Protein drug delivery: current dosage form profile and formulation strategies

Protein drugs present specific challenges to the maintenance of long-term stability, which can be accomplished by altering parameters of obtention, purification, molecule structure and formulation. As we believe, commercial formulations are undervalued; therefore, this review focuses on screening, categorising and discussing all formulations of protein drugs approved and not withdrawn by regulatory agencies from United States, Canada and Europe until mid-2018. Peptides (<50 amino acids) were not included to allow a more precise evaluation of choices for larger molecules. We extracted data from the DrugBank database, cross-checked it with the FDA purple book and supplemented it with patient information leaflets and papers. We further classified and discussed the entries according to protein function, drug delivery, route of administration and types of excipient (freeze-dried forms). In addition, alternative choices of excipients were discussed. Experimental work included here relates to targeting strategies with verified pharmacokinetics or in vivo effectiveness to identify physiologically relevant options. Although no single rule can be set for efficient protein formulation, our data help to better understand and optimise the choice for excipients and pharmaceutical dosage forms. For more information, see the Supplemental Data.