From: Modeling of Corneal and Retinal Pharmacokinetics after Periocular Drug Administration Invest. Ophthalmol. Vis. Sci.. 2008;49(1):320-332. doi:10.1167/iovs.07-0593 Figure Legend: Model-predicted and observed concentrations of celecoxib in the retina after administration of 3 mg celecoxib by periocular injection to BN rats using the recirculation models. (A) Four-compartment model with dissolution/release step for the formulation and inclusion of a circulation compartment. (B) Five-compartment model with dissolution/release step for the formulation, a distribution compartment for the retina, and inclusion of a circulation compartment. (C) Six-compartment model with dissolution/release step for the formulation, a distribution compartment for the retina and inclusion of a circulation compartment and a transfer compartment representing the sclera-choroid-RPE. (D) Six-compartment model with dissolution/release step for the formulation, a distribution compartment for the retina and inclusion of a circulation compartment and a transfer compartment representing the sclera-choroid-RPE with no elimination from the retina. (A, B) K10, transfer constant for transfer of drug from the periocular site to the circulation; K01, transfer constant for transfer of the drug from the circulation to the periocular site; K12, absorption rate constant for retina; K20, rate constant for transfer of the drug from the retina to the circulation compartment; K02, rate constant for transfer of the drug from the circulation compartment to the retina; K23, rate constant for transfer of the drug from the retina to the distribution compartment; K32, rate constant for transfer of drug from the distribution compartment to the retina; Kel, elimination rate constant from the circulation; Krel, rate constant for dissolution/release from the formulation. (C, D) K10, transfer constant for transfer of drug from the periocular site to the circulation; K01, transfer constant for transfer of the drug from the circulation to the periocular site; K12, absorption rate constant for sclera-choroid-RPE; K20, rate constant for transfer of the drug from the sclera-choroid-RPE to the circulation compartment; K02, rate constant for transfer of the drug from the circulation compartment to the sclera-choroid-RPE; K23, rate constant for absorption of drug into the retina from the sclera-choroid-RPE; K32, rate constant for transfer of drug from the retina to the sclera-choroid-RPE; K30, rate constant for transfer of drug from the retina to the circulation compartment; K03, rate constant for the transfer of drug from the circulation compartment to the retina; K34, rate constant for transfer of drug from the retina to the distribution compartment; K43, rate constant for transfer of rug from the distribution compartment to the retina; Kel, elimination rate constant from the circulation; Krel, rate constant for dissolution/release from the formulation. The observed data are expressed as the mean ± SD for n = 4. Date of download: 11/14/2017 The Association for Research in Vision and Ophthalmology Copyright © 2017. All rights reserved.