Dimethylsilanediol from silicone elastomers: Analysis, release from biopharmaceutical process equipment, and clearance studies.

Polysiloxanes are considered one of the most important commercial families of synthetic elastomers. They are frequently employed in biopharmaceutical manufacturing equipment as flexible single-use solutions due to superior material properties and compatibility with diverse sterilization methods. Extractables and leachables (E&L) testing is essential in qualifying such equipment, involving extraction studies to assess the potential release of compounds from plastic components for risk assessment. Silicone releases oligomeric siloxanes and small hydrolysis products, with dimethylsilanediol (DMSD) being the main hydrolysis product found in significant concentrations in aqueous process solutions. DMSD presents challenges for analysis, requiring specifically tailored analytical methods to detect it, which are commonly not applied in standard E&L screening tests. In biopharmaceutical manufacturing, it is relevant to consider the potential of DMSD to repolymerize into silicone oil when specific process parameters are altered. This may lead to interactions with drug ingredients, including proteins, resulting in the formation of aggregates. We synthesized and characterized DMSD using X-ray structure analysis and established an HPLC method with a refractive index detector to investigate the release of DMSD from commercially available silicone tubing used in drug manufacturing following autoclaving and irradiation. Subsequently, we assessed typical biopharmaceutical downstream operations for effectively removing this compound from the process stream.

Water loss from silicone tubing and effect on protein concentration during drug product manufacturing.

Silicone tubing is used in various unit operations during drug product (DP) manufacturing. Hold of protein formulations in silicone tubing over time may have an impact on product quality, particularly protein concentration. This study evaluated the change in protein concentration of a test monoclonal antibody (mAb) formulation over various hold times in silicone tubing as a function of tubing internal diameter (ID) and wall thickness. It was hypothesized that the rate of water diffusion through the semi-permeable membrane is a function of the tubing ID and wall thickness. The weight and protein concentration of various formulation-filled tubings over time was measured. The weight of water lost varied linearly with the change in protein concentration. It was observed to be independent of mAb type, formulation composition, and initial protein concentration for a given tubing ID and wall thickness. The effect of formulation water activity on the water loss rate was investigated. A mechanistic diffusion-based model was developed that predicts the change in tubing weight and therefore protein concentration over various hold times for a given formulation and tubing. Overall, this study suggests that water loss from silicone tubing affects protein concentration and should be monitored during DP process development and manufacturing.

Vapor-Phase Hydrogen Peroxide Uptake by Silicone Tubing and Primary Packaging Components during Protein Drug Product Aseptic Filling: Impact of Pretreatment and Sterilization Process.

In the vapor-phase hydrogen peroxide (VPHP)-sanitized environment, VPHP uptake by product-contacting components could eventually lead to undesired oxidation of biological drug products. Silicone tubing and primary packaging materials are prominent examples of such product-contacting surfaces that are typically processed/sterilized prior to use. This study investigated the VPHP-uptake tendency of these components and how their respective processing/sterilization methods affect the uptake behaviors. Silicone tubing that was sterilized via autoclave or gamma irradiation exhibited different VPHP uptake patterns-decreased uptake rates post autoclaving vs. increased uptake rates post gamma irradiation. The reduced uptake tendency of autoclaved tubing is maintained for 14 days after sterilization, whereas the uptake tendency of irradiated tubing was mostly reversed to normal levels 1 month after irradiation. Empty glass vials adsorbed hydrogen peroxide via the diffusion of VPHP into the vial with high vial-to-vial variability. Vial pretreatment (i.e., depyrogenation) and surface hydrophilicity/hydrophobicity impacted the uptake tendency. Stoppers and empty syringes also adsorbed hydrogen peroxide but at a relatively low level. The uptake behavior of these components appeared to correlate with water levels at the surface (i.e., hydrophilicity). This study provides process development scientists and engineers an in-depth understanding of the VPHP uptake by critical product-contacting surfaces so that they can mitigate the impact on drug product quality.LAY ABSTRACT: This study investigated vapor-phase hydrogen peroxide (VPHP) absorption by biopharmaceutical drug products via VPHP uptake by critical product-contacting components during the aseptic manufacturing process with a focus on various pretreatments and processing of these components. Sterilization of silicone tubing by gamma irradiation or autoclaving resulted in different VPHP uptake profiles with different effect durations. Primary packaging components, such as vials, syringes, and stoppers, also showed different levels of VPHP uptake with surface hydrophilicity/hydrophobicity playing a critical role. These outcomes suggested that VPHP uptake is a complex phenomenon and should be carefully considered to minimize its impact on product quality. The approach and outcome of this study can benefit scientists and engineers who develop biological product manufacturing processes by providing an in-depth understanding of drug product process risks.

Comparison of Application of Mitomycin C Vs Silicon Stenting Vs Conventional Method in Endonasal Dacrocystorhinostomy: A Randomized Controlled Trial of 150 Patients.

INTRODUCTION: Since the days of Hippocrates, many modifications have been proposed in endonasal dacrocystorhinostomy (DCR), with the use of new drugs and implants showing variable results. The objective of this study was to analyze whether the use of silicon tubing or mitomycin C administration has an added advantage over conventional endonasal DCR. MATERIALS AND METHODS: A randomized controlled trial of 150 patients between the ages of 6 and 70 years presenting with epiphora was performed. Patients were randomly divided into three groups: endonasal DCR with mitomycin C administration, endonasal DCR with silicon stenting, or conventional endonasal DCR. Patients were followed up on Days 15, 30, 60 and 90 postoperatively for sac syringing to confirm patency. RESULTS: The majority of patients (28.7%) were in the fourth decade of life, with a female predominance (65.3%). Dacrocystitis was most commonly seen in the left eye (58.7%). An intergroup comparison was performed using the Kruskal-Wallis test at the end of 3 and 5 months. The results suggest that the success rate was significantly higher in patients with a silicone stent (P=0.04) as compared with the other two groups, although no significant difference in failure rate was seen between patients on mitomycin C and conventional therapy (P=0.132 at Month 3 and P=0.481 at Month 5, Mann-Whitney U-test). CONCLUSION: Our study shows that silicone tube stenting had a better success rate compared with the other two groups, with no significant statistical difference between the use of mitomycin C and the conventional technique.

Influence of particle shedding from silicone tubing on antibody stability.

OBJECTIVES: Peristaltic pumps are increasingly employed during fill & finish operations of a biopharmaceutical drug, due to sensitivity of many biological products to rotary piston pump-related stresses. Yet, possibly also unit operations using peristaltic pumps may shed particulates into the final product due to abrasion from the employed tubing. It was the aim of this study to elucidate the potential influence of particles shed from peristaltic pump tubing on the stability of a drug product. METHODS: Spiking solutions containing shed silicone particles were prepared via peristaltic pumping of placebo under recirculating conditions and subsequently characterized. Two formulated antibodies were spiked with two realistic, but worst-case levels of particles and a 6-month accelerated stability study with storage at 2-8, 25 and 40°C were conducted. KEY FINDINGS: Regarding the formation of aggregates and fragments, both mAbs degraded at their typically expected rates and no additional impact of spiked particles was observed. No changes were discerned however in turbidity, subvisible and visible particle assessments. Flow imaging data for one of the mAb formulations with spiked particles suggested limited colloidal stability of shed particles as indicated by a similar increase in spiked placebo. CONCLUSIONS: Shed silicone particles from peristaltic pump tubing are assumed to not impair drug product stability.

Preservative loss from silicone tubing during filling processes.

Significant loss of preservative was observed during filling of drug products during filling line stops. This study evaluated the losses of three commonly used preservatives in protein drugs, i.e. benzyl alcohol, phenol, and m-cresol. Concentration losses during static incubation were quantified and interpreted with regard to the potential driving forces for the underlying sorption, diffusion, and desorption steps. Partitioning from the solution into the silicone polymer was identified as the most decisive parameter for the extent of preservative loss. Additionally, the influence of tubing inner diameter, starting concentration as well as silicone tubing type was evaluated. Theoretical calculations assuming equilibrium between solution and tubing inner surface and one-directional diffusion following Fick's first law were used to approximate experimental data. Since significant losses were found already after few minutes, adequate measures must be taken to avoid deviations during filling of preservative-containing protein solutions that may impact product quality or antimicrobial efficacy. As a possible alternative to the highly permeable silicone tubing, a specific make of fluoropolymer tubing was identified being suitable for peristaltic pumps and not showing any preservative losses.

A robust, simple, high-throughput technique for time-resolved plant volatile analysis in field experiments.

Plant volatiles (PVs) mediate interactions between plants and arthropods, microbes and other plants, and are involved in responses to abiotic stress. PV emissions are therefore influenced by many environmental factors, including herbivore damage, microbial invasion, and cues from neighboring plants, and also light regime, temperature, humidity and nutrient availability. Thus, an understanding of the physiological and ecological functions of PVs must be based on measurements reflecting PV emissions under natural conditions. However, PVs are usually sampled in the artificial environments of laboratories or climate chambers. Sampling of PVs in natural environments is difficult, being limited by the need to transport, maintain and provide power to instruments, or use expensive sorbent devices in replicate. Ideally, PVs should be measured in natural settings with high replication, spatio-temporal resolution and sensitivity, and modest costs. Polydimethylsiloxane (PDMS), a sorbent commonly used for PV sampling, is available as silicone tubing for as little as 0.60 € m(-1) (versus 100-550 € each for standard PDMS sorbent devices). Small pieces of silicone tubing (STs) of various lengths from millimeters to centimeters may be added to any experimental setting and used for headspace sampling, with little manipulation of the organism or headspace. STs have sufficiently fast absorption kinetics and large capacity to sample plant headspaces over a timescale of minutes to hours, and thus can produce biologically meaningful 'snapshots' of PV blends. When combined with thermal desorption coupled to GC-MS (a 40-year-old widely available technology), use of STs yields reproducible, sensitive, spatio-temporally resolved quantitative data from headspace samples taken in natural environments.

Outcomes of revision external dacryocystorhinostomy and nasal intubation by bicanalicular silicone tubing under endonasal endoscopic guidance.

AIM: To evaluate the long-term treatment outcomes in patients who underwent revision of external dacryocystorhinostomy (DCR) and nasal intubation by bicanalicular silicone tubing (BSTI) under endonasal endoscopic guidance. METHODS: Data from 28 patients with recurrent dacryocystitis were retrospectively reviewed. Revision external DCR and bicanalicular nasal intubation by silicone tubing under endonasal endoscopic guidance was performed in 28 eyes of 28 patients. The patients were evaluated with respect to the reason of recurrence, time to recurrence, time to revision, duration of follow-up and surgical success. RESULTS: Endoscopic endonasal examination detected an osteotomy-side obstruction by the excessive granulation tissue in 24 patients (86%), nasal septal deviation in three patients (10%) and nasal polyp in one patient (4%). Recurrence occurred after a mean duration of 5.3±3.7 months following the first operation. The mean time between the first DCR operation and the revision DCR was 11.5 ± 9.3 months. After a mean follow-up of 14.9±7.8 months, the rate of anatomic success alone was 85% (24/28); the rate of subjective success was 78% (22/28). CONCLUSION: Revision external DCR and bicanalicular nasal intubation by silicone tubing under endonasal endoscopic guidance can be recommended in patients with recurrent dacryocystitis as a surgical approach that achieves satisfactory objective and subjective success rates.