Quantification of sedimented triamcinolone for intravitreal injection.

Abstract

To develop a practical method to concentrate triamcinolone acetonide for intravitreal injection. A protocol using sedimentation was developed to increase the concentration of triamcinolone acetonide in a 0.1 mL dose. Two variables were investigated: sedimentation time and initial volume of triamcinolone acetonide. Predetermined volumes (0.2 mL to 1 mL) of triamcinolone acetonide were aspirated into tuberculin syringes. Each syringe was placed in a vertical position for a designated time (0 to 120 minutes). The supernatant was then discarded to reduce the volume to 0.1 mL. High-performance liquid chromatography was then used for quantification of the triamcinolone acetonide. The greatest concentrations of triamcinolone acetonide were seen after 120 minutes of sedimentation. At that time point, the 0.2 mL, 0.3 mL, and 0.5 mL initial volumes resulted in, respectively, 7.4 mg +/- 0.8 mg (mean +/- SE), 9.8 mg +/- 0.2 mg, and 16.4 mg +/- 0.7 mg triamcinolone acetonide in 0.1 mL. The 1.0-mL initial volume resulted in 25.7 mg +/- 0.9 mg triamcinolone acetonide in 0.1 mL; this was the maximum concentration achieved in the experiment. The authors have developed a simple protocol to use sedimentation to greatly increase the concentration of triamcinolone acetonide, starting from commercially available triamcinolone acetonide up to a maximum of 25.7 mg per 0.1 mL (257 +/- 9 mg/mL). This study demonstrates a practical and quantifiable method to increase triamcinolone concentration for intravitreal injections.