Optimisation of Syringe Performance for Ocular Injections & Beyond: Impact of Silicone Oil

In recent years, ophthalmic drug delivery has been recognised as having some of the most significantly unmet packaging and delivery needs of any injectable drug market segment. Ocular injections often require very small, precise dose volumes to be administered in a smooth, controlled manner to a precise location in the eye without the introduction of air bubbles or foreign particulate matter such as silicone oil. The vast majority of these injections are still aseptically prepared from vials into siliconised disposable syringes via a multistep process that can introduce dose inaccuracy, sterility risks, and silicone oil droplets. While these challenges can potentially be addressed by the use of appropriately designed prefilled syringes, such syringes for ocular injections are only newly emerging. Of particular concern in ocular injections is the presence of silicone oil droplets and numerous studies have confirmed that silicone oil from disposable syringes is indeed introduced into the eye during injection.1-3 In one study, affected patients were monitored for reactions or complaints of floaters in their fields of vision and while no adverse clinical events were noted, there is general consensus that the situation should be avoided.4 Kocabora et al state, “The functional and clinical consequences of intravitreal silicone oil droplets are unknown, but their occurrence could be avoided by using new-generation prefilled syringes that do not have an internal silicone coating.” 4 Furthermore, studies have shown that low-molecular-weight components of silicone oil can cause acute ocular toxicity in animal models.5 As prefilled syringes begin to gain traction as the preferred delivery mode for ocular injections, silicone oil will be a concern, not only due to the potential for direct complications related to injected droplets, but also from the perspective of safety and efficacy of the drug during long-term storage in contact with siliconised syringe components.1 The high packaging demands of the ophthalmic injectables market are reinforced by the fact that the top two drugs, Lucentis (ranibizumab) and Eylea (aflibercept), which together represented In this piece, Susan M Dounce, Senior Manager, Business Development & Innovation, Injection Systems, Datwyler Pharma Packaging; and Anil Kumar Busimi, Head of Global Product Management Syringe Business, SCHOTT Pharmaceutical Systems, describe the increasingly significant role of prefilled syringes in the delivery of ocular therapeutics, including in particular biologics, and show how the combination of silicone-free coated plungers with baked-on silicone syringe barrels minimise silicone-oil-based subvisible particles and enable the highly consistent delivery forces required in ophthalmic applications.. OPTIMISATION OF SYRINGE PERFORMANCE FOR OCULAR INJECTIONS & BEYOND: IMPACT OF SILICONE OIL