Preservative-free triamcinolone acetonide injectable suspension versus "traditional" triamcinolone preparations: impact of aggregate size on retinal biocompatibility.

PURPOSE: To evaluate the biocompatibility of the three currently most commonly used triamcinolone acetonide (TA) preparations on retinal cells.

METHODS

Preservative containing KL (Kenalog-40; Bristol-Myers Squibb, Princeton, NJ), compounded preservative-free triamcinolone acetonide (PFTA; compounded from Volon A; Dermapharm, Vienna, Austria), and preservative-free triamcinolone acetonide injectable suspension (TRIESENCE; Alcon, Inc, Fort Worth, TX) (0.01-1 mg/mL) were either added directly on top or separated by a Boyden chamber filter or by a layer of vitreous to confluent cell cultures of retinal pigment epithelial cells (ARPE19) or retinal ganglion cells (RGC5). The distribution pattern of the TA crystals was assessed microscopically. Cell viability was assessed using MTT-ELISA and Live/Dead-Assay.

RESULTS

Sedimentation of triamcinolone acetonide injectable suspension, KL, or PFTA caused a pronounced decrease in cell viability. Cytotoxicity was most pronounced when triamcinolone acetonide injectable suspension and PFTA were used. Without direct sedimentation of TA crystals on top of the cells, none of the three formulations were cytotoxic. Triamcinolone acetonide injectable suspension showed the largest and most dense TA crystal aggregates on top of the cells.

CONCLUSION

Retinal cytotoxicity of TA seems only to occur when there is intimate contact of TA crystals with the cellular membrane. Cytotoxicity depends on the number and size of TA crystal aggregates-with larger conglomerates being more harmful. Of the TA formulations tested, triamcinolone acetonide injectable suspension had the strongest tendency to form large TA crystal conglomerates and to gravitate downward.