Urea and the vitreous barrier of the eye

Bleeker, G. M.; Haeringen, N.J. van; Glasius, E.

doi:10.1016/s0014-4835(68)80023-5

Cited by 18 publications

(6 citation statements)

References 2 publications

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“…Carrier-independent penetration of antibiotics and other drugs into the eye (10,13,19,44,53,61), like that at other anatomical sites (3,13,19,30,44,46,53,61), correlates with physicochemical properties, including lipophilicity and MW as well as protein binding. These independent variables were considered in the multiple-linear-regression model.…”

Section: Discussionmentioning

confidence: 99%

Pharmacokinetics of Sparfloxacin in the Serum and Vitreous Humor of Rabbits: Physicochemical Properties That Regulate Penetration of Quinolone Antimicrobials

Liu

Perkins

et al. 1998

Antimicrob Agents Chemother

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We have used a recently described animal model to characterize the ocular pharmacokinetics of sparfloxacin in vitreous humor of uninfected albino rabbits following systemic administration and direct intraocular injection. The relationships of lipophilicity, protein binding, and molecular weight to the penetration and elimination of sparfloxacin were compared to those of ciprofloxacin, fleroxacin, and ofloxacin. To determine whether elimination was active, elimination rates following direct injection with and without probenecid or heat-killed bacteria were compared. Sparfloxacin concentrations were measured in the serum and vitreous humor by a biological assay. Protein binding and lipophilicity were determined, respectively, by ultrafiltration and oil-water partitioning. Pharmacokinetic parameters were characterized with RSTRIP, an iterative, nonlinear, weighted, least-squares-regression program. The relationship between each independent variable and mean quinolone concentration or elimination rate in the vitreous humor was determined by multiple linear regression. The mean concentration of sparfloxacin in the vitreous humor was 59.4% ± 12.2% of that in serum. Penetration of sparfloxacin, ciprofloxacin, fleroxacin, and ofloxacin into, and elimination from, the vitreous humor correlated with lipophilicity (r 2 > 0.999). The linear-regression equation describing this relationship was not improved by including the inverse of the square root of the molecular weight and/or the degree of protein binding. Elimination rates for each quinolone were decreased by the intraocular administration of probenecid. Heat-killedStaphylococcus epidermidis decreased the rate of elimination of fleroxacin. Penetration of sparfloxacin into the noninflamed vitreous humor was greater than that of any quinolone previously examined. There was an excellent correlation between lipophilicity and vitreous entry or elimination for sparfloxacin as well as ciprofloxacin, fleroxacin, and ofloxacin. There are two modes of quinolone translocation into and out of the vitreous humor: diffusion into the eye and both diffusion and carrier-mediated elimination out of the vitreous humor.

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Section: Discussionmentioning

confidence: 99%

Pharmacokinetics of Sparfloxacin in the Serum and Vitreous Humor of Rabbits: Physicochemical Properties That Regulate Penetration of Quinolone Antimicrobials

Liu

Perkins

et al. 1998

Antimicrob Agents Chemother

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“…Measurements of the penetration of tracers into the vitreous are difficult to analyze in terms of the retinal barrier, because the greater part of the total penetration comes from the posterior aqueous humor. However, regional analysis of the vitreous body in the eyes of both cats (DAVSON et al 1949) and rabbits (KINSEY 1960;BLEEKER et al 1968 a) which were enucleated and frozen soon after small tracers had been injected into the blood shows a significant penetration near the posterior retina after 30 min or less, long before the tracer could have diffused there from the ciliary body. The level in the posterior part of the vitreous, about 5% of that in the blood after 30 min, leads to a retinal surface permeability of about 2 x 10-2 cm h -1.…”

Section: The Blood-vitreous Barriermentioning

confidence: 99%

Ocular Pharmacokinetics

Maurice¹,

Mishima²

1984

Handbook of Experimental Pharmacology

222

169

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“…Urea readily diffuses across the ocular surface and would gain entrance into the eye (Bleeker et al 1968), potentially increasing the osmolarity of the internal eye fluids as compared to circulating blood. This may set up an osmolarity gradient which would attract fluid into the eye and raise intraocular pressure.…”

Section: Discussionmentioning

confidence: 99%

“…Because of its ready absorption into the eye, urea itself might not be the ideal agent (Bleeker et al 1968). Rather, a urea derivative that decreases ocular penetration yet retains surface activity is likely to be the best agent.…”

Section: Discussionmentioning

confidence: 99%

Topical urea as a treatment for non‐infectious keratopathy

Charlton

Schwab

Stuchell

1996

Acta Ophthalmologica Scandinavica

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The purpose of this study was to evaluate topical urea ophthalmic ointment as an agent to promote epithelial healing. Corneal epitheliopathy and epithelial defects were chemically induced in rabbits. Urea ophthalmic ointment was administered to one eye and control ointment to the fellow eye. The rabbits were examined by a masked observer for eleven days and points were awarded for steps of improvement in their ocular surface disease. The eyes receiving the urea ointment improved an average of 5.73 points while the control eyes improved 4.2 points (p < 0.0001). In conclusion, topical urea dissolved in a bland ointment encourages corneal reepithelialization and limits epithelial damage after toxic injury to corneal epithelium.

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Urea and the vitreous barrier of the eye

Cited by 18 publications

References 2 publications

Pharmacokinetics of Sparfloxacin in the Serum and Vitreous Humor of Rabbits: Physicochemical Properties That Regulate Penetration of Quinolone Antimicrobials

Pharmacokinetics of Sparfloxacin in the Serum and Vitreous Humor of Rabbits: Physicochemical Properties That Regulate Penetration of Quinolone Antimicrobials

Ocular Pharmacokinetics

Topical urea as a treatment for non‐infectious keratopathy

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