Further Characterization of Ocular Safety Profile of Commercially Available Preserved and Preservative-free Triamcinolone Acetonide

Purpose: To characterize the safety profile of triamcinolone acetonide (TA) for intraocular application.

Methods: In vitro cell viability assay was performed on 2 types of human ocular cells to evaluate the cytotoxicity of the simulated different vitreal concentrations (from a 1:15 dilution as if injected into 1.5 mL of rabbit vitreous to 1:50 dilution as if injected into 5 mL of human vitreous) of preservative and excipient (supernatant) from Kenalog-40. In vivo 35 guinea pigs were used for evaluating either a dose of intravitreal triamcinolone acetonide (Kenalog-40 and Triesence) or the supernatant of Kenalog-40. The animal eyes were monitored by biomicroscopy, ophthalmoscopy, tonometry, electroretinography, and histology.

Results: A ≥ 1:15 dilution of triamcinolone acetonide supernatant from Kenalog-40 did not show cytotoxicity on cultured human pigment epithelial (retinal pigment epithelium) cells or Müller cells. In vivo, neither intravitreal 6 μL (0.248 mg, equivalent to 4 mg in 0.1 mL for human eyes) nor 18 μL (0.744 mg, equivalent to 4 mg in 0.1 mL for rabbit eyes and equivalent to 12 mg in 0.1 mL for human eyes) of triamcinolone acetonide suspension showed ocular toxicity. No significant difference was noted between Kenalog-40 and Triesence clinically and histopathologically.

Conclusion: The equivalent triamcinolone acetonide doses to 0.1 mL (4 or 12 mg) intravitreal injection for human eye were found safe in guinea pig eyes. No significant difference was noted for 0.1 mL intravitreal injection between Kenalog-40 and Triesence.