Abstract
Purpose:
A typical intravitreal injection dose of triamcinolone acetonide injectable suspension (Triesence, Alcon, Ft. Worth, Texas), an FDA approved preservative-free suspension, is 4.0 mg based on a 0.1 mL injection from a concentration of 40 mg/mL. A prior study has shown an increased duration of effect with increased concentration of injectant, and there is a theoretical decrease in complications with decreased volume of injectant. We describe an experimental drug preparation method for improved centrifuge concentration of triamcinolone.
Methods:
Four separate trials were conducted, in which 1.0 mL of triamcinolone acetonide injectable suspension (Triesence) was drawn from well-agitated vials into 1.0 mL syringes. The plunger was cut at the point where it protrudes from the syringe at the flanges, the needle was replaced with a sterile cap, and the syringes were placed into a balanced Quest Diagnostics Mini E 642E centrifuge with flanges down for either one or two minutes at 3380 RPM. This centrifuge allows for complete horizontal positioning of the tubes during centrifugation. After removal of syringes, separation of supernatant from medication pellet was noted and volume of each sample was measured. Using a 30-gauge needle, the supernatant was then ejected, followed by the concentrated drug pellet.
Results:
After two minutes of centrifugation, a constant volume of approximately 0.12 mL of medication pellet was achieved with 1.0 mL of triamcinolone, which equated to 40 mg of triamcinolone. This method of centrifugation resulted in a horizontal precipitate/ supernatant interface. This allowed for easy ejection of supernatant liquid while minimizing disruption of the drug pellet, which could then be separately ejected from the syringe.
Conclusions:
For physicians trying to concentrate triamcinolone from a 40 mg/mL preparation, centrifugation of triamcinolone using our methods for intravitreal use may be an effective technique for administering the drug in higher concentrations. Our method resulted in an improved technique from a prior study, in that the precipitate/supernatant interface was horizontal, which allows for estimation of injected drug dose and easier removal of the supernatant liquid.