Agitation of the syringe and release of silicone oil

[Translated article] Syringes for intraocular administration: A systematic review

OBJECTIVE

The off-label use in clinical practice of non-approved syringes for intravitreal drug administration has resulted in the detection of silicone oil drops in the vitreous of some patients. This situation derives from the lack of approved syringes for intraocular use in the Spanish market. The aim of this work is to review the use of syringes for intraocular administration, as well as to search for alternatives that meet the legal requirements for these unmet needs.

METHOD

A systematic review was performed following the PRISMA 2020 guidelines by searching PubMed with the descriptors: (silicone) AND (syringes) AND ((intraocular) OR (intravitreal)) and filtering all existing publications from January 2006 to December 2023, including all those articles dealing with silicone oil release in intravitreal injections and analysing the possible consequences.

RESULTS

Sixty-eight results were found, 23 of which were excluded because they did not deal with the subject under study, leaving a total of 45 articles for the systematic review. These were classified according to the conclusions obtained in 4 groups: the adverse reactions produced by silicone; the administration technique; the physicochemical aspects of silicone release; and the characteristics of the medical device. After reviewing the current manufacturers and technical data sheets of commercialised syringes, the existing syringes for this use have been collected, finding 2 that will probably be commercialised in Spain at the beginning of 2024: Zero Residual™ 0.2 ml SiO-free and VitreJect® Ophthalmic.

CONCLUSIONS

From the results obtained, it can be interpreted that the use of syringes and needles with silicone for intravitreal use is a concern for health professionals due to the implications and consequences that may arise in patients, the most important being adverse reactions, so it is necessary to have silicone-free syringes on the market that are specific for intraocular use. Safety and legality in the use of intraocular syringes and needles is essential to guarantee ocular integrity and patient health.

Syringes for intraocular administration: Systematic review

OBJECTIVE

The off-label use in clinical practice of non-approved syringes for intravitreal drug administration has resulted in the detection of silicone oil drops in the vitreous of some patients. This situation derives from the lack of approved syringes for intraocular use in the Spanish market. The aim of this work is to review the use of syringes for intraocular administration, as well as to search for alternatives that meet the legal requirements for these unmet needs.

METHOD

A systematic review was performed following the PRISMA 2020 Guidelines by searching PubMed with the descriptors: "silicone" AND "syringes" AND ("intraocular" OR "intravitreal") and filtering all existing publications from January 2006 to December 2023, including all those articles dealing with silicone oil release in intravitreal injections and analysing the possible consequences.

RESULTS

Sixty-eight results were found, 23 of which were excluded because they did not deal with the subject under study, leaving a total of 45 articles for the systematic review. These were classified according to the conclusions obtained in 4 groups: the adverse reactions produced by silicone, the administration technique, the physicochemical aspects of silicone release, and the characteristics of the medical device. After reviewing the current manufacturers and technical data sheets of commercialized syringes, the existing syringes for this use have been collected, finding two that will probably be commercialized in Spain at the beginning of 2024: Zero Residual™ 0.2 ml SiO-free and VitreJect® Ophthalmic.

CONCLUSIONS

From the results obtained, it can be interpreted that the use of syringes and needles with silicone for intravitreal use is a concern for health professionals due to the implications and consequences that may arise in patients, the most important being adverse reactions, so it is necessary to have silicone-free syringes on the market that are specific for intraocular use. Safety and legality in the use of intraocular syringes and needles is essential to guarantee ocular integrity and patient health.

Application of Formulation Principles to Stability Issues Encountered During Processing, Manufacturing, and Storage of Drug Substance and Drug Product Protein Therapeutics

The field of formulation and stabilization of protein therapeutics has become rather extensive. However, most of the focus has been on stabilization of the final drug product. Yet, proteins experience stress and degradation through the manufacturing process, starting with fermentaition. This review describes how formulation principles can be applied to stabilize biopharmaceutical proteins during bioprocessing and manufacturing, considering each unit operation involved in prepration of the drug substance. In addition, the impact of the container on stabilty is discussed as well.

A Silicone Oil-Free Syringe Tailored for Intravitreal Injection of Biologics

Intravitreal injections (IVI) of biologics targeting vascular endothelial growth factor (anti-VEGF) led to a paradigm shift in the management and prognosis of prevalent retinal conditions. Yet, IVI are typically performed with syringes that are neither developed nor approved for this purpose. Notably, syringes lubricated with silicone oil (SiO) are extensively used despite multiple reports showing that such syringes can cause deposition of SiO droplets in the vitreous body and patient discomfort. Thus, there is a need for SiO-free substitutes specifically tailored for IVI. Here, we report on the development and testing of such a syringe. This syringe has no dead volume, and its design allows for high-accuracy dosing. Also, it permits pharmaceutical compounding and storage of bevacizumab, ranibizumab, and aflibercept for up to 30 days without compromising their functional binding or transport properties. Finally, the new syringe demonstrated a favorable safety profile regarding release of SiO compared to SiO lubricated alternatives, including commercially prefilled syringes. Accordingly, the newly developed syringe is an appealing alternative for IVI.

Silicone oil-free syringes, siliconized syringes and needles: quantitative assessment of silicone oil release with drugs used for intravitreal injection

PURPOSE

This study aimed to quantify the amount of silicone oil (SO) released across a variety of syringe and needle models routinely used for intravitreal injection.

METHODS

The release of SO was assessed in eight models of syringes, two of which were reported to be 'SO-free', and eleven models of needles with unknown SO content. To evaluate SO release within the context of anti-VEGF therapeutics, syringes were evaluated using aflibercept, bevacizumab, buffer, ziv-aflibercept and formulation buffer. All syringe tests were performed with or without agitation by flicking for syringes. Needles were evaluated without agitation only. Samples were fluorescently labelled to identify SO, and triplicate measurements were collected using imaging flow cytometry.

RESULTS

Seven out of 8 syringe models showed a statistically significant increase in the SO particle count after agitation. The two SO-free syringe models (HSW Norm-Ject, Daikyo Crystal Zenith) released the least SO particles, with or without agitation, whereas the BD Ultra-Fine and Saldanha-Rodrigues syringes released the most. More SO was released when the syringes were prefilled with formulation buffer than with ziv-aflibercept. Syringes filled with aflibercept and bevacizumab had intermediate levels. Agitation increased the release of SO into each of the drug solutions. Silicone oil (SO) was detected in all needles.

CONCLUSIONS

Agitation of the syringe by flicking leads to a substantial increase in the number of SO particles. Silicone oil (SO)-free syringes had the best performance, but physicians must also be aware that needles are siliconized and also contribute to the injection of SO into the vitreous.

Silicone microbubbles after anti-vascular endothelial growth factor injections in patients with wet age-related macular degeneration: incidence, quantification and secondary optical coherence tomography artfacts

PURPOSE

To report the incidence and quantity of silicone oil microbubbles and the relationship with the number of intravitreal anti-vascular endothelial growth factor (VEGF) injections and evaluate if microbubbles induce artefacts on optical coherence tomography (OCT) images.

METHODS

Observational, descriptive, cross-sectional study. Patients with wet age-related macular degeneration were included who had been treated for 1 year minimally with anti-VEGF injections repackaged in the hospital pharmacy. Detection and quantification of silicone microbubbles by mydriatic biomicroscopic examination were conducted 1 month after the last injection. The numbers of microbubbles were quantified on a scale of 0-3: 0, none; 1 scarce (1-10 microbubbles); 2 moderate (10-30); or 3 numerous (>30). Shadowing on OCT images was classified as 0-3: 0, none; 1 obscuring some retinal layers; 2 obscuring all retinal layers; or 3 obscuring the retinal thickness.

RESULTS

The study included 142 eyes of 98 patients (mean age, 82.4 years + 7.3; range, 65-97) treated with 2377 injections. Microbubbles were detected in 127 (89.4%) eyes, 62 (43.6%) with numerous microbubbles and 36 (25.4%) and 29 (20.4%), respectively, with scarce and moderate numbers. A positive correlation was found between the numbers of injections and intravitreal silicone (rho, 0.7). Optical coherence tomography (OCT) artefacts were detected in 11 eyes; the artefacts obscured all retinal layers in three eyes. No significant relationship could be established between the appearance of floaters and the microbubbles.

CONCLUSION

The presence and number of silicone microbubbles were correlated with the number of intravitreal injections. Microbubbles can produce OCT artefacts, which can hinder the treatment decision.

Mechanisms of sterile inflammation after intravitreal injection of antiangiogenic drugs: a narrative review

BACKGROUND

Intraocular inflammation is an uncommon but potentially vision-threatening adverse event related to anti-VEGF therapy. This is of increasing importance given both the volume of injections performed, as well as the increased prevalence of inflammation seen with newer anti-VEGF agents. Brolucizumab, the newest anti-VEGF agent, has been associated with an inflammatory retinal vasculitis and the underlying mechanism is unclear. Reviewing potential mechanisms and clinical differences of intraocular inflammation may assist clinicians and scientists in reducing the risk of these events in the future.

OBSERVATIONS

Two types of inflammation are seen with intravitreal injections, acute onset sterile inflammation and delayed onset inflammatory vasculitis. Acute onset inflammation can be subcategorized into subclinical anterior chamber inflammation and sterile uveitis/endophthalmitis. Subclinical anterior chamber inflammation can occur at rates as high as 19% after intravitreal anti-VEGF injection. Rates of sterile uveitis/endophthalmitis range from 0.05% to 4.4% depending on the anti-VEGF agent. Inflammatory vasculitis is only associated with brolucizumab and occurred in 3.3% of injections according to the post hoc review of the HAWK/HARRIER data. In addition, silicone oil from syringes can induce immunogenic protein aggregates. Agitation of the syringe, freeze thawing, shipping and improper storage prior to injection may increase the amount of silicone oil released from the syringe.

CONCLUSION

The main factors which play a role in intraocular inflammation after anti-VEGF injection can be divided into three causes: patient-specific, medication-specific and delivery-specific. The majority of clinically significant inflammation seen after intravitreal injection is an acute onset inflammatory response with most patients recovering baseline VA in 3-5 weeks. The presence of pain, hypopyon, severe anterior chamber reaction, hyperemia and significant vision loss may help distinguish infectious from non-infectious etiologies of post injection inflammation. Avoiding temperature fluctuation, mechanical shock, agitation during transport and handling of syringes/drugs, and the use of SO-free syringes may help minimize intraocular inflammation. While a definitive mechanism has not yet been established, current knowledge of the clinical presentation and vitreous histopathology of brolucizumab-retinal vasculitis favors an auto-immune type IV hypersensitivity reaction.