Abstract
Purpose: :
To report on the decay of concentration of intravitreal applicated triamcinolone acetonide in the anterior chamber and vitreous over a 6 month period of time using a rabbit animal model
Methods: :
The study included 18 eyes of 18 white New Zealand rabbits, which received 15mg of triamcinolone acetonide into the vitreous by pars plana injection. Samples of the anterior and posterior chamber were acquired at days 1, 3, 7, 2 weeks and months 1, 2, 4 and 6. The concentration of triamcinolone was analyzed for each probe.
Results: :
Triamcinolone concentrations of the vitreous were significantly higher over the whole 6 month period of time compared to anterior chamber readings (e.g. day 1: 17600±10900µg/l vs. 22.4±19.5µg/l; day 30: 531.6±330.5 vs 5.5±2.6µg/l). Highest concentrations in the anterior chamber could be detected 3 days after injection (24.4±14.4 µg/l). Triamcinolone levels in the vitreous followed a two compartment model with an exponential drop of concentration within the first 21 days, followed by a steady decline over the following months. A similar characteristic was found in the anterior chamber, whereas the steady decay started later than 90 days. At the 6 month period, concentrations of triamcinolone were 128±80.5µg/l (viteous) and 4.5±2.3µg/l (anterior chamber).There was no significant cataract formation during the follow up time, except 3 eyes which developed traumatic cataract after iatrogenous lenstouch. No endophthalmitis was found. One eye showed a retinal detachment
Conclusions: :
Results suggest a decay of triamcinolone concentration following two different functions, first exponentially followed by a more linear decrease. There was a highly significant difference in concentration between anterior and posterior chamber, which persists even after a six month period of time, suggesting a barrier of diffusion between posterior and anterior chamber for intavitreal triamcinolone.
Keywords: corticosteroids • pharmacology • vitreous