Abstract:ABSTRACT.Purpose: This study aimed to: (1) determine the relative efficiencies of topical and systemic absorption of drugs delivered by eyedrops to the anterior and posterior segments of the eye; (2) establish whether dexamethasone-cyclodextrin eyedrops deliver significant levels of drug to the retina and vitreous in the rabbit eye, and (3) compare systemic absorption following topical application to the eye versus intranasal or intravenous delivery. Methods: In order to distinguish between topical and systemi… Show more
“…18 For diseases requiring long-term drug administration such as those of the retina and vitreous body, a dexamethasone/cyclodextrin mixture applied to the ocular surface increased retinal penetration two-fold relative to systemic administration. 19 In situ gels are a novel type of ophthalmic drug delivery system with a longer retention time than that of existing approaches, and they reduce administration frequency and improve bioavailability. In vivo studies have shown that a temperature-sensitive chitosan hydrogel administered as ocular drops had high penetration and sustained release over 12 h while reducing intraocular pressure.…”
Drug delivery carriers can maintain effective therapeutic concentrations in the eye. To this end, we developed lipid nanoparticles (L/NPs) in which the surface was modified with positively charged chitosan, which engaged in hydrogen bonding with the phospholipid membrane. We evaluated in vitro corneal permeability and release characteristics, ocular irritation, and drug dynamics of modified and unmodified L/NPs in aqueous humor. The size of L/NPs was uniform and showed a narrow distribution. Corneal permeation was altered by the presence of chitosan and was dependent on particle size; the apparent permeability coefficient of dexamethasone increased by 2.7 and 1.8 times for chitosan-modified and unmodified L/NPs, respectively. In conclusion, a chitosan-modified system could be a promising method for increasing the ocular bioavailability of unmodified L/NPs by enhancing their retention time and permeation into the cornea. These findings provide a theoretical basis for the development of effective drug delivery systems in the treatment of ocular disease.
“…18 For diseases requiring long-term drug administration such as those of the retina and vitreous body, a dexamethasone/cyclodextrin mixture applied to the ocular surface increased retinal penetration two-fold relative to systemic administration. 19 In situ gels are a novel type of ophthalmic drug delivery system with a longer retention time than that of existing approaches, and they reduce administration frequency and improve bioavailability. In vivo studies have shown that a temperature-sensitive chitosan hydrogel administered as ocular drops had high penetration and sustained release over 12 h while reducing intraocular pressure.…”
Drug delivery carriers can maintain effective therapeutic concentrations in the eye. To this end, we developed lipid nanoparticles (L/NPs) in which the surface was modified with positively charged chitosan, which engaged in hydrogen bonding with the phospholipid membrane. We evaluated in vitro corneal permeability and release characteristics, ocular irritation, and drug dynamics of modified and unmodified L/NPs in aqueous humor. The size of L/NPs was uniform and showed a narrow distribution. Corneal permeation was altered by the presence of chitosan and was dependent on particle size; the apparent permeability coefficient of dexamethasone increased by 2.7 and 1.8 times for chitosan-modified and unmodified L/NPs, respectively. In conclusion, a chitosan-modified system could be a promising method for increasing the ocular bioavailability of unmodified L/NPs by enhancing their retention time and permeation into the cornea. These findings provide a theoretical basis for the development of effective drug delivery systems in the treatment of ocular disease.
“…Ocular steroids can be available in the systemic circulation and can cause systemic adverse effects. In a study, when the identical doses of steroid were administrated intravenously, intranasally and topically in the conjunctiva, the rates of systemic absorption have been found similar (7). Also, it has been previously reported that topical steroid eye drops may trigger the manifestation of HZ infection (8).…”
Section: Figure 1: the Typical Vesicular Rash Of Herpes Zoster Can Bementioning
Herpes zoster is an acute viral infection characterized by painful dermatomal vesicular eruption on an erythematous base. It results from reactivation of latent varicella zoster virus infection that has persisted in dorsal root ganglia. The disease is commonly encountered in elderly and immunocompromised patients. In the current report, we have presented a 70-year-old woman who developed herpes zoster infection on her left subpectoral-dorsal site following uncomplicated cataract surgery. The patient was consulted with dermatology clinic and treated successfully.
“…Some studies have indicated that drugs may effectively reach the retina after topical administration. 10) It is important to investigate the detailed pharmacokinetics of the posterior eye tissues with respect to the concentration distribution of drugs.…”
The purpose of this study was to analyze drug pharmacokinetics in the posterior eye tissues after topical instillation. For the in vivo study, the concentrations of ofloxacin in rabbit ocular tissues were analyzed by high performance liquid chromatography at 1, 2, and 3 h after instillation. For the in silico simulation, the concentration distribution of ofloxacin in the eye was calculated by the ocular pharmacokinetic model based on the diffusion/partition model. The simulated profiles were then compared with the in vivo experimental findings. In the in vivo study, the drug concentration in the posterior vitreous body initially decreased with time after topical instillation, and thereafter, the concentration increased. The in silico simulation of ocular pharmacokinetics indicated that the drug penetration of the posterior vitreous body was determined by three major pathways: (1) the initial transscleral penetration, (2) the intermediate transcorneal penetration, and (3) the late transretinal penetration. The in vivo findings were well described by a series of contributions by these three pathways. In conclusion, the present in vivo and in silico studies suggest that the instilled drugs initially reached the posterior vitreous body by diffusion through the sclera and then later by corneal penetration and systemic circulation.
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