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GAUTAM SHETTY; Key considerations for choice of syringes for delivery of intravitreal therapies in enhancing safety and efficacy of therapies injected in the eye. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1081.
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Inaccuracy of dose injected into the vitreous can result in overdosing (potentially causing increased intraocular pressure) or underdosing (potentially reducing drug efficacy and/or increasing drug injection frequency); this introduces unpredictability and potential variability in clinical outcomes for treatments delivered to treat back-of-eye disorders. Inaccuracy of dose in inherent in syringes used currently in the delivery of injectable drugs into the vitreous of the eye for the treatment of retinal disorders. The opportunity to improve clinical outcomes by reducing the dose volume from the current 50uL dose volume administered in case of anti-VEGF treatments would further exacerbate the inaccuracy problem. Also, syringes used to deliver off-label bevacizumab are not designed to store the same for an extended period of time. There are currently no guidelines from PQRI on the extractable content for drugs to be injected inside the eye. In absence of any guidelines, understanding the extractable content of syringes is a critical consideration in the safety of off-label bevacizumab in the treatment of retinal disorders.
Key determinants of inaccuracy for delivery of microliter size dose were identified in tuberculin syringes, that are currently used to deliver intravitreal drugs. A device has been developed to mitigate factors causing inaccuracy of a microliter sized dose. Dose accuracy was assessed using gravimetric technique. Extractable compounds in tuberculin and insulin syringes using water and isopropanol as extraction media was determined by HPLC/PDA/MS analysis.
Dose accuracy of 10uL dose within 2% was shown with coefficient of variation of 3%. Extractable compounds (volatile and non-volatile) were determined.
It is possible to improve accuracy of dose injected into the eye. With tools available, dose volumes injected in the eye can be reduced further to further mitigate potential risk of increase in intraocular pressure. Further research to determine toxicity of extractable compounds from syringes used to store off-label becaizumab are necessary to fully understand any potential risk posed by the same.
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