A comparative study between a transscleral sustained-release device and eyedrops on intraocular distribution of carteolol hydrochloride

The objectives of this study were to develop a sustained-release device for carteolol hydrochloride (CH) and investigate any potential difference in the intraocular distribution of this agent between the transscleral administration of the device and treatment with eyedrops. The device was formulated with photocurable resin, poly (ethyleneglycol) dimethacrylate, to fit within the curve of the rabbit eyeball. In vitro study showed that CH was released in a sustained-release manner for 2 weeks. The concentration of CH in the retina, choroid/retinal pigment epithelium, sclera, iris, and aqueous humor was determined by high-performance liquid chromatography. Transscleral administration was able to deliver CH to the posterior segment (i.e., retina and choroid/retinal pigment epithelium) rather than the anterior segment (i.e., aqueous humor), while eyedrops delivered CH only to the anterior segment. Transscleral administration could deliver CH to aqueous humor at half the concentration versus treatment with eyedrops and reduced intraocular pressure (IOP) at 1 day after implantation; however, the IOP-lowering effect was not sustained thereafter. In conclusion, transscleral drug delivery may be a useful method for the reduction of IOP. Notably, the aqueous concentration must be equal to that delivered by the eyedrops, and this approach might be preferable for drug delivery to the posterior segment of the eye.