Accuracy of intravitreal injection volume for aflibercept pre-filled syringe and BD Luer-Lok one-milliliter syringe

Clinical Outcomes and Experiences with Prefilled Syringes Versus Vials for Intravitreal Administration of Anti-VEGF Treatments: A Systematic Review

INTRODUCTION

Anti-vascular endothelial growth factor (VEGF) agents have been the standard treatment for retinal diseases for almost two decades. These treatments are administered via intravitreal injection using single-use vials or prefilled syringes (PFS). In this systematic review, we evaluate health care resource use and clinical outcomes and experiences with PFS for intravitreal injection of anti-VEGF treatments.

METHODS

MEDLINE, EMBASE, and The Cochrane Library were searched from January 1, 2015 to February 8, 2024 to identify literature reporting outcomes regarding procedural efficiency, health care resource use, patient and clinician experiences, and safety for currently approved anti-VEGFs (ranibizumab, aflibercept, brolucizumab) administered using PFS. Comparators were vial-based injections of the same anti-VEGFs.

RESULTS

A total of 36 publications met the criteria for inclusion in the systematic literature review; the majority were non-randomized studies, with a small number of reviews, case series, survey studies, and opinion articles. Publications reported that preparation times were significantly shorter for PFS (40.3-57.9 s) versus vials (ranibizumab, 62.8-98.0 s; aflibercept, 71.9-79.5 s), with no differences in product stability between PFS and vials. Clinicians expressed a preference for PFS and thought PFS were faster, easier to use, and had increased safety versus vials. Publications consistently reported significantly lower rates of endophthalmitis per injection with PFS versus vials (ranibizumab PFS, 0-0.02%; aflibercept PFS, 0.01-0.02%; ranibizumab vial, 0.02-0.05%; aflibercept vial, 0.02-0.06%). Four publications reported increased rates of transient vision loss after aflibercept PFS injection versus vial-based injection. No publications reported outcomes regarding health care resource use or patient experiences.

CONCLUSION

The available literature supports the increased procedural efficiency of PFS versus vial-based intravitreal injection of anti-VEGFs. PFS are positively perceived by clinicians and have a safety benefit in the form of a decreased risk of endophthalmitis versus vials.

Development of uniform fenofibrate-loaded biodegradable microparticle by membrane emulsification

Fenofibrate has shown therapeutic effects on diabetic retinopathy. However, fenofibrate can be rapidly cleared from the eye after a single intravitreal injection. Here, we aim to develop fenofibrate loaded PLGA microparticles (Feno-MP) with high drug loading and sustained in vitro release up to 6 months suitable for intravitreal injection. First, orthogonal array experimental design was applied for formulation optimization. The selected formulation parameters were used to formulate Feno-MP using homogenization method and direct membrane emulsification method. Both methods generated Feno-MP with high drug loading and sustained in vitro drug release more than 140 days. Unlike the polydisperse Feno-MP prepared using homogenization method, membrane emulsification method generated Feno-MP with uniform size distribution. By controlling the membrane pore size, 1.5 µm, 8 µm and 16 µm Feno-MP were formulated and we found that larger Feno-MP demonstrated higher drug loading, more sustained drug release in vitro with less burst drug release than the smaller Feno-MP. In conclusion, we developed Feno-MP with high drug loading and sustained release profile, and elucidated that changing the particle size could have notable impacts on drug loading and release kinetics. Formulating Feno-MP with uniform size distribution by membrane emulsification method would benefit the batch-to-batch repeatability.

Effect of Prefilled vs Vial-Drawn Syringes on Sustained Increases in Intraocular Pressure in Patients Treated With Aflibercept

Purpose: To evaluate the effect of syringe type on developing sustained intraocular pressure (IOP) increases. Methods: This retrospective cohort study included patients in a single academic center receiving antivascular endothelial growth factor (anti-VEGF) injections from 2012 to 2022 for various indications. Patients were grouped by anti-VEGF treatment of either vial-drawn or prefilled syringe delivery. Trends in IOP were recorded for 1 year after treatment began. Development of sustained IOP increase, ocular hypertension, and glaucoma was recorded. Sustained IOP increase was defined as ≥5 mm Hg above baseline for at least 4 weeks. Results: Of 257 total patients, 6 (2.3%) developed sustained IOP increases throughout the study's duration. No significant differences were noted with respect to prefilled versus vial-drawn syringe status on the development of sustained IOP increases or incident glaucoma (IOP: 1.8% vs 2.7%, respectively, P = .65; glaucoma: 0.0% vs 2.0%, respectively, P = .14). Patients treated with prefilled syringes were significantly less likely to develop ocular hypertension (2.8% vs 8.8%, P < .05). Conclusions: This study found that aflibercept intravitreal injection with prefilled syringes was not associated with a significant increase in IOP-related adverse effects when compared with those treated with vial-drawn syringes.

Risk of transient vision loss after intravitreal aflibercept using vial-prepared vs. the novel prefilled syringe formulation

Purpose

To compare the risk of transient vision loss (TVL) probably attributable to a severe intraocular pressure spike after intravitreal aflibercept application using the novel prefilled syringe (PFS) vs. the established vial system (VS).

Methods

Datasets of the intravitreal injection service of the Ludwig Maximilians-University Munich and the Technical University Munich, Germany, were screened for documentation of TVL after intravitreal injection of aflibercept. The observation period included two full months prior to the introduction of the novel PFS and two months afterwards. TVL was defined as loss of perception of hand motion for a duration of >30 s.

Results

Over a period of four months, 1720 intravitreal injections of aflibercept were administered in 672 patients. There were 842 injections with the old VS, and 878 injections using the novel PFS. Using the VS, TVL was noted during two injections (0.24%) in two patients, as compared to 11 cases of TVL (1.25%) in 10 patients with the PFS (p = 0.015). Using the PFS, patients had a 5.3-fold risk of TVL as compared to the VS (OR: 5.33; 95% CI: 1.2-24.1; p = 0.0298).

Conclusion

There was a more than five-fold risk of TVL using the novel pre-filled aflibercept syringe as compared to the established vial system. During informed consent, this risk should be discussed.

Accuracy, Precision, and Residual Volume of Commonly Used Syringes for Intravitreal Injections and the Impact on Intraocular Pressure

PURPOSE

To compare accuracy, precision, and residual volume of commonly used syringes for intravitreal injections (IVIs) and to assess the intraocular pressure (IOP) rise by variations in volumes delivered.

DESIGN

Experimental laboratory study.

SUBJECTS

No subjects were involved in this study.

METHODS

We tested 8 syringe models with 2 different needle setups, with 2 different solutions (distilled water or glycerin) and target volumes (50 and 70 μL). To obtain the delivered and residual volumes, we weighed the syringe-needle setups with scale before liquid withdrawal, with liquid, and after liquid release. We also created an experimental eye model to determine the transient rise in IOP following stepwise 10-μL increases in injection volumes.

MAIN OUTCOME MEASURES

Delivered and residual volumes, IOP rise.

RESULTS

We tested a total of 600 syringe-needle setups. Becton Dickinson (BD) Ultra-Fine (0.34 ± 0.28 μL), Zero Residual (1.53 ± 1.15 μL), and Zero Residual Silicone Oil-free (1.40 ± 1.16 μL) syringes showed the lowest residual volume (P < 0.001) in comparison with the others (range: 24.86 ± 1.78 μL for Injekt-F to 51.97 ± 3.37 μL for Omnifix-F). The most accurate setups were (percentage deviation from target volume): Zero Residual Silicone Oil-free (+ 0.70%), Zero Residual 0.3 ml (+ 4.49%), BD Ultra-Fine (+ 7.83%), Injekt-F (9.42%), Norm-Ject (+ 15.88%), Omnifix-F (+ 16.96%), BD Plastipak Brazil (+17.96%), and BD Plastipak Spain syringes (+ 19.41%). There was a statistically significant difference between the Zero Residual Silicone Oil-free syringe and all other syringes (P < 0.0001), except for the Zero Residual 0.3-ml syringe (P = 0.029). The coefficient of variation was low for all syringes. The modeled IOP rise ranged from 32.3 (standard deviation [SD], 1.4) mmHg for 20-μL injection volume to 76.5 (SD, 1.0) mmHg for 80-μL injection volume. For the standard 50-μL injection volume, the peak pressure was 50.7 (SD, 0.1) mmHg, and the pressure rise duration was 28 (SD, 2) minutes.

CONCLUSIONS

There were significant differences in accuracy and residual volume between syringes, whereas they showed a high precision. Volume excess results in a considerable increase in IOP rise after injection. These findings may provide a relevant overview to clinicians and to both device and drug manufacturers regarding pharmacoeconomic, safety, and efficacy issues.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

SYRINGE DESIGN AND FILLING TECHNIQUE AFFECT ACCURACY OF ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR INTRAVITREAL INJECTIONS

PURPOSE

To evaluate the effect of syringe design and filling technique on the accuracy of anti-vascular endothelial growth factor delivery.

METHODS

Volume output was measured with three syringe designs: a 1.0-mL slip-tip syringe, a 1.0-mL Luer-lock syringe, and a ranibizumab prefilled syringe-using two filling techniques ("upward" and "downward") and two fluids (water and bevacizumab). A total of 300 simulated injections were performed. Accuracy was determined by difference from the intended volume of 50 µ L and by mean absolute percentage error.

RESULTS

Volume outputs were significantly different between syringe designs, with mean values of 61.99 ± 4.18 µ L with the 1-mL slip-tip syringe, 57.43 ± 4.95 µ L with the Luer-lock 1-mL syringe, and 51.06 ± 4.74 µ L with the ranibizumab syringe, making the latter the most accurate syringe. There were 37 cases (12.3%) of underdosing below 50 µ L, the majority of which occurred with the ranibizumab syringe. The "downward" technique reduced the occurrence of air bubbles.

CONCLUSION

Intravitreal injections using 1.0-mL syringes are less accurate than using the ranibizumab prefilled syringe, which has a low-volume and low dead-space plunger design. The variability in volume output may result in less predictable treatment response, especially in cases of underdosing, which were more common with the ranibizumab syringe.

Incidence of severe rise in intraocular pressure after intravitreous injection of aflibercept with prefilled syringes

Our aim was to analyze the intraocular pressure (IOP) changes following different intravitreous injection (IVI) procedures with or without prefilled syringes (PFS) and to elaborate their possible causes. Clinical study and laboratory assessment. 173 eyes of 141 patients. The IOP was prospectively measured pre- and postoperatively in three groups of patients receiving IVI either with ranibizumab (RP), aflibercept PFS (AP) or aflibercept vials (AV). The AP emptying volume (EV) was assessed using 40 aflibercept PFS vials: the plunger was aligned precisely (normal volume, NV) or right below the indication line (high volume, HV) and the drug was ejected with (wP) or without forced pressure (nP). Primary outcome was post-treatment IOP with type of IVI and pre-treatment IOP as fixed factors. Secondary outcome was identification of possibly confounding factors (age, sex, pathology, presence of pseudophakia, spherical error, and number of injections) and IOP > 30 mmHg post-treatment. An IOP rise above 30 mmHg was observed in 8/38 (22%), 16/51 (31%) and 35/86 (41%) cases in the RP, AV and AP groups, respectively (p = 0.129). Pre-treatment IOP was the only predictive variable for IOP rise (p < 0.001). The EV values in the NVnP, NVwP, HVnP and HVwP groups were 56.06 ± 10.32, 70.69 ± 4.56, 74.22 ± 7.41 and 81.63 ± 3.67 µl, respectively (p < 0.001). We observed a marked, although not significantly higher incidence of IOP elevations with the aflibercept PFS. One possible reason may be the error-proneness of administering the correct volume with the AP. Caution should be taken when using the aflibercept PFS in order to prevent potential optic nerve damage in cases with marked elevation in IOP.

Long-acting ocular drug delivery technologies with clinical precedent

INTRODUCTION

Ocular long-acting injectables and implants (LAIIs) deliver drug at a controlled release rate over weeks to years. A reduced dose frequency eases the treatment burden on patients, minimizes the potential for treatment-related adverse effects, and improves treatment adherence and persistence.

AREAS COVERED

This review provides a comprehensive landscape of ocular LAII drug delivery technologies with clinical precedent, including eight commercial products and 27 clinical programs. Analysis of this landscape, and the specific technologies with the greatest precedent, provides instructive lessons for researchers interested in this space and insights into the direction of the field.

EXPERT OPINION

Further technological advancement is required to create biodegradable LAIIs with extended release durations and LAIIs that are compatible with a broader array of therapeutic modalities. In the future, ocular LAII innovations can be applied to diseases with limited treatment options, prophylactic treatment at earlier stages of disease, and cost-effective treatment of ocular diseases in global health settings.