than one category.

Short peptides, particularly dipeptides and tripeptides, have emerged as a promising but underutilized class of excipients for parenteral protein formulations. Their modular structure allows for the precise tuning of physicochemical properties such as polarity, charge distribution, and hydrogen bonding capacity, offering more formulation flexibility than individual amino acids. As an example, short peptides have shown potential to act as stabilizers, viscosity reducers, antioxidants, cryoprotectants, and bulking agents in both liquid and lyophilized protein formulations (Figure 1). Moreover, the relatively small and chemically defined space of di- and tripeptides (~400 and ~8000 possible combinations, respectively) makes them amenable to systematic experimental screening or computational modeling strategies aimed at identifying peptide-based excipients with tailored functional profiles [13]. Together, these attributes position short peptides as a versatile and rationally designable platform for next-generation excipient development in protein drug formulations.

Figure 1: Examples of short peptides explored as excipients in protein formulations, illustrating their potential functional roles

This review focuses on the latest achievements in the application of short peptides as excipients in parenteral protein formulations, highlighting their functional roles, mechanisms of action, and formulation contexts—both in solution and in lyophilized products. A particular emphasis is placed on their potential as a rationally designable excipient class for future formulation development.

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Migoń, D.; Jaremicz, Z.; Kamysz, W. Short Peptides as Excipients in Parenteral Protein Formulations: A Mini Review. Pharmaceutics 2025, 17, 1328. https://doi.org/10.3390/pharmaceutics17101328

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