Related Experiment Video
Updated: Aug 24, 2026

Use of Rabbit Eyes in Pharmacokinetic Studies of Intraocular Drugs
Published on: July 23, 2016
Ocular pharmacokinetic/ pharmacodynamic modeling for bunazosin after instillation into rabbits
Koji Sakanaka1, Kouichi Kawazu, Masahide Tomonari
1Department of Hospital Pharmacy, Nagasaki University School of Medicine, Nagasaki 852-8501, Japan. sasaki@net.nagasaki-u.ac.jp
Purpose:
To develop a pharmacokinetic/pharmacodynamic (PK/PD) model for an alpha1-blocker (bunazosin) after instillation. The PK/PD model can predict both the drug concentrations in various ocular tissues and the hypotensive effect.
Methods:
Bunazosin concentrations were determined with High Performance Liquid Chromatography (HPLC) in tear fluid, the aqueous humor, cornea, and iris-ciliary body after instillation or ocular injection into the anterior chamber in rabbits. After instillation of bunazosin in rabbits, intraocular pressure (IOP) was also determined with a pneumatic tonometer. The PK/PD parameters were estimated by fitting the concentration-time profiles and the hypotensive effect-time profiles to the developed PK/PD models using the MULTI (RUNGE) program.
Results:
On the basis of the concentration-time profiles of bunazosin, a PK model, including seven compartments, was developed for examining the behavior of bunazosin after instillation. Then, two PK/ PD models for hypotensive effect of bunazosin were developed using an indirect response (model A) and the relationship between IOP and aqueous humor flow (model B). These models well described the concentration-time profiles and hypotensive effect-time profiles of bunazosin after instillation.
Conclusions:
This study is the first trial to develop a PK/PD model for an antiglaucoma agent using an indirect response and the relationship between IOP and aqueous humor flow.
Related Concept Videos
One-Compartment Open Model for IV Bolus Administration: General Considerations
The drug's presence in the body is defined by an equation representing the difference between the rates of drug entry and exit. Key parameters—elimination rate constant, half-life,...
Ophthalmic Drug Delivery Systems
Two-Compartment Open Model: IV Bolus Administration
The disparity between drug input and the sum of drug transfer rates between...
One-Compartment Open Model for IV Bolus Administration: Estimation of Elimination Rate Constant, Half-Life and Volume of Distribution
Impact of Pharmacokinetic–Pharmacodynamic Models: Regulatory Decisions
Compartment Models: Two-Compartment Model

