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J.W. Tsong, T. Persaud, S. Mansour; Sedimentation as Practical Method to Increase Triamcinolone Concentration for Intravitreal Injection . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4469.
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To investigate a clinically–applicable method of using passive sedimentation to increase triamcinolone concentration for intravitreal injection.
Unbreached 5.0 ml vials of triamcinolone acetonide 40 mg/ml (Kenalog® 40; Bristol–Myers Squibb) were vortexed for 2 min. The triamcinolone was drawn into sterile 1 ml TB syringes using 21 gauge 1" needles. The needles were changed to 30 gauge ½" and the volumes decreased to either 0.2 or 0.3 ml. The syringes were placed in an upright position with the needle pointing up. At designated time intervals (from 0 to 120 min), the supernatant was removed from each syringe (with the syringe still in an upright position) until the remaining volume was 0.1 ml. For analysis, this 0.1 ml was dispensed into a volumetric flask and mixed with dioxane to dissolve the triamcinolone (for a total volume of 10 ml). A sample was then centrifuged to remove precipitate. The supernatant was analyzed by HPLC using appropriate reference standards.
For both 0.2 ml and 0.3 ml initial volumes, there was a general relationship of increasing triamcinolone mass with longer sedimentation time. For the 0.2 ml initial volume, the mass at 120 min was 7.4 mg ± 0.8 mg (mean ± SE). For the 0.3 ml starting volume, the mean mass at 120 min was 9.8 mg ± 0.2 mg. For all time points collectively, there was a statistically significant difference between the two groups of 0.2 ml and 0.3 ml initial volume (p=0.0433). When comparing the two groups at the same time point, there was a statistically significant difference in average mass of triamcinolone at 20 min (p=0.0247), 25 min (p=0.002), 30 min (p=0.0333), 45 min (p=0.014), 60 min (p=0.0012), and 120 min (p=0.0488).
We have developed a simple protocol to use passive sedimentation to increase the mass (in 0.1 ml) of commercially–available Kenalog®, up to a maximum dose of 9.8 mg ± 0.2 mg. We have described the relationship of triamcinolone mass and sedimentation time for two different initial volumes. At comparable time points, using a 0.3 ml initial volume, rather than 0.2 ml, resulted in greater mass of triamcinolone. Our study demonstrates a practical and quantifiable method to increase triamcinolone concentration for intravitreal injections.
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