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J Pharm Sci. 2015 Jun;104(6):1938-1945. doi: 10.1002/jps.24424. Epub 2015 Mar 21.

The "New Polyethylene Glycol Dilemma": Polyethylene Glycol Impurities and Their Paradox Role in mAb Crystallization.

Author information

1
Department of Pharmacy, Pharmaceutical Technology and Biopharmaceutics, Ludwig-Maximillians-University Munich, Munich D-81377, Germany. Electronic address: Christian.Hildebrandt@cup.uni-muenchen.de.
2
Department of Pharmacy, Pharmaceutical Technology and Biopharmaceutics, Ludwig-Maximillians-University Munich, Munich D-81377, Germany.
3
NBE Formulation and Process Sciences, Drug Product Development, AbbVie GmbH and Company KG, Ludwigshafen D-67061, Germany.

Abstract

Polyethylene glycols (PEG) represent the most successful and frequently applied class of excipients used for protein crystallization. PEG auto-oxidation and formation of impurities such as peroxides and formaldehydes that foster protein drug degradation is known. However, their effect on mAb crystallization has not been studied in detail before. During the present study, a model IgG1 antibody (mAb1) was crystallized in PEG solutions. Aggregate formation was observed during crystallization and storage that was ascribed to PEG degradation products. Reduction of peroxide and formaldehyde levels prior to crystallization by vacuum and freeze-drying was investigated for its effect on protein degradation. Vacuum drying was superior in removal of peroxides but inferior in reducing formaldehyde residues. Consequently, double purification allowed extensive removal of both impurities. Applying of purified PEG led to 50% lower aggregate fractions. Surprisingly, PEG double purification or addition of methionine prior to crystallization prevented crystal formation. With increased PEG concentration or spiking with peroxides and formaldehydes, crystal formation could be recovered again. With these results, we demonstrate that minimum amounts of oxidizing impurities and thus in consequence chemically altered proteins are vital to initiate mAb1 crystallization. The present study calls PEG as good precipitant for therapeutic biopharmaceuticals into question.

KEYWORDS:

crystallization; formaldehydes; freeze-drying; peroxides; polyethylene glycol (PEG); polymer chemical degradation; protein aggregation; proteins; vacuum drying

PMID:
25808186
DOI:
10.1002/jps.24424
[Indexed for MEDLINE]

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