[Characteristic of ocular safety profile of triamcinolone made in China]

To characterize the safety profile of triamcinolone acetonide made in China (Transton) and triamcinolone acetonide acetate (Tongyong) for their ocular application.

Experimental study. In vitro cell viability assay was performed on 3 types of human ocular cells to evaluate the cytotoxicity of the simulated 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 Transton and Tongyong using MTT method.In vivo 28 guinea pigs, randomly divided into four groups, were used for evaluating either intravitreal 6 µl of the two types of triamcinolone suspension or 18 µl of their supernatant. Following the injections, the eyes were monitored by biomicroscopy, ophthalmoscopy, tonometry, electroretinography, and histology. The Dunnett's test was used to analyze in vitro cell viability. Paired sample t-test and Generalized Estimating Equations (GEE) were respectively used to compare electroretinography data and intraocular pressure between experimental eyes and the control eyes.

The undiluted supernatant of Transton and Tongyong was toxic to human scleral fibroblasts when compared with their control groups (MTT values = 0.046 ± 0.036 and 0.044 ± 0.05 versus 0.367 ± 0.106 and 0.413 ± 0.128) (P < 0.01) or with the BSS group (0.368 ± 0.106 and 0.441 ± 0.137) (P < 0.01). 1:15 or greater dilution of supernatant of Transton and Tongyong did not show cytotoxicity on cultured human retinal pigment epithelium cells or Müller cell (P > 0.05), but 1:15 dilution of Tongyong supernatant showed cytotoxicity on the Müller cells (MTT value = 0.366 ± 0.062 versus 0.417 ± 0.042 for BSS) (P = 0.03). In vivo, neither intravitreal 6 µl (0.25 mg, equivalent to 4 mg in 0.1 ml for human eyes) of the suspension nor 18 µl (equivalent resultant preservative concentration to intravitreal 4 mg in 0.1 ml for rabbit eyes) of the supernatant of Transton and Tongyong showed ocular toxicity.

The equivalent dose (6 µl) to 4 mg in 0.1 ml intravitreal suspension for human eye or equivalent resultant preservative concentration to 0.1 ml intravitreal suspension for rabbit eye is found safe in guinea pig eyes.