Development of an efficient purification method for a peptide pharmaceutical – Optimisation of HPLC separation and considerations for scaling up to production scale in case of the GLP-1 receptor agonist liraglutide
A successful process development for preparative chromatography demands in-depth knowledge of the parameters involved. An example of a 6-step optimisation procedure is presented for the purification of liraglutide by RP-HPLC. The respective parameters of each optimisation step are illustrated and discussed individually. For the given application, a target purity of 99.5%, with a theoretical yield of 71.5% can be achieved for pilot-scale chromatography with a 3 mL injection volume. In addition, factors which have to be considered for further scale-up into the production scale are presented and discussed.
The history of peptide APIs began in the 1950s, with liquid phase peptide synthesis (LPPS). Using this classic technique, the first pioneering works created the first synthetic, bioactive peptides such as oxytocin (1). Significant further contributions include the solid phase peptide synthesis technique (SPPS) by Merrifield in the 1960s. This innovation improved the recoveries of the individual synthesis cycles up to 99.5%, effectively enabling the synthesis of longer peptides with acceptable, overall yield (2).
Further evolution of the latter technique now theoretically enables the preparation of peptides that comprise more than 100 amino acids (and are therefore already counted as proteins). In practice however, this is usually facilitated by the coupling of previously synthesised smaller peptides (3). An example of the associated difficulties which increase with each additional synthesis step is solvent consumption.
Such aspects have driven the search for alternative peptide production pathways in contrast to LPPS and SPPS. One such pathway tha ...