Abstract
Purpose: :
To describe the elimination and distribution of intraocular triamcinolone acetonide (TA) after sub–tenon injection using computer model, Virtual Ocular PK.
Methods: :
The TA concentration in the eye was described by using a pharmacokinetic model for ocular drug delivery "Virtual Ocular PK".ref The concentration distribution in the eye was calculated following the sub–tenon injection and the mean concentration in each ocular tissue was then evaluated by integrating the concentration distribution. The simulated concentration profile was then compared with the experimental profile when TA suspension was injected into sub–tenon capsule on albino rabbit in vivo.
Results: :
The simulated profile of mean concentration in the vitreous body was in good agreement with the in vivo experimental findings. The model parameters, the diffusion coefficient and the partition coefficient, were determined independently from the in vivo and in vitro experiments. The mathematical simulation described that the drug concentration near the site of injection became markedly high compared with that near the anterior site of vitreous body, and that the drug was eliminated mainly from the posterior chamber with an appreciable concentration gradient. When an appropriate boundary conditions, the concentration profiles in the eye showed a "stadium–like distribution". We found that the Virtual Ocular PK was useful to predict the local concentration in the eye following sub–tenon injection.
Conclusions: :
The simulated concentration of intraocular TA after sub–tenon injection was in good agreement with the experimental results obtained from in vivo study. The present computational approach is useful to simulate the effects of various factors for drug delivery system design of sub–tenon administration as well as for injection. Ref. K.Tojo Chem. Pharm. Bull., 52 (11), 1290–1294, 2004.