(W0930-01-05) Assessment of Phenol and Benzyl Alcohol for Use as Preservatives in mAb Drug Therapies

Purpose: Various antimicrobial preservative agents have been used in marketed biologics but rarely in monoclonal antibodies (mAb). To close this gap, we assessed the impact of typical antimicrobial preservatives on stability of the liquid formulations of several mAbs. Preservatives were assessed by being spiked into five formulated drug substance (FDS) formulations with stability of the resulting formulations assessed at different temperatures over time.

Methods: We initially assessed the compatibility of chlorobutanol, m-cresol, phenol and benzyl alcohol with our mAb formulations. It was found that chlorobutanol and m-cresol were not compatible with the assessed formulations so only phenol (3 mg/ml) and benzyl alcohol (10 mg/ml) were tested further. Long-term stability of preservative-spiked formulations was tested in a variety of conditions (5°C, 25°C/60%RH, 40°C/75%RH and 45°C). The critical quality attributes were tested including solution clarity by UV absorbance at 405 nm, subvisible particle formation by MFI, aggregate formation using SE-UPLC, protein concentration using RP-UPLC and protein charge variants using CEX. We are using compendial assays (USP NF < 51 >) to evaluate antimicrobial effectiveness of preservatives.

Results: We found that stability of all formulations of mAbs in the presence of preservatives was preserved at 5°C and 25°C for up to 12 months as determined by the methods listed above (Fig. 1). At the stress conditions (40 and 45 °C), however, preservatives increased mAb aggregation as detected by SE-UPLC in some of the formulations (Fig. 1). Effect of preservatives on mAb aggregation depended on the nature of mAb, preservative and mAb concentration. Preservatives did not influence protein charge or subvisible particle formation even in stress conditions. Effectiveness of the preservatives in reducing microbial activity in these formulations is being evaluated.

Conclusion: Both phenol and benzyl alcohol can be added as preservatives to mAb liquid formulations without disrupting their stability at the storage conditions. These preservatives didn’t interfere with mAb stability in storage conditions. Their effect in stress conditions depended on preservative identity, mAb identity and mAb concentration. These results indicate that mAb stability at stress conditions needs to be evaluated for each individual formulation prior to the preservative selection.

References: 1) Meyer BK, Ni A, Hu B, Shi L. Antimicrobial preservative use in parenteral products: past and present. J Pharm Sci. 2007 Dec;96(12):3155-67. doi: 10.1002/jps.20976. PMID: 17722087.
2) Michael J. Akers. Sterile Drug Products Formulation, Packaging, Manufacture, and Quality. Drugs and the Pharmaceutical Sciences. Informa Healthcare. 2010.

Acknowledgements:Conflict of interest: All authors are employees of Regeneron Pharmaceuticals.

No substantial effect of preservatives on HMW formation was observed at 25° C for mAb A

No substantial effect of preservatives on HMW formation was observed at 25° C for mAb B

Preservatives increased HMW formation from mAbs under stress conditions depending on the protein and preservative identity and protein concentration. For example, increased HMW formation at 40°C was observed for mAb A and C but not for mAb B.