Considerations for the Terminal Sterilization of Oligonucleotide Drug Products

Abstract

A primary function of the parenteral drug product manufacturing process is to ensure sterility of the final product. The two most common methods for sterilizing parenteral drug products are terminal sterilization (TS), whereby the drug product is sterilized in the final container following filling and finish, and membrane sterilization, whereby the product stream is sterilized by membrane filtration and filled into presterilized containers in an aseptic processing environment. Although TS provides greater sterility assurance than membrane sterilization and aseptic processing, not all drug products are amenable to TS processes, which typically involve heat treatment or exposure to ionizing radiation. Oligonucleotides represent an emerging class of therapeutics with great potential for treating a broad range of indications, including previously undruggable targets. Owing to their size, structural complexity, and relative lack of governing regulations, several challenges in drug development are unique to oligonucleotides. This exceptionality justifies a focused assessment of traditional chemistry, manufacturing, and control strategies before their adoption. In this article, we review the current state of sterile oligonucleotide drug product processing, highlight the key aspects to consider when assessing options for product sterilization, and provide recommendations to aid in the successful evaluation and development of TS processes. We also explore current regulatory expectations and provide our interpretation as it pertains to oligonucleotide drug products.

Keywords: autoclave; degradation; drug product; formulation; oligonucleotide; terminal sterilization.

FIG. 1.

EMA decision tree for sterilization choices for aqueous products. EMA, European Medicines Agency.

FIG. 2.

Terminal sterilization development paradigm for aqueous oligonucleotide products.

FIG. 3.

Common degradation products for antisense oligonucleotides.

FIG. 4.

The effect of formulation buffer on the stability of a model oligonucleotide during terminal sterilization at 115°C for 15 min.

FIG. 5.

Probability of drug product failing the lower assay limit of 95% due to Degradation (Deg) during Terminal Sterilization (RSD = Relative Standard Deviation).

FIG. 6.

Internal container pressure of a 1 mL PFS filled with 0.65 mL fill volume and 0.1 mL head space as a function of temperature. PFS, prefilled syringes.

FIG. 7.

Worst-case theoretical plunger movement in a 1 mL PFS with 0.65 mL fill volume when sterilized at 121°C at varying support pressures. The different traces show the impact of having head space volumes of 0.1, 0.2, or 0.3 mL.