Observation and Mitigation of Lamellar Silica Particles Formed in Pharmaceutical Products Packaged in Glass Vials

A new type of lamellae-like particles was observed in protein based liquid therapeutic protein drug product (DP) packaged in standard (STD) and delamination controlled (DC) Type IB glass vials stored at 2-8°C as early as two weeks after manufacture. These particles were determined to be remarkably different from lamellae in not only in their chemical composition, but in the mechanism by which these are formed. The lamellae-like particles were an ultra-thin (< 200 nm) film, appeared curled, sheet-like, folded with no defined edges identified as lamellar silica composed of silica and polysorbate 80 (PS 80). It was also observed that the lamellar silica particles, when formed in a given drug product lot, not only were observed in a small percentage of vials, but also remained at low (≤ 5) numbers in affected vials, often decreasing in number over time. This is in contrast to the large number of commonly reported glass lamellae (hundreds per vial) observed in vials prone to delamination with a glass vial interior showing a delaminated inner surface. In this case study, evidence from low Si leachable levels in solution and various surface analytical techniques supported the conclusion that there was neither delamination nor early signs of glass delamination like reaction zones occurring in those impacted vials, regardless. A mechanism for particle formation was hypothesized and experimentally confirmed. Lamellar silica particles are composed of an admixture of condensed silica and PS 80 deposited on the interior walls of glass vials, which form and may be released into solution over time. The root cause was determined to be conditions present during preparation of the vials for drug product filling, specifically the vial washing and depyrogenation steps. These conditions are known to make glass vials prone to delamination; in this case study, they resulted in interactions between the glass and PS 80 present in the formulation. Incomplete drying of the glass vials during depyrogenation in closed ovens was confirmed as the contributing factors that led to lamellar silica particle formation via the studies of silicate spiked into the DC Type IB glass vials filled with the mAb DP in which lamellar silica particles were observed. Prevention of lamellar silica particles formation was successfully achieved through optimization of the duration and pressure of air blow during the vial washing and drying process in a depyrogenation oven. This was evidenced by the lack of appearance of the lamellar silica particles over 48 months for the DP lots filled post optimization. Additionally, the formation of lamellar silica was also mitigated by changing the vial washing process from a closed oven process to a tunnel process, which allowed for improved air flow and hence better drying of the vial primary container.