Ocular Pharmacokinetics of Therapeutic Antibodies Given by Intravitreal Injection: Estimation of Retinal Permeabilities Using a 3-Compartment Semi-Mechanistic Model.
Mol Pharm
; 14(8): 2690-2696, 2017 08 07.
Article
em En
| MEDLINE
| ID: mdl-28631484
ABSTRACT
Intravitreally (IVT) injected macromolecules for the treatment of age-related macular degeneration must permeate through the inner limiting membrane (ILM) into the retina and through the retinal pigment epithelium (RPE) to enter the choroid. A quantitative understanding of intraocular transport mechanisms, elimination pathways, and the effect of molecular size is currently incomplete. We present a semimechanistic, 3-compartment (retina, vitreous, and aqueous) pharmacokinetic (PK) model, expressed using linear ordinary differential equations (ODEs), to describe the molecular concentrations following a single IVT injection. The model was fit to experimental rabbit data, with Fab, Fc, IgG, and IgG null antibodies and antibody fragments, to estimate key ocular pharmacokinetic parameters. The model predicts an ocular half-life, t1/2, which is the same for all compartments and dependent on the hydrodynamic radius (Rh) of the respective molecules, consistent with observations from the experimental data. Estimates of the permeabilities of the RPE and ILM are derived for Rh values ranging from 2.5 to 4.9 nm, and are found to be in good agreement with ex-vivo measurements from bovine eyes. We show that the ratio of these permeabilities largely determines the ratio of the molecular concentrations in the retina and vitreal compartments and their dependence on Rh. The model further provides estimates for the ratio of fluxes corresponding to the elimination pathways from the eye, i.e., aqueous humor to retina/choroid, which increase from 51 to 71 as Rh decreases. Our semimechanistic model provides a quantitative framework for interpreting ocular PK and the effects of molecule size on rate-determining parameters. We have shown that intraocular permeabilities can be reasonably estimated from 3-compartment ocular PK data and can determine how these parameters influence the half-life, retinal permeation, and elimination of intravitreally injected molecules from the eye.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Retina
/
Epitélio Pigmentado da Retina
/
Anticorpos
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Mol Pharm
Assunto da revista:
BIOLOGIA MOLECULAR
/
FARMACIA
/
FARMACOLOGIA
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Reino Unido