title: Hydrogel Ring for Topical Drug Delivery to the Ocular Posterior Segment.
abstract: To investigate the efficacy of a topical hydrogel ring for drug delivery to the posterior segment of the rabbit eye.
  
  
  
  Novel hydrogel corneal lenses (CL), scleral/corneal lenses (S/CL), and rings were prepared using poly(hydroxyethyl methacrylate). The devices were immersed in 0.3% ofloxacin ophthalmic solution (OOS) to homogeneously distribute the drug throughout the hydrogel. The medicated CL, S/CL, Ring 1 (standard ring), or Ring 2 (shape-optimized ring) was applied to the surface of the cornea, cornea/bulbar conjunctiva, or bulbar conjunctiva of albino rabbits, respectively. Medicated rings did not touch the corneal surface. In another group, one OOS drop was administered to the eye. After 0.25-8 hours, the hydrogel devices were removed and ocular tissues were harvested. High-performance liquid chromatography (HPLC) was used to measure the ofloxacin concentration in the devices and tissues. The drug concentrations in the posterior segment tissues were compared among ofloxacin delivery methods.
  
  
  
  One hour after placement, eyes treated with Ring 1 or S/CL had markedly higher ofloxacin levels in the posterior segment tissues (conjunctiva, sclera, and retina/choroid) than eyes treated with topical OOS or a CL. Lower levels of ofloxacin were found in anterior segment tissues (cornea and aqueous humor) in eyes treated with Ring 1 compared to those treated with S/CL. Ring 2 most effectively delivered ofloxacin to the retina/choroid. The tissue ofloxacin concentration in the fellow eye was markedly lower than the eye treated with Ring 2.
  
  
  
  Our results suggest that hydrogel rings are effective in delivering topical ophthalmic drugs to the posterior segment. The drugs are most likely delivered via the transconjunctival/scleral route by lateral diffusion across the bulbar conjunctiva and through the sclera. Systemic drug delivery to the posterior segment is minimal.
authors.affiliation: a Research Laboratories, Senju Pharmaceutical Co., Ltd. , Hyogo , Japan .
authors.forename: Yuko
authors.initials: Y
authors.lastname: Shikamura
authors.affiliation: b Research and Development, SEED Co., Ltd. , Saitama , Japan and.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Yamazaki
authors.affiliation: b Research and Development, SEED Co., Ltd. , Saitama , Japan and.
authors.forename: Toru
authors.initials: T
authors.lastname: Matsunaga
authors.affiliation: b Research and Development, SEED Co., Ltd. , Saitama , Japan and.
authors.forename: Takao
authors.initials: T
authors.lastname: Sato
authors.affiliation: a Research Laboratories, Senju Pharmaceutical Co., Ltd. , Hyogo , Japan .|c Graduate School of Computer Science and Systems Engineering, Kyushu Institute of Technology , Fukuoka , Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Ohtori
authors.affiliation: c Graduate School of Computer Science and Systems Engineering, Kyushu Institute of Technology , Fukuoka , Japan.
authors.forename: Kakuji
authors.initials: K
authors.lastname: Tojo
mesh_terms: D000287:Administration, Topical; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid; D016503:Drug Delivery Systems / Q000295:instrumentation*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D023421:Models, Animal; D015242:Ofloxacin / Q000008:administration & dosage* / Q000493:pharmacokinetics; D009883:Ophthalmic Solutions / Q000008:administration & dosage; D057972:Posterior Eye Segment / Q000378:metabolism*; D011817:Rabbits
chemical_list: D000900:Anti-Bacterial Agents; D009883:Ophthalmic Solutions; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D015242:Ofloxacin
keywords: Contact lens; drug delivery; hydrogel ring; ofloxacin; retina