Abstract
Purpose: :
To determine the sedimentation rates of two different commercial preparations of triamcinolone acetonide (TA), Kenalog 40mg/ml (Bristol-Myers Squibb, Princeton, NJ) and Triesence 40mg/ml (Alcon, Ft. Worth, TX).
Methods: :
Though Kenalog is not approved for intraocular use, is widely used as an intravitreous injection for a variety of posterior segment disorders. Triesence is an FDA approved, preservative-free formulation of TA for intravitreous injection. Higher concentrations of TA have been found to increase the duration of effect without necessarily increasing the side effects. In addition, decanted TA, in which the supernatant is removed, has been found to decrease preservative-related side effects. Using decanted TA permits use of higher concentrations and may also afford greater safety. We conducted a study to determine the sedimentation rates of two different formulations of TA. The endpoints of the study were to estimate the time needed to achieve particular concentrations of TA and to determine if the new, approved TA formulation could be further concentrated in the same manner as Kenalog. Aliquots from single dose vials of Kenalog and Triesence were drawn into 1cc tuberculin syringes using the same method via a 25-gauge needle. All syringes were placed in a fixed upright position during the study period. The volumes of Kenalog ranged from 0.1ml to 1.0ml with gradations of 0.1ml for a total of 10 samples. We used 2 volumes of Triesence, 0.4ml and 1.0ml for a total of 2 samples. Measurement of sedimentation in each sample, separation of supernatant from medication pellet, was performed at 15 minute intervals from 0 to 240 minutes and then again at 26.5 hours. The turbidity of the supernatant was also noted at each time point.
Results: :
In the Triesence samples, no layering was noted at any of the time points; however, there was some loculation seen in segments of the syringe at 26.5 hours. Gradients were noted in each of the samples of Kenalog. A constant volume of supernatant and medication was achieved by 150 minutes for all aliquots of Kenalog.
Conclusions: :
Using the above method we were unable to further concentrate Triesence beyond 40mg/ml. For physicians trying to concentrate Kenalog from a 40mg/ml vial or those trying to use only decanted TA, a 150-minute wait time would allow for an accurate dose of medication.
Keywords: clinical (human) or epidemiologic studies: systems/equipment/techniques • injection • drug toxicity/drug effects